Association of smoking with serum and dietary levels of antioxidants in adults: NHANES III, 1988-1994

Objectives. This study examined the association of smoking with serum level s and dietary intakes of antioxidants in a nationally representative sample . Methods. This study classified 7873 apparently healthy adults aged 17 to 50 years from National Health and Nutrition Examination Survey III (NHANES II I) data as nonsmokers or as smokers if their serum cotinine levels were eit her lower than 14 ng/mL or 14 ng/mL or greater, respectively. SUDAAN softwa re was used for the statistical analysis. Results. Smokers of both sexes had significantly (P < .001) lower serum lev els of vitamin C, alpha -carotene, beta -carotene, beta -cryptoxanthin, and lutein/zeaxanthin. Reduction in the serum vitamin E, lycopene, and seleniu m levels in smokers was slight. Smokers also had significantly lower dietar y intakes of vitamin C and beta -carotene. A significant (P<.001) inverse r elation was found between serum vitamin C and <beta>-carotene levels and co tinine levels independent of diet effect, and a positive relation (P<.001) was found between serum levels and dietary intakes. Conclusions. Antioxidants appear to have differing declines in serum levels as a result of reduced dietary intakes and the effects of smoking.