If you like the idea of warding off disease by taking vitamin supplements, you’ve probably been disheartened by the research in this area over the last few years. A new study won’t help. It finds that the vast majority of the vitamins and minerals analyzed didn’t have any measurable benefit, at least when it came to the outcomes studied here—cardiovascular disease, stroke, and early death. This is not to say that certain supplements aren’t necessary for some people, but taking vitamins as a general preventative measure just doesn’t have a lot of evidence behind it.
The authors, publishing in the Journal of the American College of Cardiology, looked over data from past studies that had randomized participants to receive A, B1, B2, B3 (niacin), B6, B9 (folic acid), C, D, E, beta-carotene, calcium, iron, zinc, magnesium, selenium. Others used multivitamin supplements or antioxidant supplements, which was defined as containing two or more of vitamins A, C, E, beta-carotene, selenium, and zinc. The team looked at various long-term health outcomes including cardiovascular disease, stroke, and death from any cause.
The study was carried out by researchers at a number of universities, including the University of Toronto and the Harvard School of Public Health.
It turned out that multivitamins, vitamin D, calcium, and vitamin C—the most common supplements these days—conferred no benefit in preventing heart disease, heart attack, stroke or premature death. But they didn’t increase the risk of these events either.
“We were surprised to find so few positive effects of the most common supplements that people consume,” said study author David Jenkins in a statement. “Our review found that if you want to use multivitamins, vitamin D, calcium or vitamin C, it does no harm — but there is no apparent advantage either.”
One exception was folate and other B-vitamins: there was low- and moderate quality evidence that folate or folic acid (B9) reduced the risk for heart disease. There was also some evidence that folate and other B vitamins reduced the risk of stroke.
On the flipside, the results suggested that niacin (B3) and antioxidants seemed to raise the risk of death from any cause. “These findings suggest that 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.
The study is generally in line with others in recent years, finding that vitamin supplements are not all they’re cracked up to be. In some instances, they may even present some risk. “In the absence of significant positive data — apart from folic acid’s potential reduction in the risk of stroke and heart disease — it’s most beneficial to rely on a healthy diet to get your fill of vitamins and minerals,” said Jenkins. “So far, no research on supplements has shown us anything better than healthy servings of less processed plant foods including vegetables, fruits and nuts.”
The authors point out that over 50% of the population in the U.S. are estimated to take supplements of some sort. Multivitamins are thought to be taken by over 30% of the population, vitamin D by 19%, calcium by 14%, and vitamin C by 12%. The vitamin industry is of course a multi-billion dollar industry.
Though vitamins have been life-saving in certain severe cases historically (e.g., scurvy), experts have moved away from recommending them for the prevention of chronic illness. As the authors point out, the U.S. Preventive Services Task Force wrote in their guidelines that they believe “that the current evidence is insufficient to assess the balance of benefits and harms of single or paired nutrient supplements (except for b-carotene and vitamin E) [that were recommended against] for the prevention of cardiovascular disease and cancer.” (Beta-carotene, or vitamin A, supplements have been linked to cancer in smokers; vitamin E has been linked to prostate cancer.)
Again, the new study echoes the general consensus in the last several years. People who have confirmed deficiencies or are borderline deficient should of course take supplements at their doctor’s recommendation. But in terms of prevention of chronic illness, there’s not much to suggest vitamins supplements do much good. Of course, ramping up on vitamin-rich foods is another story: That has certainly been shown to reduce disease risk of many descriptions.