Relations between diet and nuclear opacities in the lens of the eye were investigated in a population-based cohort of middle-aged and older adults who lived in Beaver Dam, Wisconsin. Nuclear sclerosis was assessed from photographs of the lens taken during 1988-1990 in 1,919 persons in the Beaver Dam Eye Study. Diets in the past (1978-1980) were assessed retrospectively with the use of a food frequency questionnaire in home interviews. Relations with intake of foods and nutrients were evaluated using logistic regression analyses. In men, after controlling for age, smoking, and heavy drinking, intakes of numerous nutrients in the highest versus lowest quintile were associated with 40-50 percent reduced odds of more severe nuclear sclerosis. Relations with some nutrients (vitamins A, C, and E, riboflavin, thiamin, niacin) were at least partly explained by previously identified inverse associations with multivitamin use. Relations with other nutrients (folate, alpha-carotene, and dietary fiber) appeared to reflect associations with intake of foods, particularly vegetables. Inverse associations with individual nutrients and foods were often weaker or nonexistent in women. These data indicate that the intake of vitamin supplements (in men and women) and certain foods (particularly in men) may explain associations of several nutrients with risk for nuclear sclerosis.