Vitamin-mineral supplement use: association with dietary intake and iron status of adults

Although vitamin-mineral supplement use is increasing in the United States, few researchers have examined whether supplement users have better nutritional status than do nonusers. Data from 10,515 persons examined in the second National Health and Nutrition Examination Survey (NHANES II) were used to compare mean dietary intakes of several nutrients and food groups, hemoglobin, mean corpuscular volume, transferrin saturation, erythrocyte protoporphyrin, and serum ferritin between regular supplement users and nonusers aged 16 to 74 years. Prevalences of impaired iron status also were compared between user groups. Users consumed more vitamin C and ate fruits and vegetables more frequently than did nonusers in all age/sex groups. No significant differences in mean iron status indicators were observed except in the 65 to 74 year age/sex groups: transferrin saturation among men and mean corpuscular volume, erythrocyte protoporphyrin, and serum ferritin among women. In each case, users had higher values than nonusers in this age group. Prevalences of impaired iron status did not differ between users and nonusers in any age/sex group. In general, iron status was not associated with supplement use.