Subpar evidence, booming industry
“Annual sales of dietary supplements for weight loss are booming with an industry valued at $30 billion worldwide, despite subpar evidence” of efficacy, the commentary authors wrote by way of background.
After the Dietary Supplement Health and Education Act of 1994, the National Institutes of Health’s Office of Dietary Supplements was established “to strengthen the knowledge and understanding of dietary supplements by evaluating scientific information, stimulating and supporting research, and educating the public,” they explained.
However, dietary supplements and alternative therapies are endorsed by influencers and celebrities and marketed as a panacea for obesity and weight gain.
Literature review finds scant evidence
Consumers may believe that the “clinically proven” claims of efficacy of these “natural” weight-loss treatments have been thoroughly evaluated for safety and efficacy by the FDA, and clinicians lack information to counsel patients about this.
Therefore, although the Office of Dietary Supplements’ work has importantly advanced the science, the review authors wrote, members of the Obesity Society believed it was important to evaluate and perform a qualitative synthesis of the evidence for efficacy of non–FDA-regulated weight-loss supplements and alternative therapies to better inform clinicians and consumers.
From more than 20,000 citations of 53 dietary supplements and alternative therapies promoted for weight loss, the researchers identified 314 randomized controlled trials of 14 products that each had at least 5 randomized controlled trials.
The two types of alternative therapies in the review were mind-body interventions – which included behavioral therapies (for example, mindfulness and stress management), hypnosis, meditation, or massage – and acupuncture.
Several popular and widely used products (for example, human chorionic gonadotropin, raspberry ketones, nicotinamide adenine dinucleotide, vitamin infusions) did not meet the predefined number of published randomized controlled trials to be eligible for inclusion in the review.
The greatest number of trials were for acupuncture (45 trials), green tea (38), conjugated linoleic acid (31), ephedra with or without caffeine (31), mind-body therapies (22), and calcium and vitamin D (22). There were fewer trials of garcinia and/or hydroxycitrate (15), chitosan (9), phaseolus (7), pyruvate (7), chocolate/cocoa (6), chromium (6), guar gum (5), and phenylpropylamine (5).
Of the 314 studies, only 52 studies (16.5%) demonstrated that the products were efficacious and low risk, and only 16 studies (0.5%) reported a statistically significant between-group weight loss (0.3-4.93 kg).
For more information, in addition to their review and commentary, the authors refer clinicians to a dietary supplement label database.
The study was supported in part by grants from the National Institute on Aging. Dr. Batsis reported equity in SynchroHealth. Dr. Kidambi reported being the medical director for TOPS Center for Metabolic Health at the Medical College of Wisconsin, which is supported by TOPS. Dr. Kahan reported serving as a consultant for Novo Nordisk, Vivus, Gelesis, and Pfizer.