May 24, 2002 -- Some infants and children may benefit from adding zinc to their diets. New data suggest that increasing the amount of this mineral may help children reach a healthy height and weight.
"Because of the important functional consequences of zinc deficiency for children's growth and other health outcomes, interventions to improve zinc ... [in the diet] should be considered in those populations at particularly high risk of zinc deficiency," write the authors of a report published in the June issue of the American Journal of Clinical Nutrition.
Zinc is a mineral found in a variety of foods such as red meat, whole-grain breads and cereals, dried beans, and seafood. It is also found in small amounts in breast milk.
Zinc is vital for the normal growth and development of the reproductive organs and brain and plays a role in the normal functioning of the immune system and many other processes in the body. Recently, zinc deficiency has been linked to decreased growth, increased colds and infections, impaired memory, learning disabilities, and poor attention span. The deficiency is a major problem in developing countries; for instance, 70% of school age children in Thailand are deficient in zinc.
In the U.S., zinc deficiency in children is not well recognized, although it affects an estimated 6% of girls and 10% of boys overall. Disadvantaged children are especially at risk -- more than 50% of poor children and 30% of non-poor children aged 1-5 get less than 70% of the Recommended Dietary Allowance of zinc (10 milligrams per day for children). In fact, recent data suggest that of 16 key nutrients, more children were deficient in zinc than in any other nutrient.
This new report looked at 33 studies on the effects of zinc supplementation on children up to 10 years old that were published between 1976 and 2001.
Overall, zinc supplementation produced very significant positive effects on both height and weight measures of the children. And the effect was even greater among children who already suffered from stunted growth or were underweight.
Researchers say it is hard to quantify the impact because the effects vary according to the age of the child, duration of supplementation, and other factors. But they cite the example of a Guatemalan study that found three years of zinc supplementation (from 3 to 36 months of age) was responsible for nearly an inch in additional growth.
Currently, scientists do not believe there is enough data to recommend widespread zinc supplementation in U.S. children as other studies of zinc's benefits have been inconclusive. In addition, scientists are unsure as to how much is enough; too much zinc can be as dangerous as a deficiency.
Adequate zinc can be obtained thorough a well-balanced diet of a variety of foods. Those foods include red meat, nuts, shellfish, potatoes with skins, beans, and mushrooms.