A new study published in Annals of Internal Medicine suggests that nutritional supplements and dietary interventions have little to no effect on cardiovascular health. Experts are already pointing out that the study ignores all observational trials, which serve as the major basis for dietary guidelines—and the study itself notes that the evidence the researchers used was suboptimal.
The researchers used nine systemic reviews and four randomized controlled trials, encompassing a total of 277 trials, 24 interventions, and 992,129 participants. The researchers found, according to the study’s abstract, moderate-certainty evidence that reduced salt intake decreased the risk for all-cause mortality in participants with good cardiovascular health and reduced risk of cardiovascular mortality in hypertensive participants. Researchers found low-certainty evidence that omega-3s were associated with reduced risk for myocardial infarction and coronary heart disease. Folic acid was associated with lower risk of stroke—again at a low certainty—whereas calcium plus vitamin D increased the risk for stroke.
Other nutritional supplements—vitamin B6, vitamin A, multivitamins, antioxidants, and dietary interventions such as reduced fat intake, “had no significant effect on mortality or cardiovascular disease outcomes,” according to the abstract.
The study’s conclusions were: “Reduced salt intake, omega-3s, and folate supplementation could reduce risk for some cardiovascular outcomes in adults. Combined calcium plus vitamin D might increase risk for stroke.”
And the limitations? “Suboptimal quality and certainty of evidence.”
The Council for Responsible Nutrition (CRN) released a media statement regarding the study. Steve Mister, president and CEO, said in the release: “This study is a coordinated, all-out assault on nutrition, and the critical role it plays in maintaining health and reducing the risk of chronic disease. It recklessly disregards decades of comprehensive, carefully developed, and well-conducted nutrition research on the benefits of both supplemental nutrients and healthy dietary patterns. It maligns not only dietary supplements, but also well-established dietary patterns, such as the Mediterranean Diet and the Low-Sodium Diet. It lacks insight from any nutrition-based medical professional or expert with knowledge or appreciation of nutrition research.”
Mister noted that the exclusion of observational trials is “a major limitation, as epidemiological data are critical and serve as the basis of many recommendations made in the Dietary Guidelines for Americans.” He adds that the study ignores both the proper role and the in-practice usage of supplements: intended to fill nutrient gaps, “Consumers turn to many of these dietary supplements not to reduce their risk of death or prevent heart disease, but rather to fill nutrient gaps in their diets and to maintain health in other ways—e.g., folic acid to prevent birth defects, calcium and vitamin D to prevent falls and fractures, iron to address anemia.”
Mister concluded by saying: “The study and accompanying 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. 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.”