Supplementation with zinc plus vitamin A, may restore night vision. Zinc supplementation without the vitamin A does not have this effect. This, according to a study published in the American Journal of Clinical Nutrition(May, 2001 issue). The study involved 202 pregnant women from Southern Nepal. The subjects had night blindness and were divided into six groups. The groups received combinations of beta carotene, vitamin A and zinc; or a placebo. Among women with low levels of zinc in their serum, the combination of vitamin A and zinc was four time more effective than in the placebo group that received no zinc.