New study maligns dietary supplements as ineffective for cardiovascular outcomes

A recent study published in the Annals of Internal Medicine is dismissive of dietary supplements for preventing mortality and improving cardiovascular disease outcomes. The study reviews evidence from nine systematic reviews and four new randomized controlled trials encompassing a total of 277 trials, 24 interventions, and 992,129 participants.

Results showed that there was moderate-certainty evidence that reduced salt intake decreased risk of all-cause mortality in normotensive participants, and low-certainty evidence that omega-3s were associated with reduced risk of myocardial infarction and coronary heart disease. Folic acid showed low-certainty evidence of lowering the risk of stroke, but there was moderate-certainty evidence that calcium combined with vitamin D was associated with an increased risk of stroke. According to the study, supplementation with other nutritional supplements, such as vitamin B6, vitamin A, multivitamins, antioxidants, and iron and dietary interventions, such as reduced fat intake, had no significant effect on mortality or cardiovascular disease outcomes.

The industry is taking the study to task. The Council for Responsible Nutrition (CRN; Washington, D.C.), for example, is criticizing the study’s exclusion of observational, or epidemiological, studies. “The [study, accompanying editorial, and video] lack insight from any nutrition-based medical professional or expert with knowledge or appreciation of nutrition research. The study is a Systematic Review of past Randomized Control Trials (RCTs) and meta-analyses of RCTs with absolutely no observational studies included,” explains Steve Mister, president and CEO of CRN, in a press release. “Exclusion of observational, or epidemiological, studies is a major limitation, as Epidemiological data are critical and serve as the basis of many recommendations made in the Dietary Guidelines for Americans.”

The Global Organization for EPA and DHA Omega-3 (GOED;) also reached out to members, expressing concern for the study, and its characterization of omega-3’s heart health benefits as “uncertain at best.” The organization said in a newsletter that the study downplayed the 7% risk reduction for cardiovascular mortality because the results just missed statistical significance. However, GOED’s own commissioned meta-analysis published two years ago found a similar 8% reduction that was statistically significant. The organization also points out that one of the studies cited in the editorial is the VITAL study, which did not achieve the trial’s primary outcome of significantly reducing cardiovascular disease events, but did show that omega-3s were associated with a statistically significant 28% risk reduction of heart attack and 17% risk reduction in coronary heart disease.

One of the main concerns is how this study will be received by the public, and the impact it will have on supplements. It has already been picked up by The New York Times, which quotes the lead author of the study, Safi U. Khan, MD, as saying, ““People who are taking these supplements for the sake of improving their cardiovascular health are wasting their money.”

“The study, editorial and video are wrongheaded in their conclusions and amount to malpractice on the public and the research community by discounting previous health and nutrition research that form the basis of current guidelines and recommendations,” stated Mister. “Taking dietary supplements and practicing healthy dietary patterns are essential ways for consumers to assure they are getting the recommended levels of nutrients essential for overall health and wellness. Cardiovascular disease, in particular, has many contributing causes, and consumers must practice healthy habits to maintain cardiovascular health. CRN encourages consumers to talk to their healthcare practitioners about their dietary supplement use, diet and regular physical activity levels.”

Mister also noted that consumers don't turn to supplement to reduce their risk of death or to prevent heart disease, but to fill nutrient gaps in their diet.