Zinc
Zinc is a part of every living cell in the body; it’s essential for optimal growth and development, supports the immune system, and is required by enzymes involved in most major metabolic pathways. Mild zinc deficiency can have adverse health effects on pregnancy outcomes, growth, cognition, and immune function.1,2
1. Institute of Medicine. Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium and Zinc. National Academy Press, Washington. 2001
2. Hambridge M. J Nutr, 2000:130:1344S-1349S
Dietary Zinc Intakes
Zinc is found in a wide variety of foods including beef, poultry, fish, seafood, legumes, and grain products. Red meats are particularly rich in zinc. Beef is one of nature’s richest sources of highly available zinc with 8.6mg per 100g serving.*
Various factors such as health conditions (e.g. Crohn’s), body stores (more zinc is absorbed when stores are low) and dietary intake can influence overall zinc status.1,2
Zinc Enhancers
The amount and quality of protein in the diet influences bioavailability of zinc; high quality protein from animal foods improves zinc absorption from plant foods.1
Increasing the amount of red meat in the diet improves overall bioavailability of zinc.3 Recent research on how dietary patterns influence zinc status found that the mean serum zinc of red meat eaters was significantly higher than that of non-red meat eaters.4
Zinc Inhibitors
Zinc absorption is inhibited primarily by phytates found in plant foods such as soy products, whole grains and legumes.1,5 Plant foods are an important part of healthy eating; balancing them with high-quality animal protein helps increase zinc absorption.
High intakes of iron at levels found in some supplements, as well as calcium phosphate supplements may also decrease zinc absorption.1
* 100g cooked, lean only beef based on composite nutrient values.
1. Institute of Medicine. Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium and Zinc. National Academy Press, Washington. 2001
2. King JC and Keen CL. Modern Nutrition in Health and Disease, 9th Edition. Baltimore: Williams and Wilkins. 1999. P. 223-239.
3. Johnson, JM and Walker PM. J Am Diet Assoc, 1992; 92:1474-1478.
4. Gibson RS et al. Br J Nutr, 2001;86(1):71-80.
5. Bo Lonnerdal. J Nutr, 2000;130(suppl. 5s):1367S-1373S.
Health Implications
Children
Young children are especially vulnerable to zinc deficiency; getting enough zinc can be challenging for young children with smaller appetites.
Even mild zinc deficiency may lower resistance to infection, impact cognition, and limit normal bone function and growth in infants, children and teens.1,2
Practice Point
Parents should be encouraged to serve their children 1 to 2 servings from the Meat and Alternatives group, especially zinc-rich foods. One serving of beef will meet the daily zinc needs of a young child (1-8 years). A serving is about the size of two lipsticks. Provide guidance on child-friendly zinc-rich foods, such as meatballs, meatloaf and tender lean beef in soups and stews.
Vegetarians
Achieving adequate zinc intakes can be of particular challenge for those who restrict foods of animal origin. Vegetarians who limit zinc-rich foods, like beef, poultry, fish or seafood, may need up to 50% more zinc.3
Strict vegetarians, especially parents of vegan infants, should consult a registered dietitian regarding menu planning. Older vegan infants may need zinc supplements as well as reliable sources of iron and vitamins D and B12.4
1. King JC. Am J Clin Nutr 1996;71(5 Suppl):1334S-1343S
2. Hambridge M. J Nutr 2000;130:1344S-1349S
3. Institute of Medicine. Dietary Reference Intakes for Vitamin A, Vitamin K, Arsenic, Boron, Chromium, Copper, Iodine, Iron, Manganese, Molybdenum, Nickel, Silicon, Vanadium and Zinc. National Academy Press, Washington. 2001
4. Mangels AR and Messina V. J Am Diet Assoc, 2001:101(6):670-677.