Science of weight loss supplements: Compromised by conflicts of interest?

Table 1 Selected studies supporting popular weight loss supplements

Xenadrine

Advertisements for this popular and widely advertised weight loss supplement cite a published study supportive of its effectiveness[11]. In addition to being small (n = 47) and of short duration (6 wk), the study lacks financial disclosure, or any mention of a funding source

LeptiCore

Marketing text for this weight loss product cites a published study of 62 participants followed for 6 wk who reportedly experienced significant reductions in weight, body fat, and other metrics associated with chronic disease, such as cholesterol and waist size[12]. The study does not disclose a funding source, beyond the name of the company that provided the tested substance. The paper states that the authors have no competing interests, though one author appears to be a chief scientific officer of a dietary supplement company1, and appears on US Patent Office2 filings as the inventor of a weight loss supplement whose patent is held by the same supplement company the author appears to be employed by (The patent was granted in 2010, and originally filed in 2000)

Hydroxycut Advanced

Hydroxycut was the top selling weight loss supplement in the US, then withdrawn from the market after being linked to 23 cases of liver toxicity and one death[3]. Marketing materials for Hydroxycut cited two published studies asserting product effectiveness that were small, of short duration, reported no serious side effects[13,14], and did not disclose relationships between authors and the product manufacturer[15] or that funding was received from the product manufacturer[16]

Hydroxycut has been renamed Hydroxycut Advanced, reformulated and returned to market, distributed by IHS. An active ingredient suspected of causing liver toxicity in the original formulation, Garcinia cambogia[2,3], has been removed and replaced with other ingredients, including CQ. At least 3 recently published studies support the safety and effectiveness of CQ for weight loss but lack financial disclosures or funding sources, beyond mentioning that the CQ being tested was provided by GHA[17-19]. The studies all share an author who is listed as a chief scientific officer for GHA1 on internet sites, but not in the publications in question, and appears on US Patent Office2 filings as the inventor of a weight loss supplement whose patent is held by GHA. IHS and GHA have collaborated in the past, though it is unclear whether the CQ currently used in IHS’s product is provided by GHA

Concerns

1 Small, short term studies, and those funded by industry[7] may over-state product safety and effectiveness

2 A lack of funding source declaration reduces validity of findings, since readers are unable to assess the potential for this type of conflict of interest

3 Being a patent holder for a weight loss supplement should be considered a financial conflict of interest in these cases, since a patent holder may stand to gain financially from scientific reports of supplement effectiveness

4 The undeclared, potential financial or professional relationships between the patent holder/author and the manufacturer of the substance being studied also appears to be a conflict of interest, since the author would have a personal financial interest in the financial success of the product being studied

¹http://www.clinicaltrials.gov, and professional networking websites, accessed May 7, 2010;

²http://www.uspto.gov, accessed May 7, 2010. IHS: Iovate Health Sciences; CQ: Cissus quadrangularis; GHA: Gateway Health Alliances.