Enthusiasm vs. evidence
“I agree with these concerns and think that the enthusiasm for these supplements outpaces the evidence from rigorous randomized clinical trials,” JoAnn E. Manson, MD, MPH, DrPH, chief of the Division of Preventive Medicine at Brigham and Women’s Hospital, Boston, said in an interview. “Results of the observational studies have tended to be much more favorable than the randomized clinical trials.
“The labels can be very misleading to the general public,” she noted. “People are confronted with a dizzying array of dietary supplements, many of which include structure/function claims that require minimal, if any, evidence of efficacy. Clinicians should emphasize with patients that a dietary supplement will never be a substitute for a heart-healthy diet and that many supplements are not helpful for people who already follow a healthy diet,” she said.
The VITAL trial, for which Dr. Manson was principal investigator, showed that supplementation with n-3 fatty acids did not lead to a lower incidence of major cardiovascular events or cancer, compared with placebo.
A subgroup analysis showed that 1 g/d conferred a 20% reduction in major events only for participants who ate less than 1.5 servings of fish per week, Dr. Manson said.
Regarding supplement labels, clinicians should recommend that patients look for a U.S. Pharmacopoeia seal or a seal from the National Science Foundation or ConsumerLab, she advised. These seals ensure that the product has been audited for purity and consistency of content and that the dose in the capsule is consistent with what is on the label.
Dr. Manson also would like to see labels explain that most of the products have not been reviewed by the FDA. “Many members of the general public are misled by these labels into thinking that they’re going to receive health benefits. They’re spending a lot of money on supplements that likely provide no benefit and may even be associated with increased risks.”
No funding for the study was reported. Dr. Navar has received grants from BMS, Esperion, Amgen, and Janssen and personal fees from AstraZeneca, Boehringer Ingelheim, Bayer, BMS, Esperion, Janssen, Eli Lilly, Merck, Silence Therapeutics, Novo Nordisk, Novartis, New Amsterdam, and Pfizer outside the submitted work and serves as deputy editor for equity, diversity, and inclusion at JAMA Cardiology.
A version of this article first appeared on Medscape.com.