Roles in health: A 2016 review of studies since 1990 identified gaps in knowledge and uncertainties that complicate the assessment of copper status, disease prevention and requirements. Small amounts of copper are stored in the body, requiring daily intake to maintain the delicate copper balance.

Copper’s role in the development of Alzheimer’s disease remains unclear, including whether supplementation or restriction may delay its progression. Conflicting results were observed in a recent review: Some studies showed elevated levels of copper lowered disease risk, while others showed elevated levels promoted disease risk. Other studies suggest excessive amounts of copper and iron from supplements may contribute to impaired cognition, but research is limited.

One study suggests copper deficiency may be a contributing factor in the development of ischemic heart disease. Studies have shown copper deficiency can elevate blood lipid levels and blood pressure and could lead to cardiac abnormalities. However, despite the elevation in cardiac markers, studies indicate that supplementation doesn’t change cardiovascular disease risk factors.

Sources of copper: Widely available in plant and animal sources, copper content varies based on soil composition. Copper also can leach into tap water through copper pipes if corroded. The Environmental Protection Agency set the safe maximum level of copper in public water systems at 1.3 milligrams per liter.

Typical American diets are rich in copper, providing roughly 1,400 micrograms daily for men and 1,100 micrograms per day for women 19 and older. Less than 1 percent of adults are below the estimated average requirement for copper.

Bioavailability appears to be protective; absorption ranges from 75 percent when the diet contains 400 micrograms per day to only 12 percent when it contains 7.5 milligrams per day.

Copper also is available in supplements containing only copper, copper plus other ingredients and in multivitamins.

Signs of deficiency: Copper deficiency is generally rare, but possible reasons for inadequate intake or deficiency include genetic disorders such as Menkes disease in which copper absorption is faulty, malnutrition, prolonged parenteral nutrition, malabsorption and gastric bypass. High doses of supplemental zinc (50 milligrams or more daily) for prolonged periods of time can alter copper metabolism and result in deficiency. People with celiac disease may be at risk of deficiency, which is correctable with copper supplementation and a gluten-free diet.

Deficiency may lead to anemia, osteoporosis, connective tissue disorders, abnormal lipid metabolism, cardiovascular disease and greater risk of infection.

Toxicity: Copper toxicity is rare from dietary sources, except with Wilson’s disease, a rare genetic condition in which excessive amounts of copper accumulate in the body and can be fatal.

Excess supplementation or exposure to copper pots and pipes can increase intake beyond the Tolerable Upper Intake Level. Chronic elevated levels of copper can result in liver damage. Symptoms of copper toxicity are nausea, vomiting, diarrhea and stomach pain. Toxicity can lead to more serious conditions including liver damage, kidney failure, coma and death.

Bottom line: Most Americans consume adequate copper from food sources. Those considering copper supplementation should consult a health care provider. To better understand the role of copper in health, large-scale studies evaluating the relationship of copper and health with reliable biomarkers are needed.

References

Baheri S, et al. Role of Copper in the Onset of Alzheimer’s Disease Compared to Other Metals. Front Aging Neurosci. 2018:9:article 446.
Bailey RL, Fulgoni VL 3rd, Keast DR, Dwyer JT. Dietary supplement use is associated with higher intakes of minerals from food sources. Am J Clin Nutr. 94 (5) (2011) 1376–1381.
Barnard ND, Bush AI, Ceccarelli A, Cooper J, de Jager CA, Erickson KI, et al. Dietary and lifestyle guidelines for the prevention of Alzheimer’s disease. Neurobiol Aging. 2014;35 (Suppl 2):S74-8.
Bost M., et al. Dietary copper and human health: Current evidence and unresolved issues. J Trace Elem Med Bio. 2016;35: 107–115.
Brewer CJ. Copper toxicity in Alzheimer’s disease: cognitive loss from ingestion of inorganic copper. J Trace Elem Med Bio. 26 (2–3) (2012) 89–92.
Copper. In: Dietary reference intakes for vitamin A, vitamin K, boron, chromium, copper, iodine, iron, manganese, molybdenum, nickel, silicon, vanadium, and zinc. Institute of Medicine (US) Panel on Micronutrients. 2001:224-257.
Copper [Fact sheet]. National Institutes of Health website. https://ods.od.nih.gov/factsheets/Copper-HealthProfessional/. Accessed July 9, 2019.
Copper. Oregon State University Linus Pauling Institute, Micronutrient Information Center website. https://lpi.oregonstate.edu/mic/minerals/copper. Published January 2014. Accessed October 24, 2019.
DiNicolantonio JJ, Mangan D, O’Keefe JH. Copper deficiency may be a leading cause of ischaemic heart disease. Open Heart. 2018;5(2):e000784. Published Oct 8, 2018.
DiSilvestro RA, et al. A randomized trial of copper supplementation effects on blood copper enzyme activities and parameters related to cardiovascular health. Metabolism. 2012;61(9); 1242–1246.
Electronic Code of Federal Regulations, Title 40, Part 141. Environmental Protection Agency. Published 2007.
Keenan J, et al. Acute exposure to organic and inorganic sources of copper: Differential response in intestinal cell lines. Food Sci Nutr. 2018;6(8):2499–2514.
Krishnamoorthy L. et al. Copper regulates cyclic-AMP-dependent lipolysis. Nat Chem Biol. 2016;12: 586–592.
Position of the Academy of Nutrition and Dietetics: Micronutrient Supplementation. J Acad Nutr Diet. 2018: 118 (11): 2162-72.
Prohaska JR. Impact of copper deficiency in humans. Ann NY Acad Sci. 2014;1314:1-5.
Rubio-Tapia A, et al. American College of Gastroenterology clinical guidelines: diagnosis and management of celiac disease. Am J Gastroenterol. 2013;108:656-76.
What We Eat in America, 2013-2014.2017 U.S. Department of Agriculture, Agricultural Research Service website. https://data.nal.usda.gov/dataset/what-we-eat-america-wweia-database. Accessed October 24, 2019.
Yang H, et al. Copper-dependent amino oxidase 3 governs selection of metabolic fuels in adipocytes. PLoS Biol. 2018: 16(9): 1-27.

Folate is best known for its role in the prevention of neural tube defects, which are birth defects of the brain and spine, specifically anencephaly and spina bifida. Folate also is an essential nutrient for enzyme reactions in protein and vitamin metabolism, as well as DNA and RNA synthesis.

Roles in health
In addition to reducing the risk of NTDs, folate is crucial in decreasing the risk of pregnancy complications including anemia, preterm birth, congenital heart defects and oral clefts.

Although folate is vital early in pregnancy during rapid cell division, growth and development, approximately 35 percent of non-pregnant women do not meet dietary intake recommendations of folate without the use of dietary supplements.

Trials show roughly 90 percent of NTDs and 40 percent of congenital heart anomalies are preventable when women of childbearing age supplement with 400 to 800 micrograms of folic acid for four weeks pre-conception and eight weeks post-conception. Timing is critical, as neural tube defects occur in the first few weeks of pregnancy.

In 1998, the U.S. Food and Drug Administration mandated folic acid fortification of enriched grain products to reduce NTDs. In 2016, the FDA approved the voluntary inclusion of corn masa flour to help Latinas who have a higher prevalence of NTDs. Folic acid fortification of grains has prevented NTDs in approximately 1,300 babies each year, and NTDs in the U.S. have declined by 35 percent since 1998.

Folate, along with vitamins B6 and B12, has been studied for its protective role in age-related cognitive decline with mixed results. Inadequate folate consumption may increase dementia.

There also may be an association between low blood folate levels and depression and response to antidepressant medication, but more research is needed to understand the relationship.

Folic acid supplementation can impact levels of homocysteine, an amino acid in the blood that, when high, is a risk factor for heart disease. However, folic acid’s role in reducing the risk of cardiovascular disease is unproven.

Current recommendations
Many organizations including the U.S. Preventive Services Task Force recommend women consume a supplement with a minimum of 400 to 800 micrograms of folic acid if they are capable of becoming pregnant. In 2017, after a thorough review of the literature, the USPSTF confirmed this recommendation. Women with a history of NTDs are advised to supplement with 4,000 micrograms of folic acid, in addition to folate from a varied diet.

The recommended dietary allowance is in dietary folate equivalents, or DFE, because folic acid in supplements and fortified foods is more easily absorbed (1 microgram DFE equates to 1 microgram folate and 0.5 to 0.6 microgram folic acid). Bioavailability of supplemental folic acid is 100 percent when consumed on an empty stomach and 85 percent when consumed with food, while the bioavailability of folate from food sources is estimated to be about 50 percent.

Sources of folate and folic acid
Folate occurs naturally in a variety of foods, and many foods are fortified with folic acid. Folic acid is available in multivitamins, prenatal vitamins, singularly and in B-complex dietary supplements.

Signs of deficiency
Folate deficiency is rare in the United States, but can be caused by inadequate dietary intake, alcoholism, smoking and conditions that alter nutrient absorption. People with the MTHFR genetic polymorphism are unable to convert folate to the active form.

Signs of deficiency include sores in the mouth and changes in skin color, hair and fingernails. Inadequate intake of folate or vitamin B₁₂ can result in megaloblastic anemia with symptoms including fatigue, weakness and shortness of breath.

Toxicity
Toxicity could result by exceeding the UL with folic acid supplements. High doses of folic acid supplements could lead to un-metabolized folic acid and may mask pernicious anemia, in which the body cannot properly absorb vitamin B¹².

Potential drug interactions
Folic acid supplements may interfere with methotrexate, reduce blood levels of anti-epileptic and anti-seizure medications, and lower serum folate levels. Sulfasalazine, used for ulcerative colitis, and cholesterol-lowering agents may impair folate absorption and cause deficiency.

Bottom line
Diet alone may not provide adequate folate for women of reproductive age. Those women should eat a folate-rich diet and take folic acid supplements at least one month before conception and continuing throughout pregnancy.

References

Agnew-Blais, J. et al. Folate, Vitamin B6 and Vitamin B12 Intake and Mild Cognitive Impairment and Probable Dementia in the Women’s Health Initiative Memory Study. J Acad Nutr Diet. 2015 Feb; 115(2): 231–241.
Bailey R, Pac S, Fulgoni V. Estimation of Total Usual Dietary Intakes of Pregnant Women in the United States. Published June 21, 2019. Accessed August 27, 2019.
Czeizel AE, Dudas I, Vereczkey A, Banhidy F. Folate deficiency and folic acid supplementation: the prevention of neural-tube defects and congenital heart defects. Nutrients. 2013;5(11):4760-4775.
Final Recommendation Statement: Folic Acid for the Prevention of Neural Tube Defects: Preventative Medication. U.S. Preventive Services Task Force website. Published January 10, 2017. Accessed August 27, 2019.
Finer LB, Zolna MR. Unintended pregnancy in the United States: incidence and disparities, 2006. Contraception. 2011;84(5):478-485.
Folate – Fact Sheet for Health Professionals. National Institutes of Health Office of Dietary Supplements website. Updated July 19, 2019. Accessed August 27, 2019.
Greenberg JA, Bell SJ, Guan Y, Yu YH. Folic Acid supplementation and pregnancy: more than just neural tube defect prevention. Rev Obstet Gynecol. 2011;4(2):52–59.
Halsted CH, et al. Metabolic interactions of alcohol and folate. J Nutr. 2002;132(8 Suppl):2367S-2372S.
Institute of Medicine, Food and Nutrition Board, authors. Dietary Reference Intakes: Thiamin, Riboflavin, Niacin, Vitamin B6, Folate, Vitamin B12, Pantothenic Acid, Biotin, and Choline. Washington, DC: National Academy Press; 1998.
Micronutrient Information Center: Folate Summary. Oregon State University Linus Pauling Institute website. Updated 2014. Accessed August 27, 2019.
Mitchell, Laura E. The US Preventive Services Task Force Statement on Folic Acid Supplementation in the Era of Mandatory Folic Acid Fortification editorial. JAMA. 2017;317(2):183-189.
Pfeiffer CM, et al. Dietary supplement use and smoking are important correlates of biomarkers of water-soluble vitamin status after adjusting for sociodemographic and lifestyle variables in a representative sample of US adults. J Nutr. 2013;143(6):957S-965S.
Pitkin RM. Folate and neural tube defects. Am J Clin Nutr. 2007;85:285S–288S.
Roberts, E., Carter, B., & Young, A. H. . Caveat emptor: Folate in unipolar depressive illness, a systematic review and meta-analysis. J Psychopharmacol. 2018;32(4), 377–384.
Rossi RE, Whyand T, Murray CD, et al. The role of dietary supplements in inflammatory bowel disease: a systematic review. Eur J Gastroenterol Hepatol. 2016;28:1357-64.
Shiliang Liu, K.S. et al Joseph, Effect of Folic Acid Food Fortification in Canada on Congenital Heart Disease Subtypes Clinical Perspective. Circulation, 2016; 134 (9): 647.
Tinker SC, et al. Folic acid intake among U.S. women aged 15-44 years, National Health and Nutrition Examination Survey, 2003-2006. Am J Prev Med. 2010;38(5):534-542.
Williams J, et al; Centers for Disease Control and Prevention. Updated estimates of neural tube defects prevented by mandatory folic acid fortification—United States, 1995-2011. Morb Mortal Wkly Rep. 2015;64(1):1-5.

Approximately half of all cases of anemia are due to iron deficiency, which can be fatal. The World Health Organization considers iron-deficiency anemia to be the world’s most common nutritional deficiency, affecting more than 50 percent of preschool aged children and pregnant women in developing nations and 30 percent to 40 percent in industrialized nations. Iron fortification of wheat flour, now mandated in 83 countries, has proven to be a practical approach to increasing iron intake.

Sources of iron
Dietary iron is found in two forms: heme from meat and other animal sources and non-heme from plant and iron-fortified foods.

Heme iron is less affected by other dietary factors and is highly bioavailable (15 percent to 35 percent absorption) compared to non-heme iron, which is less bioavailable (1 percent to 23 percent absorption) and affected by other foods. In general, people who eat a variety of foods, including meat and seafood, absorb 14 percent to 18 percent of the iron they consume, while those who eat a vegetarian diet absorb 5 percent to 12 percent, however, this can vary with diet and iron status.

Many people consume more non-heme iron than heme iron. Eating a source of vitamin C or poultry, meat or fish with non-heme iron foods can enhance the bioavailability of iron. Some foods and beverages such as soy and tea may affect iron absorption, but these effects are generally modest for people who eat a varied diet.

The Daily Value, or DV, for iron is 18 milligrams for people age 4 and older. Foods with 20 percent or more of the DV are considered excellent sources, and those with 5 percent or less are considered low in iron.

Iron dietary supplements often are recommended for people at risk for deficiency, such as infants, young children, teenage girls, pregnant women and premenopausal women.

Full-term healthy infants generally receive enough iron from their mothers to last four to six months. At 4 months old, supplemental iron is recommended for infants who are breastfed until iron-containing complementary foods are introduced.

Iron supplements can reduce the absorption of certain medications, such as levodopa and levothyroxine. Proton pump inhibitors can reduce iron absorption. Always discuss iron supplementation with a health care provider.

Current recommendations
The Health and Medicine Division of the National Academies of Sciences, Engineering and Medicine (formerly the Institute of Medicine) sets Recommended Dietary Allowances, or RDAs, for iron (mg/day). (See chart below.)

The Tolerable Upper Intake Level is 40 milligrams per day from birth to 13 years and 45 milligrams per day for people 14 and older, including those who are pregnant or breast-feeding.

Deficiency
Iron deficiency occurs with inadequate consumption or absorption and excessive iron losses.

The most common measurement of iron status is hemoglobin via blood draw, but definitive diagnosis requires additional biomarkers. Hemoglobin concentrations below 13 grams per deciliter for men and 12 grams per deciliter for women indicate iron-deficiency anemia.

Infants, young children, adolescent girls, female athletes, pregnant and premenopausal women, and women with heavy menstrual periods have the greatest risk for iron deficiency.

Children and pregnant women are the most vulnerable, given their increased nutrient needs. During pregnancy, iron-deficiency anemia increases the risk of low birth weight infants and maternal and perinatal mortality.

Pregnant women should be tested for anemia at the first prenatal visit and again during the third trimester. Infants also should be screened; exact timing varies and should be determined by a pediatrician. Emerging evidence suggests iron deficiency during infancy and childhood may have long-lasting detrimental effects on cognitive and neurodevelopment.

Also at risk are people with cancer, chronic blood loss, gastrointestinal disorders, chronic disease such as chronic infections and auto-immune disease, heart failure and nutrient deficiencies as well as frequent blood donors.

Symptoms of iron-deficiency anemia may include fatigue, pale skin and fingernails, weakness, dizziness, headache or swollen tongue.

Toxicity
Healthy adults are at very low risk of overconsuming iron, except from dietary supplements. As little as 20 milligrams and more likely at 60 milligrams of iron per kilogram of body weight can cause symptoms of acute toxicity, including abdominal pain, nausea, vomiting and constipation, or even organ failure and possibly death.

People with the genetic disorder hemochromatosis are at increased risk of iron toxicity and require treatment to prevent iron overload.

Bottom line
Iron is an essential micronutrient that is tied to many bodily functions. Ideally, most people will meet their iron needs through diet; in high-risk populations, supplementation may be advised.

References

Abbaspour N, Hurrel R, Kelishadi R. Review on iron and its importance for human health. J Res Med Sci. 2014 Feb;19(2): 164-174.
About Us. The National Academies website. Accessed June 19, 2019.
Anaemia prevention and control. WHO website. Accessed June 19, 2019.
Anaemia. WHO website. Accessed June 19, 2019.
Baker, R. and Greer, F. Diagnosis and Prevention of Iron Deficiency and Iron-Deficiency Anemia in Infants and Young Children (0–3 Years of Age). Pediatrics. Nov 2010, 126 (5) 1040-1050.
Fleing RE, Ponka P. Iron Overload in human disease. N Engl J Med. 2012;366:348-59.
Focusing on anaemia: Towards an integrated approach for effective anaemia control. WHO website. Published 2004. Accessed June 19, 2019.
Guidelines for Perinatal Care, 8th ed. Washington DC: American Academy of Pediatrics, American College of Obstetricians and Gynecologists;2017.
Hurrell R, Egli I. Iron bioavailability and dietary reference values. Am J Clin Nutr. 2010;91:1461S-7S.
Institute of Medicine (US) Panel on Micronutrients. Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc: a Report of the Panel on Micronutrients, Washington, DC: National Academy Press;2001.
Iron. Natural Medicines Database website. Updated April 23, 2019. Accessed June 19, 2019.
Melina V, Craig W, Levin S. Position of the Academy of Nutrition and Dietetics: Vegetarian Diets. J Acad Nutr Diet. 2016;116:1970-1980.
Office of Dietary Supplements health professional factsheets: iron. ODS website. Updated December 7, 2018. Accessed June 19, 2019.
Peña-Rosas JP, Field MS, Burford BJ, De-Regil LM. Wheat flour fortification with iron for reducing anaemia and improving iron status in populations (Protocol). Cochrane Database of Systematic Reviews 2014, Issue 9. Art. No.: CD011302. DOI: 10.1002/14651858.CD011302.
Stevens GA, et al. Global, regional, and national trends in haemoglobin concentration and prevalence of total and severe anaemia in children and pregnant and non-pregnant women for 1995—2011: a systematic analysis of population-representative data. Lancet Glob Health. 2013;1:1;e16 – e25.
What We Eat in America 2009-2010, 2011-2012. U.S. Department of Agriculture, Agricultural Research Service. Accessed June 20, 2019.

Mercury exists in three forms: organic (e.g. methylmercury in fish), inorganic (e.g. batteries and disinfectants) and elemental (e.g. dental amalgam and thermometers). All types of mercury accumulate in the body over time.

Found naturally in the environment, soil and as a byproduct of pollution in the air, mercury is transformed by bacteria into the harmful organic compound methylmercury. In the United States, more than 3,000 lakes have been closed to fishing due to mercury contamination.

Seafood recommendations and safety
Fish and shellfish contain protein, omega-3 fatty acids and other essential nutrients. The 2015-2020 Dietary Guidelines for Americans recommend adults eat a variety of protein foods, including two servings of seafood per week. Unfortunately, consuming seafood is the most common way people in the U.S. are exposed to mercury.

While small amounts of mercury from seafood do not pose serious health concerns for most people, pregnant women and young children are more susceptible to potential neurological development issues. Pregnant and lactating women should eat eight to 12 ounces of low-mercury seafood per week, and children should be served smaller portions one to two times per week based on their age and calorie needs.

Nearly all fish and shellfish absorb and accumulate methylmercury. Larger, long living fish such as swordfish and bigeye tuna accumulate the highest levels and pose the greatest risk.

Mercury levels range from 0.003 parts per million in scallops to 1.123 parts per million in tilefish from the Gulf of Mexico. Methylmercury in fish is 95 to 100 percent absorbed in the intestines. Centers for Disease Control and Prevention data shows most people have blood mercury levels below 10 micrograms/liter; levels under 20 micrograms/liter are normal and not associated with negative health effects.

The U.S. Environmental Protection Agency, or EPA, recommends eating low-mercury fish and limiting higher-mercury fish. Limit locally caught fish to one serving per week, if there is no advisory.

The EPA and U.S. Food and Drug Administration categorize fish in three levels for women of childbearing age (16 to 49), especially those who are pregnant or breast-feeding, and children older than 6 months. Adults should eat two or three servings per week of “Best Choices” or one serving per week of “Good Choices.”

Mercury poisoning
Mercury poisoning takes months or years to develop with excess exposure. Skin exposure, inhalation or ingestion of mercury can have harmful effects on the nervous, digestive and immune systems, lungs, kidneys, brain, heart and eyes.

Toxicity depends on dose, exposure, frequency and health of the person. Symptoms vary by type of mercury and may include tremors, insomnia, memory loss, neuromuscular effects, headaches, and cognitive and motor dysfunction.

There are no consensus criteria for the diagnosis of mercury overload. Treatment includes removal of the source and, in some cases, chelation therapy, which binds toxins in the bloodstream.

Populations affected
Pregnant and breast-feeding women, infants and young children are most susceptible to the effects of mercury. Of greatest concern is how methylmercury crosses the blood-brain barrier and placenta. High levels of regular exposure can result in serious neurological effects to a fetus and may lead to mental retardation in children. There may be an association between elevated methylmercury and risk of cardiovascular disease in adults, but evidence is mixed.

Bottom line
Evidence shows the benefits of consuming low-mercury fish outweigh the risks of mercury overload. Young children and women who are of childbearing age, pregnant or breast-feeding should consume the recommended weekly servings of low-mercury fish and avoid eating high-mercury fish.

References

Alina M, Azrina A, Mohd Yunus AS, et al. Heavy metals (mercury, arsenic, cadmium, plumbum) in selected marine fish and shellfish along the Straits of Malacca. Int Food Res J. 2012;19(1):135–140.
Bernhoft R. Mercury Toxicity and Treatment: A Review of the Literature. J Environ Public Health. 2012;2012:1-10.
Budtz-Jørgensen E, Grandjean P, Weihe P. Separation of risks and benefits of seafood intake. Environ Health Perspect. 2007;115(3):323-327.
Choi AL, Cordier S, Weihe P, Grandjean P. Negative confounding in the evaluation of toxicity: the case of methylmercury in fish and seafood. Crit Rev Toxicol. 2008;38(10):877-893.
Davidson PW, Strain JJ, Myers GJ, et al. Neurodevelopmental effects of maternal nutritional status and exposure to methylmercury from eating fish during pregnancy. Neurotoxicology. 2008;29(5):767-775.
Eating Fish: What Pregnant Women and Parents Should Know. U.S. Food and Drug Administration website. Updated March 29, 2019. Accessed April 16, 2019.
EPA-FDA Fish Advice: Technical Information. U.S. Environmental Protection Agency website. Accessed April 16, 2019.
Health Effects of Exposures to Mercury. U.S. Environmental Protection Agency website. Accessed April 16, 2019.
How People are Exposed to Mercury. U.S. Environmental Protection Agency website. Accessed April 16, 2019.
Jaishankar M, Tseten T, Anbalagan N, Mathew BB, Beeregowda KN. Toxicity, mechanism and health effects of some heavy metals. Interdiscip Toxicol. 2014;7(2):60-72.
Karagas MR, Choi AL, Oken E, et al. Evidence on the human health effects of low-level methylmercury exposure. Environ Health Perspect. 2012;120(6):799-806.
Mercury and health. World Health Organization website. Published March 31, 2017. Accessed February 13, 2019.
Mercury Levels in Commercial Fish and Shellfish (1990-2012). U.S. Food and Drug Administration website. Updated October 25, 2017. Accessed April 16, 2019.
Mercury Poisoning Linked to Skin Products. U.S. Food and Drug Administration website. Updated March, 27, 2018. Accessed April 16, 2019.
Oken E, Wright RO, Kleinman KP, et al. Maternal fish consumption, hair mercury, and infant cognition in a U.S. cohort. Environ Health Perspect. 2005;113(10):1376-1380.
Omega-3 Fish Oil and Pregnancy. American Pregnancy Association website. Updated September 2, 2016. Accessed April 16, 2019.
Procter SB, Campbell CG. Position of the Academy of Nutrition and Dietetics: Nutrition and lifestyle for a healthy pregnancy outcome. J Acad Nutr Diet. 2014;114(7):1099-1103.
Questions & Answers from the FDA/EPA Advice on What Pregnant Women and Parents Should Know about Eating Fish. U.S. Food and Drug Administration website. Updated March 27, 2019. Accessed April 16, 2019.
Sagiv SK, Thurston SW, Bellinger DC, Amarasiriwardena C, Korrick SA. Prenatal exposure to mercury and fish consumption during pregnancy and attention-deficit/hyperactivity disorder-related behavior in children. Arch Pediatr Adolesc Med. 2012; 166: 1123–1131.
Strain JJ, Davidson PW, Bonham MP, et al. Associations of maternal long-chain polyunsaturated fatty acids, methyl mercury, and infant development in the Seychelles Child Development Nutrition Study. Neurotoxicology. 2008;29(5):776-782.
U.S. Department of Health and Human Services and U.S. Department of Agriculture. 2015 – 2020 Dietary Guidelines for Americans. 8th Edition Published December 2015. Accessed April 16, 2019.
Virtanena J, Rissanen TH, Voutilainen S, Tuomainen TP. Mercury as a risk factor for cardiovascular diseases. J Nutr Biochem. 2007;18(2):75-85.
Ye BJ, Kim BG, Jeon MJ, et al. Evaluation of mercury exposure level, clinical diagnosis and treatment for mercury intoxication. Ann Occup Environ Med. 2016;28:5. 2016.

The American Dental Association recommends water fluoridation as a safe, effective means of protecting against cavities and reducing tooth decay by 20 percent to 40 percent. Despite numerous studies showing safety and efficacy, water fluoridation sparks a heated debate.

Roles in health
Fluoride protects teeth by strengthening the enamel, making it more resistant to acid and demineralization and thereby preventing cavities. Fluoride also helps remineralize enamel, reverse early signs of tooth decay and can prevent growth of harmful oral bacteria.

A 2015 Cochrane review questioned the impact of fluoride on cavities in adults, yet two government reviews concluded water fluoridation is effective in decreasing the prevalence and severity of cavities among adults and children. The CDC estimates fluoridated water reduces tooth decay by 25 percent among children and adults.

Current recommendations
Because insufficient data was available to set a Recommended Dietary Allowance, an Adequate Intake of fluoride was established in 1997.

In 2015, the U.S. Department of Health and Human Services revised the optimal fluoride level to 0.7 ppm for dental health. Concerns about dental fluorosis, a condition in which excess fluoride causes white lines or specks on children’s teeth, spurred this change from the 1962 recommendation of 0.7 to 1.2 ppm. In areas with naturally higher fluoride levels, communities must ensure the maximum level is below 4 ppm, a level considered hazardous.

Signs of deficiency
The only known sign of fluoride deficiency is an increased risk of cavities.

Potential adverse effects
Dental fluorosis can occur in children 8 and younger while teeth are still forming under the gums. Most cases of fluorosis are mild, affecting the appearance but not health of teeth. The National Research Council estimates the prevalence of severe dental fluorosis at near zero when fluoride concentrations are under 2 ppm. The incidence of fluorosis has increased primarily due to reconstituted infant formula made with fluoridated water and children swallowing toothpaste.

Parents of infants exclusively fed prepared formulas are advised to use fluoride-free water to minimize the risk of mild fluorosis. Children younger than 6 should not use fluoridated mouthwash and should be discouraged from swallowing toothpaste.

Skeletal fluorosis, also rare in the United States, involves the bones and joints. Early signs include nausea and vomiting, joint pain and stiffness that can advance over time to affect bone structure and increase risk of fractures. Risk for skeletal fluorosis occurs when consumption is above 6 ppm.

A 2017 study suggested high levels of fluoride in utero could impact cognition and IQ, yet a 2015 study refutes that water fluoridation is neurotoxic and lowers IQ. The Evidence Analysis Library’s Fluoride Systematic Review rated the association as having “limited evidence.”

Numerous studies have reviewed the potential association between water fluoride levels and cancer; most have not found a strong link.

Sources of fluoride
Fluoride is found naturally in soil, water and food; it also is commonly added to toothpaste, mouthwash, dental gels, fillings, dental floss and water supplies. In the U.S., the largest source of fluoride is fluoridated water. Amounts vary between communities, bottled waters and well water. Fluoride in most foods is low, less than 0.5 ppm. Tea and foods that are fortified or mixed with water can have higher levels. Prescription supplements are available for children living in areas where water is not fluoridated.

Bottom line
Numerous studies support the safety of low-dose fluoridated water for dental health. If desired, fluoride consumption can be lowered by drinking bottled water, using a fluoride filter for tap water and choosing fluoride-free toothpaste. Anyone concerned about excess fluoride consumption should consult a dentist.

References

2018 Fluoridation Facts. ADA website. Accessed February 8, 2019.
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Levy SM, Broffitt B, Marshall TA, Eichenberger-Gilmore JM, Warren JJ. Associations between fluorosis of permanent incisors and fluoride intake from infant formula, other dietary sources and dentifrice during early childhood. J Am Dent Assoc. 2010;141(10):1190-1201.
Over 70 Years of Community Water Fluoridation. CDC website. Updated May 4, 2016. Accessed February 8, 2019.
Promoting Oral Health through Water Fluoridation. FDI World Dental Federation website. Updated September 2014. Accessed February 8, 2019.
USDA National Fluoride Database of Selected Beverages and Foods, Release 2. USDA website. Accessed February 8, 2019.
U.S. Public Health Service Recommendation for Fluoride Concentration in Drinking Water for the Prevention of Dental Caries. Public Health Rep. 2015;130(4):318-331.
Water Fluoridation and Cancer Risk. ACS website. Updated July 24, 2015. Accessed February 8, 2019.
Water Fluoridation. CDC website. Updated August 5, 2016. Accessed February 8, 2019.
Water Fluoridation. Healthy Children website. Updated April 20, 2012. Accessed February 8, 2019.

Most Americans consume adequate amounts of zinc. Only 8 percent of people age 2 and older fall short of the estimated average requirement.

Roles in health
Zinc activates lymphocytes, or T-cells, and is crucial in mounting an immune response to resist disease and promote wound healing. Protein and DNA synthesis, cell division, proper taste and smell also rely on zinc.

Zinc lozenges or syrup frequently are used to treat the common cold in adults. If taken within 48 hours of symptoms, zinc may help reduce the duration and severity of symptoms by up to 40 percent. According to a 2011 meta-analysis, daily elemental zinc dosage must be at least 75 milligrams to be effective. However, despite numerous trials, zinc supplementation remains questionable for treating colds. Further, zinc lozenges have been known to cause adverse effects such as a bad mouth taste and constipation, but there is no evidence of long-term harm.

Fertility and low sperm quality in men may be linked to lack of zinc. In one small study, a dietary supplement that included zinc, folate, beta carotene, and vitamins C and E was associated with improved semen quality in men, but it’s not clear if zinc was responsible for these results.

Research suggests zinc and antioxidant vitamins may prevent or slow age-related macular degeneration by preventing cellular retina damage.

Emerging research is evaluating the role of zinc in treating acne, ADHD, osteoporosis and helping to prevent pneumonia.

Current recommendations
Children up to 6 months old have an Adequate Intake of 2 milligrams for both sexes and a Tolerable Upper Intake Level, or UL, of 4 milligrams. For Recommended Dietary Allowances for ages 7 months
and older, see the chart below.

Signs of deficiency
Zinc deficiency can impair immune function, wound healing, normal growth and appetite. In a zinc- deficient state, excess oxidation may lead to increased DNA damage.

While most Americans’ zinc intake is adequate, deficiencies could be due to malabsorption, chronic disease, sickle cell disease and poor intake. Excess iron and gastrointestinal conditions can decrease zinc absorption in the body.

In children, zinc deficiency can result in growth retardation and increased risk of infection, diarrhea and respiratory disease. The World Health Organization recommends zinc to help reduce childhood deaths from diarrhea. Deficiency can be difficult to assess because there is not a definitive biomarker of zinc status.

Sources of zinc
In addition to multivitamins, mineral supplements and cold remedies, zinc is found in a variety of foods.

There is not enough evidence to conclude differences in absorption between forms of zinc supplements, including zinc acetate, zinc gluconate, zinc picolinate and zinc sulfate.

Toxicity
Most Americans do not exceed the UL for consumption of zinc with food alone. It is estimated that less than 4 percent of zinc supplement users exceed the UL. Excess zinc can result in toxicity with adverse effects including nausea, vomiting, loss of appetite, stomach cramps, headaches and diarrhea. Long-term overuse (more than 40 milligrams daily) can lead to copper deficiency, which manifests as weakness and numbness in the arms and legs. Persistent use of nasal sprays and gels containing zinc can result in loss of the sense of smell.

Populations at risk
Pregnant women and young children are the highest-risk groups for zinc deficiency. An estimated 17 percent of the global population and 82 percent of pregnant women worldwide have inadequate zinc intakes. Other groups at risk include people with alcoholism, gastrointestinal disorders or chronic renal disease.

Bioavailability of zinc in some plant- based foods may be lower due to phytates that inhibit absorption, requiring up to 50 percent additional zinc for strict vegetarians.

Older adults are likely to consume inadequate amounts of zinc as they contribute to immune dysfunction and chronic inflammation during aging.

It is common for people with diabetes to be moderately zinc-deficient, potentially due to zinc loss through excess urination.

People who are infected with HIV are particularly susceptible to low-serum levels of zinc.

Zinc supplements have the potential to interact with medications and inhibit absorption of both zinc and the medication. Consult a health professional before taking a zinc supplement, especially if you also are taking tetracycline antibiotics, penicillamine or thiazide diuretics.

Bottom line
Zinc is a powerful antioxidant that can help fight infections, repair the body and produce healthy, new cells, but probably not prevent the common cold. A healthy, balanced eating plan can provide an adequate amount of zinc. Vegetarians should be mindful of dietary sources, since some food preparation techniques and food pairings may affect zinc bioavailability or absorption. Older adults with limited intake may benefit from a multivitamin or mineral supplement containing zinc to boost their immune system but should consult a health care provider first.

References

Alexander TH, Davidson TM. Intranasal zinc and anosmia: the zinc-induced anosmia syndrome. Laryngoscope. 2006;116:217-20.
Bailey RL, West KP Jr., Black RE. The epidemiology of global micronutrient deficiencies. Ann Nutr Metab. 2015;66(suppl 2):22-33.
Baum MK, Lai S, Sales S, Page JB, Campa A. Randomized, controlled clinical trial of zinc supplementation to prevent immunological failure in HIV-infected adults. Clin Infect Dis. 2010;50(12):1653-1660.
Chaffee BW, King JC. Effect of zinc supplementation on pregnancy and infant outcomes: a systematic review. Paediatr Perinat Epidemiol. 2012;26(suppl 1):118-137.
Chong EW, Wong TY, Kreis AJ, Simpason JA, Guymer RH. Dietary antioxidants and primary prevention of age related macular degeneration: systematic review and meta-analysis. BMJ. 2007;335:755.
Dietary supplement fact sheet: zinc. National Institutes of Health Office of Dietary Supplements website. Accessed December 11, 2018.
Eskenazi B, Kidd SA, Marks AR, et al. Antioxidant intake is associated with semen quality in healthy men. Hum Reprod. 2005;20(4):1006-1012.
Evans JR, Lawrenson JG. Antioxidant vitamin and mineral supplements for slowing the progression of age-related macular degeneration. Cochrane Database Syst Rev. 2006;(2).
Fulgoni VL, Keast DR, Bailey RL, Dwyer J. Foods, fortificants, and supplements: Where do Americans get their nutrients? J Nutr. 2011;141(10):1847-1854.
Gogia S, Sachdev HS. Zinc supplementation for mental and motor development in children. Cochrane Database Syst Rev. 2012;12.
Hemilla H. Zinc lozenges may shorten the duration of colds: a systematic review. Open Respir Med J. 2011;5:51-58.
Institute of Medicine Food and Nutrition Board. Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium, and Zinc. Washington, DC: National Academies Press; 2001.
King JC. Zinc: an essential but elusive nutrient. Am J Clin Nutr. 2011;94(2):679S-684S.
Larson CP, Saha UR, Nazrul H. Impact Monitoring of the National Scale Up of Zinc Treatment for Childhood Diarrhea in Bangladesh: Repeat Ecologic Surveys. PLOS Medicine. 2009;6(11).
Lassi ZS, Moin A, Bhutta ZA. Zinc supplementation for the prevention of pneumonia in children aged 2 months to 59 months. Cochrane Database Syst Rev. 2016;12.
Lin PH, Sermersheim M, Li H, Lee PHU, Steinber SM, Ma J. Zinc in Wound Healing Modulation. Nutrients. 2017;10(1):16.
Maret W, Sandstead HH. Zinc requirements and the risks and benefits of zinc supplementation. J Trace Elem Med Biol<e/m>. 2006;20(1):3-18.
Marra MV, Bailey RL. Position of the Academy of Nutrition and Dietetics: Micronutrient Supplementation. J Acad Nutr Diet. 2018;118(11):2162-2173.
Melina V, Craig W, Levin S. Position of the Academy of Nutrition and Dietetics: Vegetarian Diets. J Acad Nutr Diet. 2016;116:1970-1980.
National Nutrient Database for Standard Reference Release, April 2018. United States Department of Agriculture/National Agricultural Library website. Accessed December 6, 2018.
Robbins WA, Xun L, FitzGerald LZ, et al. Walnuts improve semen quality in men consuming a Western-style diet: randomized control dietary intervention trial. Biol Reprod. 2012;87(4):101.
Science M, Johnstone J, Rothe DE, Guyatt G, Loeb M. Zinc for the treatment of the common cold: a systematic review and meta-analysis of randomized controlled trials. CMAJ. 2012;184(10):E551-561.
Singh M, Das RR. Zinc for the common cold. Cochrane Database Syst Rev. 2011;(2).
Spano M. Zinc and Inflammation — Age-Related Zinc Deficiency May Contribute to Chronic Disease Risk. Today’s Dietitian website. Published January 2013. Accessed December 11, 2018.
Wong CP, Ho E. Zinc and its role in age-related inflammation and immune dysfunction. Mol Nutr Food Res. 2012;56(1):77-87.
Zinc. Natural Medicines Comprehensive Database website. Updated October 23, 2018. Accessed December 13, 2018.

Roles in health
Selenium is involved in reproduction, metabolism, thyroid function, DNA production and protection from oxidative damage and infection. Studies have associated low levels with increased risk for cancer, cardiovascular disease, cognitive decline and thyroid disease. Low dietary consumption of selenium may be associated with obesity.

Selenium’s antioxidant properties and its effect on DNA repair and the endocrine system may play a role in the prevention of certain cancers. However, the relationship between selenium and cancer is debated worldwide. In 2003, a qualified health claim for reduction of certain cancers was approved by the U.S. Food and Drug Administration for dietary supplements containing selenium. A 2016 meta-analysis suggested high selenium exposure through dietary sources may have varying effects on cancer prevention.

A 2006 meta-analysis showed high selenium concentrations were associated with a reduction in coronary heart disease risk. Some experts recommend selenium supplements for patients with or at risk for coronary heart disease and for those undergoing cardiac surgery.

*All foods listed here are rated “excellent” sources.

Immune function may be boosted with increased selenium levels, which can help protect against infectious diseases caused by viruses such as HIV, influenza and hepatitis C.

Since aging is characterized by loss of muscle mass and selenium plays a key role in muscle function, reduced serum selenium levels may be associated with age-related decline in brain function.

Studies indicate supplementation may offer benefits only to those whose selenium consumption already is inadequate, and emerging research suggests genetic factors may affect how people respond to supplementation.

Current recommendations
The Institute of Medicine uses Adequate Intake, or AI, for infants due to insufficient evidence to develop a Recommended Dietary Allowance. The daily AI is 15 micrograms for infants 0 to 6 months and 20 micrograms for infants 7 to 12 months.

The RDA is 20 micrograms for children ages 1 to 3, 30 micrograms for ages 4 to 8, 40 micrograms for ages 9 to 13, and 55 micrograms for ages 14 and older. Pregnant and lactating women require 60 micrograms and 70 micrograms, respectively.

Daily Tolerable Upper Intake Levels are 45 micrograms for infants 0 to 6 months, 60 micrograms for infants 7 to 12 months, 90 micrograms for children 1 to 3 years, 150 micrograms for ages 4 to 8, 280 micrograms for ages 9 to 13, and 400 micrograms for ages 14 and older.

Sources of selenium
Selenium is found naturally in many foods. However, the amount depends on the selenium concentration of soil and water. Most Americans get enough selenium from their diet, primarily from grains, meat, poultry, fish and eggs.

Selenium is available as a supplement and in multivitamins in the highly absorbable form of selenomethionine.

Signs of deficiency
Rare in the United States and estimated to effect 1 billion people worldwide, selenium deficiency is measured by concentration in serum and plasma. Deficiency may increase the risk of thyroid disease and can cause Keshan disease (cardiomyopathy), Hashimoto’s thyroiditis, male infertility and possibly Kashin-Beck, a type of osteoarthritis.

Populations at risk
Diarrhea, malabsorption and poor intake by people with HIV can lead to deficiency. Kidney dialysis also increases deficiency risk. Selenium may interact with medications such as Cisplatin, a chemotherapy drug that can lower selenium levels.

Toxicity
Selenium toxicity is uncommon in the United States. Consuming excess selenium can cause symptoms such as garlic breath, nausea, diarrhea and skin rash. Hair and nail loss are common signs of chronic overconsumption. Dangerously high intakes can cause kidney failure, heart attack and heart failure.

Bottom line
Selenium is important in many aspects of health and may boost the immune system, slow mental decline and reduce risk of some diseases, but more research is needed to confirm this.

References

Benstoem C, Goetzenich A, Kraemer S et al. Selenium and its supplementation in cardiovascular disease—What do we know? Nutrients. 2015;7:3094–3118.
Cai X, Wang C, Yu W et al. Selenium Exposure and Cancer Risk: an Updated Meta-analysis and Meta-regression. Sci Rep. 2016; 6:19213.
Chun OK, Floegel A, Chung SJ, Chung CE, Song WO, Koo SI. Estimation of antioxidant intakes from diet and supplements in U.S. adults. J Nutr. 2010;140:317-24.
Institute of Medicine, Food and Nutrition Board. Dietary Reference Intakes: Vitamin C, Vitamin E, Selenium, and Carotenoids. National Academy Press, Washington, DC, 2000.
Jones G, Droz B, Greve P et al. Selenium deficiency risk predicted to increase under future climate change. Proc Natl Aca Sci. 2017;114(11):2848-2853.
Kalantari H, Das D. Physiological effects of resveratrol. BioFactors. 2010;36(5):401-406.
Meplan C. Selenium and chronic diseases: A nutritional genomics perspective. Nutrients. 2015;7:3621–3651.
National Institutes of Health. Dietary Supplement Fact Sheet: Selenium. Updated February 11, 2016. Accessed August 9, 2018.
Wu Q, Rayman MP, Lv H et al. Low Population Selenium Status Is Associated With Increased Prevalence of Thyroid Disease. J Clin Endo Metab. 2015; 100 (11): 4037–4047.
Rayman MP. Selenium and human health. Lancet. 2012;379:1256-68.
Rees K, Hartley L, Day C, Flowers N, Clarke A, Stranges S. Selenium supplementation for the primary prevention of cardiovascular disease. Cochrane Database Syst Rev. 2013;1.
Sieja K, Talerczyk M. Selenium as an element in the treatment of ovarian cancer in women receiving chemotherapy. Gynecol Oncol. 2004;93:320-7.
Steinbrenner H, Al-Quraishy S, Dkhil MA, Wunderlich F, Sies H. Dietary Selenium in Adjuvant Therapy of Viral and Bacterial Infections. Adv in Nut. 2015;6(1):73-82.
Stone CA, Kawai K, Kupka R, Fawzi WW. Role of selenium in HIV infection. Nutr Rev. 2010;68:671-81.
Summary of Qualified Health Claims Subject to Enforcement Discretion. U.S. Food & Drug Administration website. Accessed October 25, 2018.
Tonelli M, Wiebe N, Thompson S et al. Trace element supplementation in hemodialysis patients: a randomized controlled trial. BMC Nephrol. 2015;16(1).
Vinceti M, Dennert G, Crespi C et al. Selenium for preventing cancer. Cochrane Database of Systematic Reviews. 2014.
Wang Y, Gao X, Pedram P et al. Significant beneficial association of high dietary selenium intake with reduced body fat in the coding study. Nutrients. 2016;8:24.

Roles in Health

Chromium enables the body to maintain normal blood sugar levels by enhancing the action of insulin and moving glucose from the blood into cells, which leads to greater insulin sensitivity.

Although chromium has been associated with many health benefits, evidence is lacking. Some studies show improved glucose metabolism and lipid levels with chromium supplementation in people with diabetes. National Health and Nutrition Examination Study data from 1999 to 2010 showed a lower incidence of Type 2 diabetes in those taking a chromium supplement. Other studies show conflicting results or no benefit.

Supplemental chromium, primarily in the form of chromium picolinate, has been studied for its potential impact on weight loss and improved insulin resistance. Although some studies have shown a modest reduction in body weight, the results are not clinically significant and side effects can be unpleasant.

Some body builders use chromium supplements because of the relationship between chromium and insulin, which is an anabolic hormone. However, most research shows chromium supplementation does not improve body composition.

While some studies have shown chromium supplementation can decrease total and LDL cholesterol in certain populations, the role of chromium supplements in lipid metabolism is inconclusive.

Current Recommendations

Ideal amounts of chromium are not well-defined. In 2001, the Food and Nutrition Board of the Institute of Medicine defined an Adequate Intake, or AI, level using estimates of average dietary consumption in specific populations. Daily AI begins at 0.2 micrograms for the first six months of life and progresses to 15 micrograms for ages 4 to 8. At age 9, daily AI begins at 21 micrograms for females and progresses to 25 micrograms up to age 50; for males, the daily AI begins at 25 micrograms and advances to 35 micrograms up to age 50. Pregnant and lactating women have a daily AI of 29 to 30 micrograms and 44 to 45 micrograms respectively. At age 50, daily AI is 20 micrograms for females and 30 micrograms for males.

A Tolerable Upper Intake Level has not been established because few adverse effects are associated with excess intake.

Sources of Chromium

Small amounts of chromium are found naturally in foods. Most people consuming a balanced diet get enough chromium from food and absorption can be enhanced with foods rich in vitamin C and niacin.

*Must have at least 3.5mcg chromium per serving to be considered a good source.

Chromium picolinate can provide as much as 500 micrograms per dose. Chromium chloride, chromium nicotinate and high-chromium yeast are other supplement forms of trivalent chromium. Evidence for the use of chromium supplements is lacking and it is not clear which form is best.

Signs of Deficiency

Because there are no tools to accurately measure chromium status, identifying deficiencies is difficult. Theoretically, a deficiency could impair glucose tolerance and blood sugar control and may contribute to glucose intolerance or the development of Type 2 diabetes. People on long-term parenteral nutrition may have inadequate intake of chromium unless it is administered daily.

Toxicity

Toxicity of trivalent chromium is low because it is poorly absorbed and rapidly excreted in urine. Chromium supplements in large amounts can induce side effects such as stomach problems, watery stool, vertigo, headaches, hives, low blood sugar and kidney or liver damage.

Populations at Risk

Pregnant and lactating women, children and people with liver or kidney disease should not take chromium supplements without consulting a doctor. Chromium may impair absorption, enhance excretion or amplify the effect of thyroid medications, antacids, acid reflux drugs, corticosteroids, beta-blockers, insulin and some painkillers.

Bottom Line

After years of research, the nutritional role of chromium continues to be debated. Since deficiency is rare and studies are inconclusive regarding potential benefits of supplements, chromium intake via food is recommended.

Roles in Health

Seventy-five percent of total body iodine is stored in the thyroid gland, allowing it to make hormones necessary for physiologic processes including growth, reproductive function, brain development, healing, energy metabolism, central nervous system and healthy thyroid function.

Iodine supplements are used to treat conditions including fibrocystic breast disease and inflammatory skin conditions and are used as an emergency treatment for radiation exposure.

Current Recommendations

The current daily Adequate Intake is 110 micrograms for children 0 to 6 months and 130 micrograms for ages 7 to 12 months. The Recommended Dietary Allowance is 90 micrograms for children ages 1 to 8, 120 micrograms for ages 9 to 13 and 150 micrograms for ages 14 and older. Pregnant and lactating women require up to 220 micrograms and 290 micrograms, respectively.

Tolerable Upper Intake Levels are 200 micrograms per day for children 1 to 3 years, 300 micrograms per day for 4 to 8 years, 600 micrograms per day for 9 to 13 years, 900 micrograms per day for 14 to 18 years and 1,100 micrograms per day for adults.

Sources of Iodine

Iodine naturally is present in seawater and in varying amounts in soil. Iodized table salt and iodine-rich foods are reliable sources, but values can vary widely. Most salt used in processed foods is not iodized. Iodine is not listed on the Nutrition Facts Panel (unless the food has been fortified with it), nor in the USDA Nutrient Database.

Iodine also is available as a supplement and often is included in multivitamins.

Signs of Deficiency

The WHO estimates that more than 30 percent of the world’s population has inadequate iodine intake, as measured by urinary iodine below 100 micrograms per liter.

When a person is deficient in iodine, the results can range from a subtle loss of intelligence quotient to cretinism (the extreme condition of severe mental and physical retardation). Recent meta-analyses suggest iodine deficiency is a risk factor for thyroid cancer. Some researchers suggest deficiency also may be linked to prostate, breast, endometrial and ovarian cancers.

Iodine deficiency disorders include mental retardation, hypothyroidism, goiter (thyroid enlargement) and other growth and development abnormalities. Low levels of thyroid hormone can lead to infertility in women and autoimmune disease of the thyroid, thereby increasing risk of thyroid cancer.

The most serious effect of iodine deficiency occurs in utero with damage to the fetus. Low birth weight and decreased child survival also may result. Deficiency in the mother during pregnancy and in the child during the first two years of life can have negative cognitive consequences resulting in impaired speech development, learning, reading and potential behavior disorders.

Even mild iodine deficiency during pregnancy can have long-term adverse impacts on fetal neurocognition. During childhood, iodine deficiency has been linked to reduced intellectual and motor performance. Treatment and prevention includes iodine supplements and iodized salt.

Populations at Risk

Pregnant and lactating women and infants are most susceptible to iodine deficiency, yet many people are unaware of the importance of iodine during pregnancy and early life. This can be especially harmful as fetal development can be affected before signs of deficiency become apparent.

Cruciferous vegetables are high in goitrogens that can cause iodine deficiency, but people whose diets contain adequate iodine can safely enjoy these vegetables in normal amounts.

Anyone, especially women of child-bearing age, following a paleo-type diet could be at risk of iodine deficiency. Using iodized salt can help fill the micronutrient gap. People who eat a vegan diet may be at increased risk of iodine deficiency because they do not consume seafood or dairy. Iodized salt and sea vegetables are important sources of iodine for this population.

Toxicity

Iodine supplements likely are safe when taken by mouth or applied to skin in recommended amounts. Excess intake can cause symptoms similar to iodine deficiency.

Chronic excess iodine intake from iodine-rich foods such as kelp, supplements or water that is high in iodine can cause toxicity. Prolonged use of iodine supplements without medical supervision is potentially unsafe. Nausea, diarrhea, runny nose, headache and a metallic taste are common side effects of iodine toxicity.

Bottom Line

More research is needed on mild iodine deficiency and cognition. Further, attention is needed to help people understand and appreciate the importance of consuming adequate amounts of iodine. Salt iodization is an important strategy to ensure safe and effective levels of iodine consumption around the world, yet it must be balanced with efforts to control and reduce sodium intake.

Awareness of potassium’s role in health has been heightened by its repeated classification by the Dietary Guidelines for Americans as an under-consumed nutrient. Potassium was declared a “nutrient of public health concern” by the 2015 Dietary Guidelines Advisory Committee because research has associated poor health outcomes, including hypertension and cardiovascular diseases, with low intake. It is estimated that less than 3 percent of the U.S. population achieves potassium intake above the Adequate Intake, or AI. Thus, the new Nutrition Facts label will list potassium and the Daily Reference Value will reflect an increase from 3,500 milligrams to 4,700 milligrams for the percent Daily Value.

Roles in Health

Potassium can blunt the effects of dietary sodium and help lower high blood pressure. Reducing hypertension in turn reduces risk of associated diseases such as heart disease, stroke and kidney disease. Highlighting potassium’s health impact, the U.S. Food and Drug Administration authorized the following health claim based on the Food and Drug Administration Modernization Act of 1997: “Diets containing foods that are a good source of potassium and low in sodium may reduce the risk of high blood pressure and stroke.”

Research shows potassium also may play a role in decreasing bone loss and reducing risk of kidney stones.

Current Recommendations

The Dietary Reference Intakes for potassium are under review by a scientific expert panel because of potassium’s perceived impact on chronic disease. The current daily AI is 3,000 milligrams for children 1 to 3; 3,800 milligrams for ages 4 to 8; 4,500 milligrams for ages 9 to 13; 4,700 milligrams for ages 14 and older, including pregnant women; and 5,100 milligrams for lactating women.

These values are based on dietary consumption amounts that were shown to maintain lower blood pressure, reduce risk of kidney stones and possibly minimize bone loss. Excess physical activity, sweating and diarrhea can increase demands for potassium.

Sources of Potassium

Potatoes, beans and many fruits and vegetables contain potassium. While milk and bananas contain some potassium, neither is considered a good source, contrary to popular belief (see chart below for other food sources of potassium).

One of the most-studied evidence-based approaches to helping people consume more potassium is the Dietary Approaches to Stop Hypertension, or DASH diet. For the past eight years, U.S. News & World Report ranked DASH “best overall diet” because it contains low-fat or fat-free dairy, fruits, vegetables, whole grains, fish, poultry, beans, seeds, nuts and vegetable oils. DASH also includes foods that are rich in potassium, dietary fiber and nutrients associated with good health and lower blood pressure.

Signs of Deficiency

Although low levels of potassium, or hypokalemia, can have serious health consequences, low potassium intake alone rarely causes deficiency in the general, healthy population because kidneys can lower excretion. The most common cause of hypokalemia is excessive losses, including profuse sweating, diarrhea, vomiting and kidney disease. Some diuretics, laxatives, steroids and types of antibiotics also can result in hypokalemia.

Temporary decreases in serum potassium normally are corrected after eating or drinking electrolytes; however, severe deficiency can be serious. Signs may include extreme fatigue, muscle spasms, weakness, cramping and irregular heartbeat.

Populations at Risk

Individuals at risk for hypertension and stroke, including African-Americans, older adults and people with diabetes and kidney disease, may be at risk for potassium deficiency. People with inflammatory bowel disease may have low potassium levels due to increased losses through the intestines.

Bottom Line

Potassium is an important nutrient for heart health and the prevention and management of high blood pressure. In addition to recommending mindful sodium consumption, registered dietitian nutritionists should emphasize the importance of potassium for cardiovascular health.

Roles in Health

Magnesium is needed in biochemical reactions, including energy production, nutrient metabolism, fatty acid and protein synthesis, transmission of nerve and muscle impulses, glucose control, blood pressure regulation and transport of calcium and potassium ions. Higher levels of serum magnesium have been associated with reduced risk of cardiovascular disease. Evidence supports an inverse relationship between dietary intake of magnesium and risk of Type 2 diabetes. One large cohort study showed magnesium intake may aid in preventing pancreatic cancer.

Research continues for magnesium therapy in risk reduction and management of heart disease, hypertension, Type 2 diabetes, pregnancy complications, asthma and migraine headaches. However, the Academy of Nutrition and Dietetics and the American Diabetes Association do not recommend magnesium supplementation to manage diabetes.

Current Recommendations

Daily requirements begin at 80 milligrams for children age 1 to 3 and advance to 410 milligrams for adolescent males and 360 milligrams for adolescent females. Adult males require 400 to 420 milligrams, while the RDA for adult females is 310 to 320 milligrams. Pregnant and lactating women require up to 400 milligrams and 360 milligrams, respectively, depending on age. Without sufficient data to establish an RDA, infants younger than 1 have an Adequate Intake based on consumption from breast-feeding and solid foods, or about 30 milligrams per day for infants 0 to 6 months, and 75 milligrams per day for infants 7 to 12 months.

Tolerable Upper Intake Levels for supplements are 65 milligrams per day for children 1 to 3 years old, 110 milligrams per day for ages 4 to 8 and 350 milligrams per day for ages 9 and older.

Sources of Magnesium

Magnesium is widely available in plant and animal foods and often is included in fortified foods and enriched grains. Soil health can impact the amount of magnesium in foods. Tap and bottled waters are potential sources; levels range from 1 to more than 120 milligrams per liter.

Magnesium supplements come in a variety of forms with varying bioavailability. Research shows aspartate, citrate, lactate and chloride forms may be absorbed better than oxide and sulfates. If supplements are used, they should be taken with meals to avoid the risk of diarrhea.

Signs of Deficiency

Chronic low levels of magnesium can negatively affect body functions that may be associated with chronic diseases, such as hypertension, cardiovascular disease, Type 2 diabetes, osteoporosis, Alzheimer’s disease and conditions including attention deficit disorder and migraines. Magnesium deficiency is rare, primarily because it is abundant in food and the kidneys limit urinary excretion when dietary intake is low. However, chronic low intakes of magnesium or conditions such as alcoholism can promote magnesium deficiency, which has been associated with an increased risk of cardiovascular disease, Type 2 diabetes and osteoporosis. Preliminary signs of deficiency include loss of appetite, nausea, vomiting and fatigue, which can progress to more serious symptoms such as abnormal heart rhythm, seizures and coronary spasms.

Populations at Risk

Older adults and individuals with gastrointestinal diseases, Type 2 diabetes, renal disorders or alcoholism are more susceptible to magnesium deficiency, since they are likely to underconsume or experience reduced absorption or increased losses of magnesium. Large doses of magnesium supplements, magnesium-based antacids or laxatives can interfere with magnesium absorption (especially for people who have impaired kidney function) and can cause diarrhea, nausea and cramping. Cases of fatal hypermagnesemia have occurred with medications exceeding 5,000 milligrams per day of magnesium.

Bottom Line

Studies continue to discover magnesium’s benefits in health promotion and disease prevention, but more research is needed. Well-balanced eating plans provide adequate amounts of magnesium. If deficiency is confirmed, dietary supplements may be required under the care of a physician.

Fried foods traditionally have been limited in healthy dietary patterns. But when you use small amounts of healthy unsaturated oils and the technology of an air fryer, fried foods can be back on the menu.

I tested the Philips Viva Collection Airfryer, equipped with “TurboStar” rapid-air technology that functions similar to a convection oven. The fryer’s air speed is what allows foods to cook quickly and crisply with minimal fat.  The fryer is easy to use and comes with a basket and rack, which are both dishwasher safe for easy cleanup. However, the bottom of the fryer, where fat collects, requires cleaning by hand.

Additional accessories are available that can turn the fryer into an oven or a grill pan, and a free app provides a wealth of information including tips for use, shopping lists and recipes. I was struck by the large size of the product, weighing about 12.8 pounds and roughly the size of a coffee maker.

Testing the Fryer

I experimented with chicken wings, Southern-fried chicken tenders, bacon and vegetables, including fresh and frozen potatoes. No preheating was necessary — a simple spritz of oil on the rack and the food was all it took to get started with the fried foods. My best results were with the vegetables.

I quickly learned that the trick to achieving fried foods that are crunchy on the outside yet still tender on the inside is not overcrowding the basket. Philips claims the fryer can be used to prepare food for a family of four, but my best results came when I used amounts to feed one to two people. When the basket was overloaded, despite shaking and turning the food, it resulted in foods that either did not brown or were overcooked to achieved proper browning, and wet-battered foods tended to stick to the rack even when both the food and rack were sprayed with oil. An additional double-layer rack can be purchased to double the basket’s capacity.

Bottom Line

If counter or pantry storage space is not an issue, the Philips fryer is a fun investment. It’s a bonus that this product can multitask for those living without a full kitchen, such as college students. The sweet spot for me was enjoying guilt-free French fries. Although other vegetables were delicious, I’ve achieved similar results with minimal oil and oven-roasting at high temperatures.

Despite its importance, choline is seriously overlooked. Data from the National Health and Nutrition Examination Survey suggest only 8 percent of American adults meet the adequate intake for choline; in the 2010 Dietary Guidelines for Americans, it was identified as a shortfall nutrient; and the 2015-2020 Dietary Guidelines for Americans estimate most Americans consume less than the adequate intake level.

Roles in Health

Choline is essential throughout the life cycle and is critical for brain and spinal cord development. Beginning in utero and continuing throughout childhood, choline is crucial for brain development and cognitive learning. Some research shows choline can improve memory by slowing cognitive decline in older adults.

Beyond the brain, choline is part of acetylcholine, a neurotransmitter important in muscle control, memory, mood and nervous system functions. Choline also plays a role in the stabilization of DNA, transportation of fats and (with folate) possibly the prevention of neural tube defects.

Choline’s role as a neurotransmitter signaling muscle cell activity may enhance athletic performance, according to preliminary research.

Some research shows choline may be cardioprotective, yet other studies have found conflicting results. Further research is needed to investigate the link between choline and cardiovascular disease risk.

Current Recommendations

In 1998, the Food and Nutrition Board established adequate and tolerable upper intake levels for choline. Requirements begin at 125 milligrams per day in the first six months of life and advance to 550 milligrams per day for males 14 and older and 425 milligrams per day for females 19 and older. Pregnant and lactating women require 450 milligrams per day and 550 milligrams per day, respectively.

Food Sources

The U.S. Food and Drug Administration recently set the daily value for choline at 550 milligrams per day for adults and children 4 and older based on the updated Reference Daily Intake values. Foods containing 55 to 104.5 milligrams (10 to 19 percent of the DV) of choline per serving can be declared a good source and foods containing 110 milligrams or more of choline per serving (20 percent or more of the DV) are an excellent source.

Supplements are usually necessary for pregnant and lactating women. Choline supplements are available as a single nutrient, with B vitamins and in some multivitamin mineral products in amounts ranging from 10 to 250 milligrams.

Signs of Deficiency

While most Americans fall short of meeting choline requirements, deficiency is rare in healthy, non-pregnant people. A choline deficiency can cause muscle damage and nonalcoholic fatty liver disease from abnormal deposits of fat in the liver.

Toxicity

Exceeding the tolerable upper intake level of 3,500 milligrams per day of choline for adults has been associated with vomiting, increased sweating, low blood pressure and fishy body odor. Further, the FNB warns that individuals with liver or kidney disease, Parkinson’s disease, depression or inherited trimethylaminuria may be at increased risk for severe side effects when exceeding the tolerable upper intake level.

Populations at Risk

Choline’s role in brain and spinal cord development makes its consumption vital for pregnant and lactating women. However, many prenatal supplements contain little choline. In June 2017, the American Medical Association recommended that prenatal vitamins increase the amount of choline from 0 to 55 milligrams to the adequate intake of 450 milligrams daily.

Individuals with genetic alterations also may be at higher risk of deficiency.

Bottom Line

The mounting evidence of choline’s importance makes it essential that registered dietitian nutritionists remain up to date on this critical nutrient. Throughout the life cycle, RDNs can help clients meet choline requirements for good health. Food manufacturers also may take note and start fortifying choline in foods to help consumers meet requirements more easily.

Emulsifiers made from plant, animal and synthetic sources commonly are added to processed foods such as mayonnaise, ice cream and baked goods to create a smooth texture, prevent separation and extend shelf life. However, in this era of “clean labels,” consumers question the necessity of additives in food.

Definition

A food emulsifier, also called an emulgent, is a surface-active agent that acts as a border between two immiscible liquids such as oil and water, allowing them to be blended into stable emulsions. Emulsifiers also reduce stickiness, control crystallization and prevent separation.

Functions, Names and Labeling

Emulsifiers create two types of emulsions: either droplets of oil dispersed in water or droplets of water dispersed in oil. Within the emulsion, there is a continuous and dispersed phase. In an oil-in-water emulsion, the continuous phase is the water and the dispersed phase is the oil; conversely, in a water-in-oil emulsion, the oil is the continuous phase.

Emulsions also can be made by applying mechanical force from a blender or homogenizer, which breaks down the dispersed phase into tiny droplets that become suspended in the continuous phase.

Low-fat spreads, ice cream, margarine, salad dressings and many other creamy sauces are kept in stable emulsions with the addition of emulsifiers. These additives also are widely used in other foods such as peanut butter and chocolate.

“Emulsifiers enhance the structure of baked goods by increasing whip-ability of batters, conditioning of dough and helping foods like pasta be more resistant to overcooking,” says food scientist Kantha Shelke, PhD, CFS.

Commonly used emulsifiers in modern food production include mustard, soy and egg lecithin, mono- and diglycerides, polysorbates, carrageenan, guar gum and canola oil.

Lecithin in egg yolks is one of the most powerful and oldest forms of an animal-derived emulsifier used to stabilize oil in water emulsions, for example, in mayonnaise and hollandaise sauce.

Emulsifiers are required by law to be included on a food’s ingredient list.

Oversight

Safety of emulsifiers is carefully regulated and tested by the U.S. Food and Drug Administration. Emulsifiers can be found on the Generally Recognized As Safe, or GRAS, list and are allowed in specific types of food and beverages at precise levels.

However, “FDA processes do not take into consideration individual diets of people who rely heavily on packaged foods,” Shelke says.

Although GRAS substances technically must meet the same safety standards as approved food additives, the GRAS process has evolved into a voluntary notification program and many GRAS additives have not been tested.

Congress defines safe as “reasonable certainty that no harm will result from use” of an additive. Additives are never given permanent approval. The FDA continually reviews the safety of approved additives, based on the best scientific knowledge, to determine if approvals should be modified or withdrawn.

Earlier in 2017, the FDA reviewed and confirmed the safety of carrageenan, an emulsifier whose safety has been questioned.

Safety

Most concerns about food additives target synthetic ingredients that are added to foods.
Published peer-reviewed intervention studies involving emulsifiers are limited to animals. A 2015 mouse study published in Nature found that two common synthetic emulsifiers, carboxymethylcellulose (CMC) or polysorbate 80 (P80), triggered weight gain and low-grade symptoms of inflammation and metabolic syndrome after 12 weeks.

“We suspect some emulsifiers act like detergents, upsetting the friendly bacteria in the microbiota, which triggers low-grade inflammation and causes excess eating,” says co-author Andrew Gewirtz, PhD.

A follow-up study by Gewirtz, a professor of biomedical sciences at Georgia State University, and his colleagues, published in Cancer Research, suggested the changes in gut bacteria from emulsifiers could trigger bowel cancer. A small clinical trial currently is underway to evaluate the role of CMC in humans.

In response to questions about the safety of some emulsifiers, a team of FDA scientists conducted a review of seven emulsifiers commonly used in food, including CMC and P80, to determine whether these ingredients pose any risk to human health. Their findings, published in 2017, confirmed that emulsifiers remained safe at the estimated exposure levels.

Final Thoughts

Food additives, including emulsifiers, play an important role in our food supply. Consumers who are concerned about these ingredients are encouraged to read labels and consume more minimally processed foods.

Definition

Color additives, including food dyes and pigments, are substances derived from both synthetic and plant, animal or mineral sources that add color to food. The objective is to enhance natural colors, add color to otherwise colorless foods, compensate for natural color variations and help identify flavors (such as yellow for lemon).

Functions, Names and Labeling

Synthetic color additives were developed to maintain hue and depth of color regardless of pH, temperature or presence of other ingredients. Synthetic colors are classified as “certifiable colors,” as they require U.S. Food and Drug Administration testing and certification each time a new color batch is used. Certifiable color additives are man-made and derived primarily from petroleum.

The nine FDA-approved “certifiable colors” include:

FD&C (FDA approved for Food, Drugs & Cosmetics) Blue No. 1, Blue No. 2, Green No. 3, Red No. 3, Red No. 40, Yellow No. 5 and Yellow No. 6; Orange B (only for use in hot dog and sausage casings) and Citrus Red No. 2 (only for use to color orange peels).

Other color additives derived from sources such as fruits, vegetables, insects and minerals are “exempt” from batch testing and certification, but they still must adhere to safety standards and regulatory requirements. Examples include grape skin extract, saffron, and fruit and vegetable juices. Some people may call these color additives “natural.” However, the term “natural” is not regulated or defined by the FDA, and the FDA objects to the term’s use in products containing added color, whether from certifiable or plant- or mineral-derived colorants.

Certifiable colors must be declared on food labels by the name of the additive, with at least the color and number (such as “Blue 2”). Other color additives may be declared as “Artificial Color,” “Artificial Color Added” or “Color Added,” or by an equally informative term such as “Colored with Fruit Juice” or “Vegetable Juice Color.” Carmine and cochineal extract color additives must be declared on labels because some people are allergic to these substances.

The ability to replace synthetic with plant- or mineral-derived colorant compounds depends on and varies with the pH and temperature of the food or beverage. Certifiable colorants may be preferable when the color needs to be vibrant, stable for long periods of time or when a specific color cannot be achieved with plant- or mineral-derived options.

Oversight

The FDA oversees all color additives, which must be approved for use in food, dietary supplements, drugs and cosmetics, and includes ongoing review of scientific evidence on the safety of their use. In addition, the FDA sets specifications and limitations for types of foods to which each color additive may be added, maximum amounts allowed in foods and how they must be identified on labels.

Color additives are regulated a little differently than other additives. “Because of the potential to deceive consumers about quality or safety of food, color additives require proof of safety during the authorization procedure and cannot be registered as ‘generally recognized as safe,’ exempt from FDA approval,” says Kantha Shelke, PhD, CFS, principal at Corvus Blue, LLC, and adjunct faculty in food safety regulations at Johns Hopkins University.

Safety

Despite additional layers of oversight, some consumers are concerned about the safety of food dyes. The FDA asserts color additives are thoroughly evaluated prior to approval and safe when used in accordance with regulations. However, over the years, many colors — including yellows 1, 2, 3 and 4 — have been banned due to adverse health effects. Color additives that have been found to cause cancer in animals or humans may not be used in FDA-regulated products marketed in the U.S.

Scientists have examined the relationship between food coloring and hyperactive behavior in children with mixed results.

“The FDA has reviewed and will continue to examine the effects of food dyes on children’s behavior,” says Andrew Zajac, PhD, director of the Division of Petition Review in FDA’s Office of Food Additive Safety. “The totality of scientific evidence indicates that most children have no adverse effects when consuming color additives, but some evidence suggests that certain children may be sensitive to them.”

Adverse reactions to color additives are estimated to be quite rare overall, even among people with allergies. Research is limited in this area, and there is no scientific evidence to support a link between exposure to artificial coloring and allergies.

That said, some experts think color additives are completely unnecessary. “It’s better to color food with colorants from food sources or add no color at all than to use synthetic color additives without the benefit of long-term safety studies,” says Virginia Tech food science professor Sean F. O’Keefe, PhD.

Whether in response to mounting evidence or ongoing consumer concern, many companies around the world have begun eliminating food dyes from some or all of their products. The British government now requires warning labels on most foods containing color additives, which has led to the reformulation of many products.

Final Thoughts

There is a growing trend to replace synthetic colors with plant- or mineral-derived compounds. These are assumed to be safer, but without regulation of the term “natural” and without being batch tested or certified, plant- and mineral-derived color additives are not a panacea.

“It is essential that all colorants be tested with the same rigor, something not always done with ingredients such as fruit extracts that bestow a false sense of safety because they are derived from familiar plants and foods,” Shelke says.

Color additives, which confer no health or nutritional benefit, are unlikely to be dangerous for most people. For those wishing to avoid color additives, helpful strategies include reading food labels and eating more foods that are minimally processed.

Definition

Anticaking agents stop powders and granulated ingredients from clumping, and humectants stabilize foods through moisture control. Both food additives can be derived from natural sources or manufactured from chemical or artificial ingredients. They also are used in nonfood applications, such as cosmetics, detergents, pharmaceuticals and tobacco.

It is important to note that many food additives serve more than one role. Mannitol, for example, is an additive that functions as a humectant, nutritive sweetener and texturizer.

Functions, Names and Labeling

Anticaking agents function by absorbing excess moisture or by coating particles to make them more water repellant, which helps inhibit clumping. Added in very small amounts, these compounds prevent dry foods from sticking together, ensuring a product remains dry and free-flowing.

Humectants control water activity in foods, thus enhancing stability and viscosity, maintaining texture and reducing microbial activity. If processed foods were consumed within a few days, food additives would not be necessary; since many food products sit on shelves in stores and homes for some time, additives aid in reducing water activity while keeping foods moist and safe for a longer shelf life.

Humectants

Foods that need to be kept moist risk potential bacterial growth. Moisture in food affects microbial activity, physical and sensory properties and possible chemical changes. Moisture in food can be controlled by removing it through dehydration or chemically binding it with humectants. Humectants control moisture changes caused by humidity fluctuations in processing, transit and storage on the shelf.

Dry cereal with raisins, candy with liquid centers, cheese, coconut, marshmallows and baked goods are a few examples of foods that rely on humectants. Humectants also are used in military and space technology to allow foods such as meat to be stored without refrigeration for longer periods of time.

Sugar and salt are the oldest and most widely used humectants. Examples of other commonly used humectants include glycerin, honey, sugar alcohols, glucose syrup, egg yolk, egg white, molasses and alpha hydroxy acids such as lactic acid.

Anticaking Agents

Fine-particle solids such as dry milk powder, flour, baking powder, cake mixes and powdered sugar are a few foods that benefit from anticaking agents, which prevent the formation of lumps and keep the products flowing freely. Without them, coffee powders in vending machines would not function properly and foods like grated cheese could form clumps and become sticky.

Most anticaking agents are made from synthetic substances such as silicon dioxide, magnesium carbonate and iron ammonium citrate. Calcium silicate, commonly added to table salt, absorbs both oil and water. Natural anticaking agents include magnesium silicate and corn starch.

Oversight

Humectants and anticaking agents are direct food additives that must be approved before use by the U.S. Food and Drug Administration. Assessment of a food substance includes an evaluation of its safety and functionality, including all studies on its stability, purity, potency, performance and usefulness.

Additive standards are defined with strict criteria, including safety, lack of adverse odors and flavors, and documented need of use before approval is granted. Maximum usage levels vary depending on the additive and food in which it is used. For example, silicon dioxide used in shredded cheese and powdered mixes has a limit of 2 percent by weight of the food.

Recently, a few government rulings have changed the status of anticaking agents and humectants. The new ruling removes partially hydrogenated oils, used as an anticaking agent, from the “Generally Recognized as Safe” list and gives manufacturers until the summer of 2018 to remove it from their products.

Safety

People sensitive to humectants, especially when ingested in large amounts, may suffer from nausea or diarrhea. Sugar alcohols in large doses may have a laxative effect.

Humectants and anticaking agents continue to be active areas of research and development in an effort to discover safe, natural alternatives and emerging technologies that can offer additional benefits to our food supply and the planet.

Final Thought

Humectants and anticaking agents are used in very small amounts to safeguard the food supply and maintain quality during shelf life. Extensive research and testing have deemed these additives safe in approved amounts. However, anyone with questions about food additives can consult a registered dietitian nutritionist.

Definition

Extracted primarily from natural substances, stabilizers, thickeners and gelling agents are approved direct additives incorporated into foods to provide structure, viscosity, stability and other qualities, such as maintaining existing color.

Functions, Names and Labeling

Thickeners, stabilizers and gelling agents are classified separately but overlap in functionality. When dissolved or added to foods, they create stiffness, stabilize emulsions or form gels.

Thickeners range from flavorless powders to gums and are chosen for their ability to work in a variety of chemical and physical conditions. Variables affecting choice of thickener include pH, frozen state, clarity and taste. Starches, pectin and gums are the most common commercial thickeners used in soups, sauces and puddings.

Stabilizers are substances that increase stability and thickness by helping foods remain in an emulsion and retain physical characteristics. Ingredients that normally do not mix, such as oil and water, need stabilizers. Many low-fat foods are dependent on stabilizers. Lecithin, agar-agar, carrageenan and pectin are common in ice cream, margarine, dairy products, salad dressings and mayonnaise.

Gelling agents also function as stabilizers and thickeners to provide thickening without stiffness through the formation of gel in jellies, jams, desserts, yogurts and candies. Gums, starches, pectin, agar-agar and gelatin are common gelling agents.

Home cooking achieves the same structural changes with the addition of familiar starches, grains, egg yolks, yogurt, gelatin, mustard and vegetable purees.

Thickening agents also are used in treating medical conditions, such as dysphagia, to make swallowing easier and reduce the risk of aspiration.

To help consumers understand the function of the food additive, a classification is indicated on food labels — for example, “pectin (gelling agent).” Most direct additives are identified on the ingredient label of foods.

Thickeners, stabilizers and gelling agents are largely polysaccharides or derived from protein sources, for example:

Polysaccharides

• Starches: arrowroot, cornstarch, potato starch, sago, tapioca
• Vegetable gums: guar gum (extracted from guar bean), xanthan gum (from microbial fermentation used in gluten-free baked goods), locust bean gum (from carob tree)
• Pectin (from apples or citrus fruit)

Protein

• Collagen, egg whites, gelatin (from animal collagen), whey

Others

• Sugars: agar (from algae), carrageenan (from seaweeds and used to prevent separation in dairy products and ice cream)
• Sodium pyrophosphate (used in common foods such as canned fish and instant pudding)
• Lecithin (found in egg yolk, legumes and corn)
• Mono- and diglycerides (stabilizers naturally present in many seed oils)

Sources are primarily natural (arrowroot, gelatin, starches) but also can be synthetic (carboxymethyl cellulose, methyl cellulose).

Oversight

Thickeners, stabilizers and gelling agents must be authorized by the Food and Drug Administration before use. Standards for food additives are clearly defined with strict criteria, and there must be a documented need for their use before approval is granted. Maximum usage levels vary depending on the additive and the food in which it is used.

For example, stabilizers in frozen dairy desserts, fruit and water ices and in confections and frostings cannot exceed 0.5 percent by weight of the final product. Emulsifier, flavoring adjuvant, stabilizer or thickener in baked goods have the same 0.5 percent by weight limit.

Safety

Today, food additives are scrutinized, regulated and monitored more closely than at any other time. All new food additives undergo a rigorous testing and safety assessment to minimize potential adverse effects to human health. However, side effects and nutrient-drug interactions may result from large doses. For example, consuming more than 15 grams of xanthan gum may cause nausea, flatulence and bloating. Food-drug interactions are possible with certain medications; carrageenan may cause adverse side effects in people taking anticoagulants and antihypertensive drugs, and pectin may interact with antibiotics and cholesterol-lowering drugs.

Final Thought

Registered dietitian nutritionists can help consumers feel more comfortable about food additives by communicating their similar role in home kitchens.

“While the name of the ingredient may be unfamiliar, the mode of action in the food matrix is similar,” says Heather Dover, RDN, research assistant at the Center for Research on Ingredient Safety at Michigan State University.

“Most concerns about food additives are related to synthetic ingredients added to foods, yet 99 percent of these additives are derived from natural sources and meet all of the FDA standards for safety, intended use and populations,” says Roger Clemens, DrPH, and former president of the Institute of Food Technologists. “For over 100 years of usage, these direct additives have posed no adverse effect for any population.”

Definition

Food preservatives play a vital role in preventing deterioration of food, protecting against spoilage from mold, yeast, life-threatening botulism and other organisms that can cause food poisoning. By extension, preservatives reduce food cost, improve convenience, lengthen shelf life and reduce food waste.

Functions, Names and Labeling

There are two modes of preservation: physical and chemical. Physical preservation refers to processes such as refrigeration or drying. Chemical preservation is adding ingredients to a food for the purpose of preventing potential damage from oxidation, rancidity, microbial growth or other undesirable changes — and is considered a “direct additive.”

The U.S. Food and Drug Administration classifies both natural preservatives (for example, from lemon juice, salt and sugar) and artificial preservatives as “chemical preservatives.” While many common preservatives occur naturally, manufacturers often use synthetic versions of these chemicals. Artificial preservatives can be divided into three major groups:

Antimicrobial agents destroy bacteria or inhibit the growth of mold on foods:

• Benzoates – the salts of benzoic acid
• Sorbates – sorbic acid and its three mineral salts, potassium sorbate, calcium sorbate and sodium sorbate
• Propionates – the salts of propionic acid
• Nitrites – the salts of nitrous acid

Antioxidants inhibit oxidation:

• Sulfites – a group of compounds containing charged molecules of sulfur compounded with oxygen, including sodium sulfite, sodium bisulfite, sodium metabisulfite, potassium bisulfite and potassium metabisulfite
• Vitamin E (tocopherol) – a fat-soluble vitamin
• Vitamin C (ascorbic acid) – a water-soluble vitamin and its salts, sodium ascorbate, calcium ascorbate and potassium ascorbate
• Butylated hydroxyanisole (BHA) – a waxy solid used to preserve butter, lard, meats and other foods
• Butylated hydroxytoluene (BHT) – similar in structure and function to BHA, but in powder form

Chelating agents bind metal ions in certain foods to prevent oxidation:

• Disodium ethylenediaminetetraacetic acid (EDTA) – used in food processing to bind manganese, cobalt, iron or copper ions
• Polyphosphates – used as anti-browning agents in dips and washes for peeled fruits and vegetables
• Citric acid – found naturally in citrus fruits

All preservatives added to food products must be declared on the ingredient list on the food label using common names of ingredients. When no such name exists, synthetic forms can be listed. For example, synthetic vitamin B9 can be listed as “folic acid.” Preservative ingredients must either be identified as a preservative or the specific function must be given, such as “sorbic acid (to retain freshness).”

Oversight

The FDA has jurisdiction over all preservatives, with the Food Safety and Inspection Service sharing responsibility for the safety of food additives used in meat, poultry and egg products. The FDA mandates that preservatives not be used in such a way as to conceal damage or inferiority, make the food appear better than it is or adversely affect the nutritive value of the food. Food additives approved for use as preservatives are listed in the U.S. Code of Federal Regulations.

Safety

According to the regulatory authorities, preservatives are generally recognized as safe, or GRAS, in the quantities in which they are allowed in individual food products. “Safe” for food additives is defined to mean “a reasonable certainty in the minds of competent scientists that the substance is not harmful under the intended conditions of use.” Still, there are some preservatives of concern.

Sodium nitrite/nitrate used in processed meats is an example of compounds that may increase the potential of these foods to cause cancer. Studies have linked eating large amounts of processed meats with an increased risk of colorectal cancer. 

Sodium benzoate and sulfites appear to be safe for most people, but may cause adverse reactions in others. A 2007 study published in The Lancet suggests sodium benzoate and artificial food colorings may exacerbate hyperactivity in young children.

Although butylated hydroxyanisole, or BHA, is listed by the National Toxicology Program as “reasonably anticipated to be a human carcinogen,” the FDA considers it a GRAS substance in minute quantities. Meanwhile, butylated hydroxytoulene, or BHT, has been banned in some countries but has not been shown conclusively to be carcinogenic.

Final Thought

To be clear, a diet awash with processed foods may contain excessive preservatives — both artificial and natural (think salt and sugar) — and should be limited. But preservatives within the context of an overall healthful diet help safeguard food and protect consumer health, neither of which are reasonable tradeoffs.

“Removing preservatives compromises food safety, and there is no good scientific reason to avoid them,” says Robert Brackett, PhD, director of the Institute for Food Safety and Health. He used nitrates as an example: “The
risk of getting botulism from processed meats far outweighs the risk of the preservative especially when consumed in moderation.”

Nonetheless, emerging technological innovations aimed at replacing traditional preservatives are in the works. Development of technologies such as high-pressure processing and ultrasonic preprocessing with pulsed light are promising — and may yield additional benefits such as reduced water usage, energy efficiency and improved food quality.

Definition 

A food additive is a natural or synthetic (“artificial”) substance that is added to, or comes into contact with, a food during production or processing. There are direct additives — ingredients that help to preserve flavor, enhance nutrition, extend shelf-life or enhance taste, texture or appearance — and indirect additives — typically trace amounts of residues from packaging, storage or handling. 

Basic Functions 

Direct food additives may serve single or multiple functions, including preservatives used to prevent spoilage; emulsifiers and stabilizers that help keep blended ingredients from separating; anticaking agents that reduce the formation of lumps in granulated foods; humectants that help foods stay moist; thickeners that improve the texture of certain foods; and color additives used for visual appeal. Food additives also include vitamins and minerals added to replace those lost in processing (called “enrichment”) or that might not be present in the food but are lacking in most diets (called “fortification”). 

Chemical Names 

Scary-sounding names is a frequently mentioned factor in anti-additive conversations, often coupled with the suggestion that the longer the name, the less “safe” the ingredient — or that using chemical names serves to obscure transparency. In fact, chemical nomenclature is designed to prevent ambiguity. When an ingredient does not have a common name, such as “sugar,” a chemical name may be used — but that doesn’t mean the ingredient is less safe. 

Labeling 

As a rule, food labels should list the common names of ingredients. However, not all additives have succinct aliases — for example, whereas synthetic forms of vitamin B9 can be listed on a food label as “folic acid,” a synthetic vitamin B1 additive may appear as “thiamin mononitrate.” In addition, certain additives, namely preservatives, require their specific function to appear after their name, such as “sorbic acid (to retain freshness).” Furthermore, when an ingredient itself contains two or more sub-ingredients, the food label must reflect those sub-ingredients. On the other hand, some additive ingredients may be listed collectively without further specification (think “artificial flavors”) as long as they are used in quantities and purposes for which they are approved, helping manufacturers safeguard trade secrets.

Oversight

The Federal Food, Drug and Cosmetic Act, first passed in 1938, gives authority to the U.S. Food and Drug Administration to oversee food product ingredients and how they must be listed on food labels. As food technology evolved and new additives were developed, Congress passed an amendment requiring premarket approval of all new additives, or Food Additive Safety Determination. Exempt from this requirement are grandfathered substances that were already in use (called Prior Sanctioned Substances) and those that have been designated by experts in the scientific community as Generally Recognized As Safe (GRAS). Although technically GRAS substances must meet the same safety standards as approved food additives, over the decades, the GRAS process has evolved into a voluntary notification program. So if a company wants to use a new substance in its food, it can either submit it to the FDA for premarket approval as an additive or, with review from scientific experts, determine it is GRAS. The company may then move forward with using the substance in its products, and it may (but is not required to) notify the FDA of the new GRAS substance. As a result, although the FDA maintains a registry of more than 10,000 food additives — of which roughly half are direct additives and more than 600 are on the GRAS list — there is an indeterminate number (one study reported approximately 1,000) of GRAS substances about which the FDA may not have been notified. 

In 2010, a U.S. Government Accountability Office report concluded that greater oversight is needed to help ensure the safety of all new GRAS determinations, citing gaps in information about substances currently in the food supply, and address challenges to existing GRAS substances. A 2013 Pew Charitable Trusts report echoed these findings, adding criticism over conflicts of interest arising from conclusions developed by company employees and consultants, and legislative ambiguity surrounding the FDA’s actual ability to enforce compliance. The FDA responded through the issuance of a final rule in August 2016 designed to demonstrate more stringent GRAS standards — namely clarifying criteria for and documentation of all GRAS conclusions, strongly encouraging companies to work with the FDA when considering new substances.

Final Thought 

“Countless studies and hours of scientific evaluation go into the process of food substance safety review,” says Hilary Thesmar, PHD, RD, Food Marketing Institute Chief Food and Product Safety Officer. “However, practitioners with concerns about an additive should use the evidence-based analysis process to evaluate the literature in peer-reviewed journals and conduct their own risk analyses.”  

Many individuals who are unable to eat by mouth rely on commercial formulas and may not be aware of other options. But with proper guidance, gastrostomy-fed people (who have a tube inserted into their abdomen that connects to their stomach) can have the option of making their own formula using whole foods — called blenderized feedings.

Potential Benefits

Vegetables, fruits, grains and legumes are packed with fiber and phytonutrients that are ideal for gut health. Many people who use blended feedings see a substantial improvement in their gastrointestinal function. “When people switch from commercial formulas to blended feedings, we see less abdominal bloating, nausea, reflux and retching, improved stools, better GI tolerance and, in general, they feel better and have more energy,” says Atlanta pediatric gastroenterologist Stanley Cohen, MD.

In the past 10 years, Houston pediatric dietitian Kristi King, MPH, RDN, LD, CNSC, says she has observed marked improvement in her patients’ GI symptoms (and quality of life) when switching to whole-food feedings. “Blended whole foods are trending in hospitals, either by using the hospital’s own recipes or commercial whole-food formulas, because patients prefer it and usually tolerate it better than some other formulas,” says King.

At home, eating the same meals as the family and “enjoying a variety of foods, the aromas and even burps of familiar food gives tube-fed patients satisfaction and a feeling of normalcy,” says Alissa Rumsey, MS, RD, CDN, CSCS, a nutrition and wellness consultant in New York City. Most feedings are done just like meals, three to six times per day, and are administered through the gastrostomy tube using a syringe.

Another advantage of whole-food feeding is that ingredients can be customized to meet an individual’s nutritional needs. This is especially important for anyone with intolerances or allergies to ingredients in commercial formulas.

While a considerable time commitment is required to prepare the feedings, there also are economic savings over most commercial formulas, especially if they are not covered by health insurance.

Possible Limitations

Risk factors associated with preparing homemade formulas include nutritional adequacy, safe food handling, tube clogging and improper administration.

Meeting nutritional needs with blended whole foods takes meticulous planning and the oversight of an expert. “One of the greatest concerns is that home feedings won’t meet nutritional requirements,” King says. “Careful attention to food selection, safety and handling are essential because many tube-fed people have compromised immunity.”

Patients with jejunal tubes (which direct feedings into the small intestine without being digested in the stomach), fluid restrictions or on pumped overnight feedings are not good candidates for blended feedings. “Assess the caregivers and patients to make sure they have the time, knowledge and skills to manage the challenges of preparing safe and nutritionally adequate [homemade formula],” Cohen says.

DIY Formula 101

Making tube-feeding formula can be relatively easy with the right equipment. Almost any food can be liquefied with a commercial blender, and some companies offer medical and RDN discounts.

Certain foods, such as cheese, seeds, corn, nuts and stringy foods, are more difficult to blend. “Warm and cooked foods blend easiest,” Rumsey says. Choose nutrient-rich foods to prepare different flavors of formulas: fruit, vegetables, grains and yogurt, or meats, grains and oils. Another option is combining homemade and whole-food commercial formulas.

Add liquids to the mixture to achieve the necessary consistency to flow through the particular size of gastrostomy tube. And flush tubes with water before and after feedings to prevent clogging.

7 Formula Blending Tips for RDNs

An ideal candidate for blended feedings is a patient who is medically stable and has a family with the ability, motivation, time and commitment to appropriately prepare the feeding. These individuals should be able to follow instructions and food safety guidelines.

RDNs must monitor patients and provide support and supervision to ensure the right materials and resources are used. While blended whole-food feedings is an emerging practice with little research and few professional standards guiding preparation and use, these tips can help promote safe preparation:

• Wear gloves, wash hands often, use separate cutting boards and wash produce thoroughly.
• Keep formulas refrigerated and discard after 24 hours.
• Jars of pureed baby food are good options to add to the blender to help meet nutritional goals.
• Raw seafood, undercooked foods and unpasteurized juice or milk are not recommended.
• Feedings are ideally administered several times a day but also can be used with a pump if the feeding is completed within two hours.
• Use healthy fats and oils, such as avocados or vegetable oils, to add calories and essential fatty acids.
• Avoid highly processed foods, such as potato chips and cookies. Vary the fruits, vegetables, grains and protein foods to provide adequate nutrition.