Taking vitamin and mineral supplements does not help ward off heart disease, stroke or early death, according to a major review article published this week in the Journal of the American College of Cardiology.
The exception might be folic acid, which is a synthetic form of folate (vitamin B-9). The review found low- to moderate-quality evidence that folic acid reduces the risk for heart disease and stroke.
“We were surprised to find so few positive effects of the most common supplements that people consume,” said David Jenkins, the review’s lead author and a professor of nutrition sciences and medicine at the University of Toronto, in a released statement. “Our review found that if you want to take multivitamins, vitamin D, calcium or vitamin C, it does no harm — but there is no apparent advantage either.”
The review’s findings are just the latest in a long string of evidence that has undercut the longstanding idea that vitamin and mineral supplements act as a form of “insurance” against chronic disease.
The findings are also in line with the current (2014) recommendations from the United States Preventive Services Task Forces (USPSTF), which says there is no good evidence that vitamin and mineral supplements protect against either heart disease or cancer.
Almost 200 studies
For the review, Jenkins and his co-authors analyzed the results of 179 randomized controlled trials (considered the gold standard for medical studies) on the effect of vitamin and mineral supplement use on cardiovascular disease, which includes heart disease, stroke and other conditions affecting the heart and blood vessels. Some of the studies also examined the supplements’ effects on death from all causes. The studies were published from January 2012 through October 2017 — both before and after the USPSTF experts reviewed the evidence for its current guidelines
The analysis revealed that the four most commonly used supplements —multivitamins, vitamin C, vitamin D and calcium — were not associated with a reduced risk of developing cardiovascular disease or of dying early from any cause.
None of those supplements was associated with harming health, either.
That was not true of niacin (vitamin B3) or antioxidant supplements, which were both linked to an increased risk of early death. (The antioxidant supplements reviewed were ones containing two or more of the following: vitamin A, vitamin C, vitamin E, beta-carotene, selenium or zinc.)
Taking folic acid, however, was found to be associated with a reduction in the risk of cardiovascular disease in general (by 17 percent) and stroke in particular (by 20 percent).
Those findings are based primarily on a single large Chinese study, however.
“Folic acid administration and the reduction of cardiovascular disease through stroke seen in the Chinese [clinical] trial provides the only example of cardiovascular disease risk reduction by supplement use in the period following the Preventive Services Task Recommendation,” said Jenkins. “Whether these data are sufficient to change clinical practice in areas of the world where folic acid food fortification is already in place is still a matter for discussion.”
Best bet: eat plenty of fruits and veggies
As Jenkins and his co-authors point out in their paper, their review comes with several caveats. Most notably, they had little data to analyze for some of the supplements because very few clinical trials had looked into their effect on cardiovascular disease. More studies — with greater numbers of people — might reveal different results.
Still, the review reinforces the conclusion that the USPSTF and other independent researchers have reached in recent years: There is no good evidence to support the commonly held belief that everybody — not just people with specific vitamin or mineral deficiencies — needs to take supplements because the modern Western diet is low in nutrients.
Furthermore, supplements are not always benign. Some may do harm. Other research has linked vitamin E supplements to an increased risk of prostate cancer, for example.
“People should be conscious of the supplements they’re taking and ensure they’re applicable to the specific vitamin or mineral deficiencies they have been advised of by their healthcare provider,” said Jenkins.
“In the absence of significant positive data — apart from folic acid’s potential reduction in the risk of stroke and heart diseases — it’s most beneficial to rely on a healthy diet to get your fill of vitamins and mineral,” he adds. “So far, no research on supplements has shown us anything better than healthy servings of less processed plant foods, including vegetables, fruits and nuts.”
FMI: The review can be read in full on the website for the Journal of the American College of Cardiology.