With continued vitamin insufficiency, xerophthalmia and keratomalacia occur with perforation and ultimately cause blindness. This is especially common in the children of underdeveloped countries, where vitamin A deficiency may be responsible for an estimated 250,000 cases of blindness annually. Although most symptoms of vitamin A deficiency improve with vitamin A supplementation, there may be a permanent stunting of growth if the epiphyseal, or growth, plates close prematurely in bones.
Data collected from the 50,828 women enrolled in the Nurses’ Health Study b researchers at the Brigham and Women’s Hospital in Boston suggest that consuming foods high in vitamins A and C may reduce the incidence of cataracts. Antioxidant rich vegetables such as spinach, sweet potatoes and squash appear to proteins in the lens that lead to the formation of cataracts.
Measles seems to have a poorer prognosis in children who are vitamin A deficient. Children with severe measles infections should be given vitamin supplementation.
One study of AIDS patients demonstrated that individuals with vitamin A deficiency died sooner than those with normal levels of the vitamin.
Dosage
The liver stores several months’ supply of vitamin A in well nourished individuals. Protein and possibly zinc may be involved in the utilization of the liver stores. Rarely should adult doses exceeding 25,00 I.U. daily be taken unless a deficiency is especially severe.