Zinc is an essential trace mineral that's important for the immune system and the brain, as well as other parts of the body. In infants, zinc deficiency can delay normal development. At any age, serious zinc deficiency can lead to risk of infections.
Eye-related benefits. Zinc is believed to be important for vision because high levels of the mineral are found in the macula, part of the retina. Zinc enables vitamin A to create a pigment called melanin, which protects the eye. Some studies show that getting enough zinc can help you see better at night.
The iris is a circular, pigmented membrane that provides the eye its color and the opening in the center is the pupil of the eye.
The iris is made up of muscular fibers that control the amount of light entering the pupil so that you can see clearly. The iris accomplishes this task by making the pupil smaller in bright light and larger in dim light.
In some people, the iris can become inflamed. This is termed iritis.
In the Age-Related Eye Disease Study (AREDS), people at high risk of developing advanced stages of age-related macular degeneration (AMD), a leading cause of vision loss, lowered their risk by about 25% when treated with a supplement that included certain antioxidants and 80 mg of zinc. In the same high-risk group -- which includes people with intermediate AMD, or advanced AMD in one eye but not the other eye -- the nutrients reduced the risk of vision loss caused by advanced AMD by about 19%. A continuation of the first study, AREDS2, however, showed the protective effect of the supplement's formula was not lessened when the amount zinc was reduced to 25 mg.
Recommended Daily Allowance: 8 mg/day for women; 11 mg/day for men.
Possible risks: Zinc can block the absorption of copper. For that reason, dietary supplements that contain zinc also usually contain extra copper. The American Optometric Association recommends supplements with 2 mg/day of copper for people taking zinc supplements. Zinc can interfere with some antibiotics. Zinc may cause stomach upset in some people, as well as an increased risk of hospitalizations for GU disorders. Talk to your doctor before you start taking a supplement that includes extra zinc.