With newer research, the evidence continued to show no cardiovascular benefits to dietary supplements except B vitamins, researchers reported.
No cardiovascular or mortality effects were seen with multivitamins, vitamin D, calcium, or vitamin C in a meta-analysis incorporating 156 randomized controlled trials and meta-analyses, according to a group led by David Jenkins, MD, PhD, of the University of Toronto in Ontario.
Only moderate-quality evidence was available associating folic acid (vitamin B9; RR 0.79, 95% CI 0.69-0.92) and B vitamins (RR 0.90, 95% CI 0.81-1.00) with reduced stroke risk, Jenkins and colleagues reported in the Journal of the American College of Cardiology (JACC).
“In the last 2 years, there have been no trials of sufficient size and consistency to alter the advice previously given by the USPSTF [U.S. Preventive Services Task Force] 7 years ago that identified a general lack of effect of vitamins and minerals in altering the risk of CVD [cardiovascular disease] or total mortality, with the exception of folic acid and the B vitamins that reduce stroke,” the authors noted.
Niacin (vitamin B3) was tied to increased all-cause mortality (RR 1.10, 95% CI 1.00-1.20) when taken with background statins, the researchers warned.
They noted the addition of 35 papers to the dataset since their last literature review of diet supplements in 2018.
With newer data, the verdict is in for vitamin D: these supplements “do not benefit cardiovascular health in the general population and therefore should not be taken for this purpose,” said another group, led by Erin Michos, MD, MHS, of Johns Hopkins School of Medicine in Baltimore.
“The pendulum has shifted, and the hype for vitamin D supplements as a panacea for multiple diseases, including CVD, is over. Even the benefits of supplemental vitamin D on bone health appear overstated for the general population,” Michos and co-authors wrote.
They undertook a separate literature review of dietary supplementation data, also published in JACC, finding calcium to be potentially harmful while also arriving at the conclusion that vitamin D does not benefit cardiovascular health.
These two supplements, often taken together for bone health, had no heart benefits when looking at the totality of observational and randomized studies such as ViDA and the more definitive VITAL trial, the team said.
Yet whether vitamin D supplementation helps in cancer, COVID-19, or people who are vitamin D deficient remains unknown, Michos’ team acknowledged.
No trial of calcium supplementation has been a designated cardiovascular outcome trial.
Nevertheless, since some data suggested cardiovascular harm with calcium supplements, the group suggested they “be used cautiously, striving for recommended intake of calcium predominantly from food sources.”
Jenkins and colleagues also stressed that people get their essential nutrients from diet, stating: “In the absence of very clear micronutrient health benefits and with concerns that excess consumption of certain micronutrients may have undesirable consequences, it appears that more certain CVD gains can be achieved by dietary change that follows the move to more plant-based diets, as advised now internationally.”
The meta-analysis was supported by the Canada Research Chair Endowment, Loblaw Cos., and the Canadian Institutes for Health Research.
Jenkins and co-authors listed numerous ties to industry, including research grants from food companies.
Michos and co-authors reported that they have no relationships relevant to the contents of their review to disclose.