Increasing trends in elderly persons' use of nonvitamin, nonmineral dietary supplements and concurrent use of medications

Abstract

Objective: Use of nonvitamin, nonmineral dietary supplements among an elderly cohort was surveyed to determine which were the most frequently used, and to report potential medication/supplement interactions observed.

Design: A retrospective review of the use of 22 supplements and prescription/over-the-counter medications was collected annually from 1994 to 1999.

Subjects/setting: Supplement and medication records for an average of 359 male (36%) and female (64%) participants aged 60 to 99 years were reviewed annually. Ethnic distribution was 91% non-Hispanic white, 7% Hispanic, 1% Asian, and 1% African American.

Statistical analyses performed: Descriptive statistics generated included mean, standard deviation, and frequency by percentage. To compare supplement user and nonsupplement user percentages across age groups, the chi 2 test was used. Linear regression was performed to test for longitudinal usage trends of each individual supplement.

Results: By 1999, glucosamine emerged as the most frequently used nonvitamin, nonmineral supplement followed by ginkgo biloba, chondroitin, and garlic. For women, there was a significant linear trend ( P < .05) over time for these 12 supplements: black cohosh, borage, evening primrose, flaxseed oil, chondroitin, dehydroepiandrosterone, garlic, ginkgo biloba, glucosamine, grapeseed extract, hawthorn, and St John's wort. For men, three supplements (alpha lipoic acid, ginkgo biloba, and grape-seed extract) showed a significant linear trend ( P <.05). Potential interactions between supplements and medications were seen for 10 of the 22 supplements surveyed, with a total of 142 potential interactions observed over the 6-year period.

Conclusions: Examining nonvitamin, nonmineral supplement use in combination with prescription/over-the-counter medications in elderly persons is important to identify the potential risks of interactions.