Zinc, a mineral essential for growth, development and immune function, may help adolescents do better in school. In a 10-week study, more than 200 seventh-graders drank either fruit juice fortified with zinc or juice without the supplement. During that time, they took various cognitive tests such as visual memory and word recognition and performed tasks that required attention and vigilance. Those who drank the zinc-supplemented juice scored better than those who drank the regular juice. However, test performance didn’t improve significantly among kids whose diets already met the recommended daily allowance for zinc. These results may prompt a review of the recommended intake during the teen years—a time of rapid growth and development. Good food sources of zinc include red meats, poultry, beans, nuts, whole grains and some seafood.