Zinc is called an “essential trace element” because it's necessary for numerous chemical processes that take place within a cell. It is required for the activity of approximately 100 enzymes and it plays a role in immune function, protein synthesis, wound healing, DNA synthesis, and cell division. Zinc also supports normal growth and development during pregnancy, childhood, and adolescence and is required for proper sense of taste and smell. To maintain a steady state of zinc, daily intake is required because our bodies don’t have a specialized system for storing zinc.
There are six instances when people are at risk of zinc deficiency or inadequacy. Supplemental zinc may be appropriate in certain situations.
People with Gastrointestinal and Other Diseases
Digestive disorders such as ulcerative colitis, Crohn’s disease, and short bowel syndrome, can decrease zinc absorption. Other diseases associated with zinc deficiency include malabsorption syndrome, chronic liver disease, chronic renal disease, sickle cell disease, diabetes, malignancy, and other chronic illnesses. Chronic diarrhea also leads to excessive loss of zinc.
The bioavailability of zinc from vegetarian diets is lower than from non-vegetarian diets because vegetarians do not eat meat, which is high in bioavailable zinc and may enhance zinc absorption. In addition, vegetarians typically eat high levels of legumes and whole grains, which contain phytates that bind zinc and inhibit absorption.
Vegetarians sometimes require as much as 50% more of the RDA for zinc than non-vegetarians.
Pregnant and Lactating Women
Pregnant women, particularly those starting their pregnancy with borderline zinc status, are at increased risk of becoming zinc insufficient due, in part, to high fetal requirements for zinc. Lactation can also deplete maternal zinc stores. For those reasons, the RDA for zinc is higher for pregnant and lactating women than for other women.
Older Infants Who Are Exclusively Breastfed
Breastmilk provides sufficient zinc (2 mg/day) for the first 4-6 months of life but does not provide recommended amounts of zinc for infants aged 7-12 months, who need 3 mg/day. In addition to breastmilk, infants aged 7-12 months should consume age-appropriate foods or formula containing zinc. Zinc supplementation has improved the growth rate in some children who demonstrate mild-to-moderate growth failure and who have a zinc deficiency.
People with Sickle Cell Disease
Results from a large cross-sectional survey suggest 44% of children with sickle cell disease have a low plasma zinc concentration, possibly due to increased nutrient requirements and/or poor nutritional status. Zinc deficiency also affects approximately 60%-70% of adults with sickle cell disease. Zinc supplementation has been shown to improve growth in children with sickle cell disease.
Approximately 30%-50% of alcoholics have low zinc status because ethanol consumption decreases intestinal absorption of zinc and increases urinary zinc excretion. In addition, the variety and amount of food consumed by many alcoholics is limited, leading to inadequate zinc intake.
Foods Containing Zinc
A wide variety of foods in the American diet contain zinc. Oysters contain more zinc per serving than any other food, but red meat and poultry provide the majority of zinc. Other good food sources include chickpeas, kidney beans, almonds, cashews, certain types of seafood, such as crab and lobster, whole grains, fortified breakfast cereals, cheese, milk, and yogurt.
Aside from eating well-balanced, nutritious foods everyday, if you feel you are at risk of zinc deficiency, talk to your health care provider.
In Health and Happiness,
Kelly Harrington, MS, RDN
Registered Dietitian Nutritionist for Healthy Goods
1. National Institutes of Health; Office of Dietary Supplements. Zinc: Fact Sheet for Health Professionals