Zinc

What does Zinc do?

Zinc is a component of more than 300 enzymes that are needed to repair wounds, maintain fertility, synthesize protein, help cells reproduce, preserve vision, boost immunity, and protect against free radicals, among other functions.

Zinc lozenges shorten the duration of cold symptoms for adults in most double blind studies using proper methodology, though this effect has not been reported in children. Most successful studies have used zinc gluconate or zinc gluconate-glycine lozenges containing 15–25 mg of zinc per lozenge.

Cold sufferers should avoid lozenges that contain citric acid or tartaric acid, substances that may interfere with efficacy and have been used in most trials that fail to get good results. With one exception, trials using forms other than zinc gluconate or zinc gluconate-glycine have failed, as have trials that use insufficient amounts of zinc. Therefore, until more is known, people should only use zinc gluconate or gluconate-glycine. Zinc lozenges are not to be taken long term, but rather only at the onset of a cold and stopped when symptoms have disappeared. The best effect is obtained when lozenges are used at the first sign of a cold: up to ten lozenges per day can be taken for several days during the cold.

Where is Zinc found?

Good sources of zinc include oysters, meat, eggs, seafood, black-eyed peas, tofu, and wheat germ.

Who is likely to be deficient?

Low-income pregnant women and pregnant teenagers are at risk for marginal zinc deficiencies. Supplementing with 25–30 mg per day improves pregnancy outcome in these groups.

The average diet frequently provides less than the recommended daily allowance for zinc. A low-dose supplement (15 mg per day) can fill in dietary gaps. Zinc deficiencies are more common in alcoholics and individuals with sickle cell anemia, malabsorption problems, and chronic kidney disease.