Vitamin and Mineral Supplement Use by Older Adults with Complex Medication Needs; Potential for Adverse Drug-Nutrient Interactions

Abstract

Objective: Vitamin and mineral supplements have been increasingly available for decades. The increase in availability of supplements and their use in combination with prescription drugs suggests that the risk of an adverse drug-nutrient interaction has drastically increased. This is especially concerning in populations with greater medication use. The purpose of this study was to assess vitamin and mineral supplement use in older adults with complex medication use to identify supplement use, overuse, and use from multiple sources. A secondary outcome of this study was to assess the potential for adverse drug-nutrient interactions in medically complex patients. Methods: A retrospective chart review was completed on 229 medically-complex patients 50 years of age and older who had new assessments of medications completed between January 2014 and January 19th, 2017 at the University of Saskatchewan Medication Assessment Centre. Results: Data indicate that 76.9% (n = 176) of patients (mean: 69 years) reported using ≥ 1 vitamin and/or mineral supplement daily. Total product count (oral prescriptions, over-the-counter (OTC) products, dietary supplements) ranged from 1-45 per day, with a mean 9.8 and median of 9. The tolerable upper intake level (UL) for nutrients was exceeded by 39.7% (n = 70) of reported supplement users (n = 176). One case exceeded the UL for 6 different nutrients, from supplemental intake alone. Of reported supplement users, 43.2% consumed supplemental nutrients from more than one source, which was significantly associated (p < 0.001) with supplemental nutrient intake at or above the UL. Conclusions: Vitamin and mineral supplement use in conjunction with prescription drugs and OTC products was observed in this population, with reported intake of many supplemental nutrients that exceeded the UL.