A daily multivitamin doesn’t protect against heart attack, stroke or heart-related death, according to a new large-scale study among men.
It’s the first large trial in which men were randomly assigned to either take a multivitamin or a placebo and then followed to see if the vitamins had any effect on their rate of heart disease. But after 10 years, researchers found no difference in heart-disease rates between the two groups.
Previous studies on the topic have been both conflicting and confusing, with some showing a higher risk of early death, including from cancer, among those taking multivitamins or supplements, and others showing a benefit in avoiding death from cancer among men. But most of those trials followed people who chose to take multivitamins and compared them with people who did not, setting up a potential bias since it’s hard to determine if multivitamin users are more health conscious and therefore do other things to protect their health, including taking a multivitamin, that may account for their lower risk of heart problems.
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For this latest study, published in the Journal of the American Medical Association, researchers led by Howard Sesso of the Brigham and Women’s Hospital and Harvard Medical School studied a group of almost 15,000 male physicians age 50 or older in the Physicians’ Health Study, a long-term trial begun in 1997 that analyzes a number of different health outcomes. The researchers randomly selected half of the physicians to take a daily multivitamin while the other half took a placebo. None of the study participants knew whether they were receiving the real vitamin supplements or an inactive stand-in.
Over 11 years of follow up, the physician participants recorded 652 heart attacks and 643 strokes, and 829 men died from a cardiovascular-related cause. But there was no significant difference in the rates of these events between the men who took the multivitamins and the men who did not. The multivitamins didn’t seem to make any difference at all.
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More than half of American adults take some form of dietary supplement, and roughly 40% take a multivitamin, according to an editorial accompanying the new research. Vitamin supplements are supposed to guard against nutritional deficiencies. But the people most likely to take them every day — not unlike the doctors enrolled in this new study — tend to be wealthier, healthier and more educated than average. These people are the least likely to be poorly nourished or have dietary deficiencies that vitamins would correct. So as the study results show, they may also be the least likely to benefit from supplements.
However, Sesso and his colleagues say their study looks only at the effects of multivitamins on heart-disease outcomes. It does not consider cancers, osteoporosis or any other conditions, some of which could be affected by the use of nutritional supplements. And the trial did not find any evidence that multivitamins are harmful to heart health.
Still, some experts hope that the results lead the public, and their doctors, to question multivitamins and what role they play in their health. Many people, for example, overestimate the benefits of nutritional supplements like multivitamins and rely on them as cure-alls or worthy substitutes for a healthy diet. According to Dr. Eva Lonn, a cardiology professor at McMaster University in Ontario, Canada, who wrote the editorial:
[M]any people with heart disease risk factors or previous [cardiovascular disease (CVD)] events lead sedentary lifestyles, eat processed or fast foods, continue to smoke, and stop taking lifesaving prescribed medications, but purchase and regularly use vitamins and other dietary supplements, in the hope that this approach will prevent a future [heart attack] or stroke. This distraction from effective CVD prevention is the main hazard of using vitamins and other unproven supplements. The message needs to remain simple and focused: CVD is largely preventable, and this can be achieved by eating healthy foods, exercising regularly, avoiding tobacco products, and, for those with high risk factor levels or previous CVD events, taking proven, safe, and effective medications.
Supplements are often marketed to look like over-the-counter medications. But they are not regulated like medications. While drugs are rigorously tested before they can be sold in stores, supplements can hint at health benefits without strong evidence. Supplement packaging will usually carry a disclaimer like: “These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure or prevent any disease.” But that may not be enough to remind people that they aren’t designed to replace a healthy lifestyle. As tempting as they are, multivitamins may not be the panacea that many think they are; and, as the latest research shows, they can’t replace a diet low in salt and fat and regular exercise for keeping the heart healthy.