Vitamin and mineral supplement use by older rural adults

Vitamin and mineral supplement products are widely consumed by older adults. This study describes supplement product use in a multiethnic rural population, relates supplement usage to dietary nutrient intake, and determines predictors of supplement usage.

Data are from a population-based sample of 130 community-dwelling adults aged 70 years and older in two rural North Carolina counties. The sample was 34% African American, 36% European American, and 30% Native American. Interviewer-administered semiquantitative food frequency questionnaires were used to obtain data on usual diet and supplement use. In-home interviews allowed verification of supplement composition. Intakes from diet and supplement products were examined for vitamins A, E, B6, C, folate, iron, zinc, and calcium.

Of those who participated in the study, 47% reported using one or more supplement products. African Americans were significantly less likely to take supplements than Native Americans or European Americans. Based on dietary intakes, 65% of the participants were deficient (<2/3 recommended dietary allowance [RDA]) for at least one nutrient. The use of supplement products for the eight nutrients investigated was not related to dietary nutrient deficiency. For all nutrients investigated, except iron and calcium, a greater proportion of those without dietary deficiency took a supplement product than those with deficiency. Using logistic regression, ethnicity (European American and Native American), and gender (women) were significant predictors of supplement use.

These findings suggest that although both dietary deficiencies of vitamins and minerals and supplement use are relatively high in this population, there is no association between supplement use and deficient dietary intakes for the eight nutrients examined. Health care providers should be aware that nutritional counseling and guidance on appropriate supplement usage is needed in this population.