This study delineates demographic, lifestyle, dietary and health factors associated with the use of supplements at varying levels.

Data are from a population-based cohort of 2,152 middle-to older-age adults living in Beaver Dam, Wisconsin.

Information was collected by in-person interviews between 1988-1990.

Associations were adjusted for gender and age.

Use of supplements was more prevalent among women, persons with more than 12 years of education, those with relatively low body mass indices, persons with active lifestyles, and persons who never smoked as compared to current smokers (P<0.05).

Supplement users had higher intakes of most of the micronutrients from food that were examined in this study, including the antioxidant vitamins C and E and certain carotenoids (P<0.05).

Intakes of dairy products and also foods that are important sources of vitamin C and carotenoids were higher among users of supplements, but relationships differed by gender and by the type and level of supplement intake.

These findings suggest that several factors need to be considered potential confounders in observational studies that examine the etiologic role of supplements in the occurrence of chronic disease.