Zinc May Increase Stature in Some Growth Hormone-Deficient Children

Healthnotes Newswire (October 16, 2003)—Children with growth hormone (GH) deficiency who receive treatment with GH may significantly increase their growth rate by supplementing with zinc, according to a new study in Journal of Tropical Pediatrics (2003;49:187–8). The benefits of zinc supplementation were limited to GH-deficient children whose initial blood levels of zinc were low.

Growth hormone is the primary hormone responsible for the normal growth of children. Deficiency of GH occurs in approximately 1 in 4,000 children. Known causes of GH deficiency include infection, inherited predisposition, trauma, and some types of brain tumors; however, in more than 66% of children with GH deficiency, the cause cannot be identified. The impairment in growth resulting from GH deficiency may begin in infancy or later in childhood. Most children with GH deficiency fall below the fiftieth percentile on growth charts, compared with normal children. The current treatment is daily or weekly injections of GH by itself or in combination with other hormones. While the treatment is effective, it is very expensive, costing up to $20,000 per year.

In the new study, 24 children between the ages of 5 and 13 years with GH deficiency being treated with GH for at least one year received daily zinc supplementation based on body weight (1 mg per kilogram per day) for six months. Blood levels of zinc were measured in all children prior to zinc treatment. Growth rate was also measured initially and at the conclusion of the study.

Almost 46% of the children in the new study were initially found to be deficient in zinc, while the other 54% had normal blood zinc levels. The growth rate for the children with GH deficiency and zinc deficiency increased from 5.98 cm per year to 7.51 cm per year, a statistically significant change. However, no change was observed in GH deficient children with normal zinc levels. The findings suggest that zinc increases the effectiveness of GH therapy and that blood zinc levels may be useful in determining which children may benefit most from zinc supplementation.

Studies have suggested that zinc deficiency by itself may cause poor development and growth in infants and children. This is most often seen in developing countries, where diets often lack adequate amounts of zinc. Even in the United States, however, according to some studies, more than 50% of people consume less than two-thirds of the recommended dietary allowance (RDA) for zinc. Zinc deficiency may also be associated with decreased immunity, impaired taste sensation, poor wound healing, weight loss, and impaired vision. The RDA is 15 mg per day. Good sources of zinc include meat, eggs, dairy products, seafood, black-eyed peas, tofu, and wheat germ.