Background: The safety and efficacy of dietary supplements is of growing concern to regulators, health-care providers and consumers. Few scientific data exist on clinical effects and potential toxicities of marketed products. Harmful supplements may not be identified for months or years with existing adverse event monitoring mechanisms. Retrospective review of poison center statistics to capture supplement-associated toxicity also has limitations.
Methods: We collaborated with the FDA Center for Food Safety and Nutrition (CFSAN) to conduct a 1-year prospective surveillance study of dietary supplement-related poison control center calls in 2006. Prompt follow-up of symptomatic cases, laboratory analysis of implicated dietary supplements, and causality assessment by a case review expert panel were performed.
Results: Of 275 dietary supplements calls, 41% involved symptomatic exposures; and two-thirds were rated as probably or possibly related to supplement use. Eight adverse events required hospital admission. Sympathomimetic toxicity was most common, with caffeine products accounting for 47%, and yohimbe products accounting for 18% of supplement-related symptomatic cases. Suspected drug-herb interactions occurred in 6 cases, including yohimbe co-ingested with buproprion (1) and methamphetamine (3), and additive anticoagulant/antiplatelet effects of NSAIDs taken with fish oils (1) and ginkgo (1). Laboratory analysis identified a pharmacologically active substance in 4 cases; supplement toxicity was ruled unlikely when analytical testing was negative in 5 cases.
Conclusion: Most supplement-related adverse events were minor. Clinically significant toxic effects were most frequently reported with caffeine and yohimbe-containing products. Active surveillance of poison control center reports of dietary supplement adverse events enables rapid detection of potentially harmful products, which may facilitate regulatory oversight.