Most of the people use supplements and vitamins to protect their health. But a new study suggests that supplements and dietary interventions provide little to no protection against cardiovascular disease or death.
The study, published in the “Annals of Internal Medicine” reviewed data from hundreds of clinical trials which involved nearly a million people. The research found that only a few of sixteen popular supplements and just one of the eight diets evaluated had any noticeable effect on cardiovascular outcomes.
The study examined that omega-3 fatty acid which is commonly found in fish oil reduced the risk of heart attacks and coronary diseases and the folic acid reduced the risk of stroke. But the evidence was fairly weak. It showed that taking calcium with vitamin D increased the risk of stroke, possibly because it increases blood clotting and hardening of the arteries.
In their research, the first author Dr Safi Khan from West Virginia University and his team included 24 different interventions comprising 277 randomized trials. The researchers also found that taking multivitamins, selenium, vitamin A, vitamin B-6, vitamin C, vitamin D, vitamin E, calcium, folic acid, and the iron did not significantly protect against cardiovascular problems and early death. They also noted that following a Mediterranean diet, reducing saturated fat intake, modifying fat intake, reducing dietary fat intake, and increasing the quantity of dietary omega-3 and omega-6 were not beneficial. But in the research paper, the researchers point out that, “these findings are limited by the suboptimal quality of the evidence.” They are referring to the fact that, due to the different methodologies of the studies that they assessed, they “could not analyze interventions according to important subgroups, such as sex, body mass index [BMI], lipid values, blood pressure thresholds, diabetes, and history of cardiovascular disease.”
The authors, in conclusion, also suggest that this study can help those who create professional cardiovascular and dietary guidelines modify their recommendations, provide the evidence base for clinicians to discuss dietary supplements with their patients, and guide new studies to fulfil the evidence gap.

Source: 1. Khan SU, Khan MU, Riaz H, et al. Effects of nutritional supplements and dietary interventions on cardiovascular outcomes. Ann Intern Med. 2019;171:190-198.
2. Medical News Today
3. The New York Times
4. CNN