Are dietary supplements for real or just placebos?

Dietary supplements are a $40 billion industry in the United States with three quarters of adults and one-third of children taking supplements based on promises that they can maximize health.  

In response to the widespread use of supplements and the rapid growth of the industry, the U.S. Food And Drug Administration recently announced new plans to regulate the safety of supplements on the market.

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It is certainly within the purview of the FDA to protect consumers from false claims of health benefits and from potentially dangerous compounds in these supplements. In the announcement, an FDA physician comments on his/her use of supplements and the benefits of supplements.

Regulatory bodies concerned with drug and supplement safety are not traditionally tasked with making recommendations for use, but the recent announcement with that personal vignette subtly blurs that line.

Dietary supplements are manufactured substances typically taken by mouth in pill, liquid or powdered form that include extracted or synthetic nutrients that are intended to enhance dietary intake from whole foods.

Supplements promise a range of health benefits from weight loss, enhanced mood and better sleep to prevention from the major causes of death — cardiovascular diseases, cancer and chronic lung diseases.

Despite the widespread use of dietary supplements, evidence of their effectiveness is slim.

When 18 studies testing the effectiveness of multivitamin supplementation on risk of cardiovascular disease were pooled together, the overall finding was that multivitamin supplementation did not prevent death from cardiovascular diseases.

One hint about why these results are not consistent with popular opinion is that when the analysis was separated between those studies — that simply asked participants about their use of supplements and observed what happened (observational studies) vs. studies that assigned some participants to take supplements and others not to (randomized controlled trials) and tracked outcomes — the results were very different.

In observational studies, supplementation was modestly effective in preventing the development of heart disease. However, in randomized controlled trials those associations disappeared. As it stands, the strongest level of evidence on which medical guidelines are developed the “gold standard” of randomized controlled trials.

On the basis of these and other findings, the American Heart Association recommends that foods should take priority over supplements.

As a participant in the development of diet and lifestyle guidelines in 2006, the strongest evidence for disease prevention was found for a well-rounded diet comprised of fresh vegetables and fruits, lean sources of protein and complex carbohydrates. Recent updates from the AHA also highlight the intake of whole foods to complement a healthy lifestyle that includes regular physical activity and adequate sleep.

Supplements are recommended in certain medically-indicated situations — as every pregnant woman prescribed a prenatal vitamin is aware. Additionally, infants who are exclusively breastfed require iron supplementation. Another common indication for supplementation is for patients who have undergone bariatric surgery. However, these and other medical situations do not apply to the majority of the 170 million adults and even more children who are currently using supplements.

In full disclosure, I do use supplements. Following an injury to my hip, I told my doctor that I would try glucosamine and chondroitin supplements to prevent joint pain. His response was “there is no evidence that it works, but if it makes you feel better go ahead.”

With that endorsement, I paid $40 for one month supply — and I think my hip feels better. That placebo effect is the reason that there are contradictory results between observational studies and clinical trials and likely the reason why the supplement industry makes billions of dollars each year.

The FDA’s announcement to regulate the claims and safety of dietary supplements is certainly needed and will likely protect many innocent consumers. However, the FDA could do well to also emphasize that dietary supplements may make us feel better, but they are certainly not required for most Americans.

Mercedes Carnethon, Ph.D. is the Mary Harris Thompson professor of preventive medicine and chief of the division of epidemiology at the Northwestern University Feinberg School of Medicine and a Public Voices Fellow through The OpEd Project.