Medical Health Encyclopedia

Antioxidant vitamins C and E. Because of the role oxidants may play in cataract formation, researchers are investigating the benefits of antioxidant vitamins and other food chemicals. Vitamins C, E, and riboflavin (a B vitamin), for example, are helpful in preserving glutathione levels, an enzyme that helps protect against oxidation in the eye. Low levels of vitamin C in the lens of the eye have been particularly strong predictors of cataracts. There is also some evidence that ultraviolet B radiation interacts with deficiencies in certain antioxidants, such as vitamin E and zinc, to increase damage in the corneas and lenses of the eye.

Evidence on the benefits of supplements of vitamin E or C, or vitamin-rich foods, is conflicting. For example, in two identically constructed trials in the US and Britain, the American group derived apparent benefits from vitamins E, C, and beta carotene while the British group reported very little cataract protection. A 2005 study suggested that long-term use of vitamin E supplements may slow cataract development. However, in a major on-going American study called the Age-Related Eye Disease Study (AREDS), researchers reported no difference in the incidence of cataracts after 7 years in people who took the antioxidant vitamins compared to those who took sham vitamins.

High doses of vitamins may have harmful effects. It is always wise, in any case, to pursue a healthy diet that is low in fats, high in complex carbohydrates, and rich in fruits and vegetables.

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B vitamins. Some studies report some protection from a number of B vitamins, including vitamins B1 (thiamin) B2 (riboflavin), B3 (niacin) and B12 (folate). Riboflavin, for example, plays a critical role in the production of glutathione, an enzyme that helps protect against oxidation in the eye. All forms of vitamin B are widely available in dairy products, fortified grains, and meat.