Recent epidemiologic studies on nutrition and cataract in India, Italy and the United States.

Three independent case-control studies with similar methodologies were conducted in India, the United States and Italy to investigate risk factors by cataract type. Their common objectives were to evaluate risk factors for each cataract type, giving priority to nutritional factors, and to determine whether risk factors differed among cataract types. Data included self-reporting of food frequencies and various biochemical determinations. A higher body mass index was the only nutritional factor found by more than one study to be associated with cataract, being less frequent in cases than in controls. Blood nutritional status from one study showed that a high antioxidant index decreased risk for at least one cataract type, high glucose-6-phosphate dehydrogenase values increased risk for at least one cataract type, a high albumin globulin ratio decreased risk for mixed cataract, and high iron levels decreased risk for cortical cataract. Only one of the three studies found that a high nutritional status, high dietary antioxidant index, and use of multiple vitamin supplements decreased risk for cataract. Findings from these studies suggest socioeconomic and nutritional components to cataract risk, although not consistently across studies or cataract types. Differences between studies may be due to differences in populations and/or data collection methods. Because reducing cataract risk would have major implications for a large segment of the population, clinical trials seem appropriate to confirm and evaluate the potentially modifiable risk factors suggested by these studies.