The interest with the role of zinc on immune function may arise from familiarity with the research associating consumption of zinc lozenges with decreased duration of cold symptoms. While it is well known that zinc is associated with immune function, zinc plays an important role in protein synthesis, enzyme function, wound healing and DNA synthesis. Zinc plays an important role in maintaining the integrity of the gastrointestinal tract. The integrity of the gastrointestinal tract has been shown to have a significant influence immune function.
The Recommended Dietary Allowance (RDA) for zinc varies based on age and gender. The RDA for zinc for an adult male (19 years and older) is 11mg and 8 mg for an adult female (19 years and older). The average healthy person should seek out food sources of zinc to meet their daily needs. Good sources of zinc are abundant in the typical American diet and include 3 ounces braised chuck roast (7mg), 3 ounces Alaska King Crab (6.5mg), and 3 ounces beef patty (5.3mg). Good sources of zinc include ¾ cup fortified cereal (3.8 mg), 3 oz pork loin (2.9 mg), ½ cup baked beans (2.3 mg), and 3 ounces dark chicken meat (2.4 mg). Additional sources that provide 1.0-1.5 mg/serving include: yogurt, 1 ounce cashews, ½ cup oatmeal, ½ cup chickpeas, 1 ounce Swiss cheese, and 1-cup of nonfat milk. The bioavailability of zinc is highest when consumed from an animal source. Plant sources of zinc have lower absorption due to the presence of phytates in legumes and whole grains.
While the typical American diet generally provides adequate quantities of zinc to preserve its essential functions, certain diets or medical conditions may contribute to zinc deficiency. Adherence to a vegan lifestyle can contribute to increasing risk for zinc deficiency due to lower absorption of zinc in plant-based food sources. Careful attention to food preparation and selection techniques can minimize this risk. Individuals following a vegan lifestyle are instructed to soak beans, grains, and seeds to increase the availability of plant-based zinc. Additionally, they can be instructed to consume leavened bread products. Another group of individuals at risk for zinc deficiency are those with gastrointestinal conditions such as inflammatory bowel disease, short bowel syndrome, or poorly controlled or newly diagnosed Celiac Disease. These conditions contribute to poor absorption of zinc as well as increased losses of zinc. Individuals with these conditions should be evaluated by their health provider for zinc deficiency as zinc supplementation may be necessary.
As with many vitamins and minerals, many studies support food sources as best sources of vitamins and minerals for meeting daily needs. Vitamin and mineral supplementation is generally reserved for individuals with a diagnosed deficiency. Zinc toxicity from excessive supplementation can result in nausea, vomiting, decreased copper, and changes in iron function.
What should you do if you think you are not getting adequate zinc in your diet? First, evaluate your current diet for adequacy using a nutrition analysis tool such as Choose My Plate. Add one or two sources of fortified food sources to your current diet. If you have a gastrointestinal disease or follow a vegan diet and are concerned about the potential for zinc deficiency visit your health professional for further evaluation prior to starting supplementation. They will evaluate blood work for deficiency and prescribe an appropriate zinc supplement based on your specific needs. A Registered Dietitian is specially trained to evaluate the diet based on an individuals specific medical and genetic needs and can provide further personalized recommendations on maximizing food choices to meet all your vitamin and mineral requirements.
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