Zinc

Poor growthAcne-like rashHair lossDiarrheaDelayed sexual maturationImpotenceSterilityEye lesionsLoss of appetiteReduced sense of taste and smellSkin lesions and inflammationReduced resistance to infectionsPoor wound healingMental confusionPoor learning abilityChanges in hair and nailsAnemia People who may be at risk for a zinc deficiency include: People who eat very low calorie dietsPregnant womenElderly peopleVegetariansAthletesAlcoholics or others with chronic liver disease People with malnutrition from a variety of causes including cancer and digestive diseases that cause malabsorption and/or diarrhea, for example: Celiac sprueCrohn's diseaseShort bowel syndromeOther conditions treated with nutrition given by vein (parenteral alimentation) Zinc Toxicity Zinc toxicity is rare in the US. However, people who take zinc supplements may reach toxic levels. Oversupplementation with zinc can cause a copper deficiency. Excess zinc may also cause the following: DiarrheaCrampsNauseaVomitingSuppressed immune functionImpaired formation of red blood cellsReduced levels of HDL ("good") cholesterol Major Food Sources Good sources of zinc include foods of animal origin, such as meat, seafood, and liver. Eggs and milk supply zinc in smaller amounts.

Some plant-based foods also contain zinc, but it is not absorbed as well by the body. Phytates found in plants can bind the zinc and decrease its absorption. Persons who eat large amounts of whole grain bread, especially those who eat few zinc containing foods listed below, may be at special risk. The zinc content of the soil in which these foods are grown also affects the zinc content of plant foods. In addition, many whole-grain foods contain zinc, but this zinc is removed when whole grains are refined. Food Serving size Zinc content (mg) Animal foods Oysters, canned 3 ounces 77.4 Beef, ground lean, baked 3 ounces 4.4 Turkey, dark meat, no skin, roasted 3 ounces 3.8 Crab, canned 3 ounces 3.4 Shrimp, cooked with moist heat 3 ounces (15 large shrimp) 1.3 Milk, whole 1 cup 1.0 Egg, large 1 egg 0.5 Plant-based foods Miso (fermented soybean) cup 4.6 Soybean nuts, dry roasted cup 4.1 Wheat germ cup 3.6 Chickpeas, canned 1 cup 2.5 Tofu, raw, firm cup 2.0 Pinto beans, canned 1 cup 1.7 Sunflower seeds, dry roasted 1 ounce 1.5 Mushrooms, shiitake, dried 4 mushrooms 1.2 Almonds, dry roasted 1 ounce 1.0 Peanut butter 2 tablespoons 0.9 Spinach, boiled cup 0.7 Whole-wheat bread 1 slice 0.5 Health Implications Infections and Wound Healing

Sufficient levels of zinc are essential for a properly functioning immune system. For example, zinc is required for the development and activity of T-lymphocytes, which are a type of white blood cell that helps fight infection.When people deficient in zinc are given zinc supplements, biological markers of immunity improve. These effects are most clearly seen among children in emerging nationswhen given zinc supplementation, they experience shorter courses of infectious diarrhea and may have less serious problems from pneumonia.However, if someone is not deficient in zinc, taking zinc supplements does not improve wound healing or other functions of the immune system. The Common ColdZinc lozenges and nasal sprays may help to decrease the duration and severity of cold symptoms. They are believed to directly inhibit viruses in the nose and throat. However, this topic is still controversial, since the findings from scientific studies have been mixed.Those studies that have found a positive effect suggest beginning zinc at the first sign of a cold. The recommended dose is 13 to 23 mg of zinc as zinc gluconate or zinc acetate every 2 hours. This treatment should continue until symptoms subside, but never for longer than two weeks.

Also, lozenges that have citric acid or tartaric acid should be avoided. These acids are often added to improve flavor, but they can block zinc's antiviral action. Absorption of Calcium, Iron, and CopperMinerals can compete with one another for absorption in the body. This is especially a concern when they are taken at high doses, such as those in supplements. If you take calcium supplements but consume little or no zinc, you might need to take a multivitamin/mineral containing zinc. Most multivitamin/mineral pills contain 100% of the RDA for zinc. Large doses of zinc can interfere with the body's absorption of copper and iron, other minerals that are essential to immune function. If you are taking a zinc supplement, talk to your doctor about your need for other supplements. Resources: American Dietetic Associationhttp://www.eatright.org/ National Institutes of Healthhttp://www.nih.gov/ References: The American Dietetic Association's Complete Food & Nutrition Guide. Chronimed Publishing; 1998. Facts about dietary supplements. National Institutes of Health website. Available at: http://www.nih.gov/.

The Nutrition Desk Reference . Keats Publishing; 1995. Perspectives in Nutrition. 2nd ed. Mosby; 1993. Last reviewed October 2007 by Rosalyn Carson-DeWitt, MD Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.