200667 Scientific support for dietary supplements: A case study in conflicted science, serious harm, and poor post-market monitoring

Sunday, November 8, 2009

Ano L. Lobb, MPH , Independent public health consultant, Barre, VT
Catherine C. Machalaba, BA , Dartmouth Institute for Health Policy and Clinical Practice, Dartmouth Medical School, Lebanon, NH
Background: Dietary supplements are used by up to 73% of the US population, 4% of whom report experiencing adverse events. An estimated 15% of Americans use weight-loss supplements that often contain potent pharmacologically active ingredients. US Consumers generally assume products are safe and effective, and manufacturers may cite evidence to support such claims. But pre-market trials establishing safety and efficacy are not required in the US, and ingredients do not need to be GRAS (generally regarded as safe). By comparison, governments in Canada and Europe exercise greater regulatory control to protect the public from harm and inform them of effectiveness. There is evidence that weight-loss supplements can be harmful, and of industry efforts to build a body of scientific literature supporting product safety and effectiveness. Reliable post-market monitoring for adverse events is lacking in the US, and once such events are identified, previous experience with harmful supplements has shown US regulators to be less willing to intervene than their counterparts in Canada and Europe. This case study evaluates the influence of industry in studies of the top selling weight-loss supplement in the US, and the quality of post-market surveillance for adverse events associated with that product.

Methods: Pubmed searches using proprietary product names, reviews of product websites and FDA's Medwatch adverse events surveillance system.

Results: 26 unique published papers were located, 14 sharing one author employed by the manufacturer of the proprietary active ingredient. Papers by this author were generally more supportive of product safety and efficacy than papers by neutral authors. In 11 studies available for review, author's academic affiliation was noted in all 11, commercial affiliation in only 3, the product's commercial name was used in 9, product manufacturer noted in 6. No papers disclosed a funding source, though at least 2 received manufacturer funding. A single paper provided sufficient disclosure to identify the author as being affiliated with the manufacturer of the product being evaluated. A search of Pubmed located 8 published cases of severe adverse events associated with the product, including hepatoxicity, rhabdomyolosis and hypertensive retinopathy. No adverse event reports were located in Medwatch.

Conclusion: Weight-loss supplements may cause serious adverse events, and data supporting commercial claims lacks adequate conflict of interest disclosure. Limited pre-market safety requirements and poor post-market surveillance of dietary supplements in the US may endanger the public's health.

Learning Objectives:
1. Describe the reasons for, and the overall scale of dietary supplement use. 2. Explain examples of weaknesses in the scientific peer-review system and how they apply to dietary supplement data. 3. Discuss a past example of harm from supplements, and differing regulatory response. 4. Compare the post-market response to harmful supplements in the US and Canada and Europe.

Keywords: Safety, Risk Factors

Presenting author's disclosure statement:

Qualified on the content I am responsible for because: I have a Masters of Public Health, and 9 years of evidenced-based research experience related to health, healthcare, pharmaceuticals and dietary supplements. I have lectured on related materials at Darmtouth Medical School, where I have been a co-course director for a course in their public health program. I have also published material related to dietary supplements and pharmaceuticals in the peer-reviewed literature, and was presenter at APHA in 2008.
Any relevant financial relationships? No

I agree to comply with the American Public Health Association Conflict of Interest and Commercial Support Guidelines, and to disclose to the participants any off-label or experimental uses of a commercial product or service discussed in my presentation.