Association of dietary supplement use with specific micronutrient intakes among middle-aged American men and women: the INTERMAP study

Objective To assess dietary supplement use and its association with micronutrient intakes and adequacy among 2,195 US men and women aged 40 to 59 years from eight diverse population samples surveyed by the International Population Study on Macronutrients and Blood Pressure. Design Four 24-hour dietary recalls were collected, including information on dietary supplements. The Nutrition Data System (NDS) was used for nutrient analyses. Supplements not in NDS were classified separately (non-NDS). Intake of non-NDS supplements was documented. Participants were classified as not supplement users and supplement users, subclassified--due to concerns about nutritional value--as users of NDS supplements only (mostly vitamins and minerals) and users of non-NDS supplements (eg, botanicals, animal products, and enzymes). To assess effects of supplement use on micronutrient intake and adequacy, mean intakes from supplements, foods, and foods plus supplements were compared with Dietary Reference Intakes. Participants Two thousand one hundred ninety-five US participants; 1,136 used supplements. Statistical analyses [chi square] tests, multivariate logistic regression, and means were used to assess differences in and factors related to supplement use and to determine dietary adequacy. Results Supplement use was more common among women, older participants, more educated participants, and Asian Americans. Body mass index and current cigarette smoking were significantly and inversely associated with supplement use; past smoking and education were significantly and positively associated with supplement use. Intake from foods plus supplements was considerably higher than from foods alone for vitamins A, C, and E; niacin; folate; and iron. Conclusions Supplement use is common among middle-aged Americans and sizably increases daily intakes of several micronutrients. These data underscore the importance of dietary supplement assessment. J Am Diet Assoc. 2005;105:1106-1114.