Nov. 5, 2012 (Los Angeles) -- Don't count on a vitamin a day to protect you from heart disease. A large, well-designed study shows that men who took daily multivitamins for years did not lower the risk of heart attack, stroke, or death from heart disease.
The study followed nearly 15,000 middle-aged and older men for about 11 years. It is not yet clear if the findings would apply to younger men or women. But a previous study of more than 160,000 women also found that multivitamins did not affect the chance of having heart disease or stroke.
Previous findings from the same study showed that daily multivitamin use reduced the risk of cancer by a modest 8%.
"The main reason to take a daily multivitamin ... remains to prevent vitamin and mineral deficiency,'' says researcher Howard Sesso, ScD, MPH, an epidemiologist at Brigham and Women's Hospital and Harvard Medical School.
"There is no reason to recommend multivitamins for cardiovascular disease. The decision to take a multivitamin should consider its beneficial effects on cancer and other important [health conditions still being] studied," Sesso said at a news briefing at the annual meeting of the American Heart Association here.
Sesso and heart doctors not involved with the study repeatedly said that they fear taking multivitamins lulls people into a false sense of security, distracting them from following proven steps to prevent heart disease.
"The opinion that people take a multivitamin in lieu of other healthy habits that can lower heart disease risk is a recurring statement that lacks an evidentiary basis," the CRN says in a statement.
The findings are also published today in the Journal of the American Medical Association.
Vitamin Use Soars
Previous studies looking at the effect of multivitamin use on heart disease have had mixed results. And large trials of high doses of individual vitamins, such as beta-carotene and vitamin E, have generally shown they do more harm than good.
Despite the lack of solid evidence showing that vitamins and dietary supplements protect against heart disease and many other health conditions, more than half of American adults take at least one supplement, and about 10% take more than five, according to Eva Lonn, MD, of McMaster University in Hamilton, Ontario.
Given their widespread use, their impact on heart disease (the nation's No. 1 killer) is of great importance, says Lonn, who wrote an editorial accompanying the study. In the U.S., heart disease accounted for 1 in 3 deaths in 2008.
The new study is the first large-scale study pitting multivitamins against a placebo in heart disease prevention, Sesso says. Studies like this -- which compare a treatment to placebo or to standard medication, and then follow people over time to see how many in each group develop a disease -- are the gold standard.
Vitamins and Heart Disease Risk: Details
In the study, about half of the 15,000 men took a daily multivitamin, Centrum Silver. The other half took placebo. When they started the study, they were 50 or older; their average age was 64.
At the start, 754 men had a history of heart disease or stroke.
In the vitamin group, 876 of 7,317 men had a nonfatal heart attack or stroke, or died from cardiovascular disease. In the placebo group, 856 of 7,324 men did. That made their rates of these major events virtually identical.
There was also no effect of multivitamin use on most individual heart conditions. The rates of any heart attack (fatal or nonfatal), any stroke, and death due to stroke were the same in both groups. There were slightly fewer deaths in the vitamin group than in the placebo group, but the difference was so small it could have been due to chance.
The effect of taking daily multivitamin on major heart conditions did not differ between men with or without a history of heart disease.
The vitamin generally appeared well-tolerated, Sesso says. Men in the vitamin group were slightly more likely to develop skin rashes.
Sesso notes that the people in the study represented "a well-nourished population who already has adequate or optimum intake levels of nutrients, for whom supplementation may offer no additional benefits." Future research is needed to look at the impact of vitamins on people who don’t eat as well, he says.
The researchers received research funding from the National Institutes of Health. They received vitamins or support from BASF Corporation, Pfizer, and DSM Nutritional Products Inc.
Vitamins and Heart Disease: Perspectives
Doctors say the findings reinforce a message they try to impress upon their patients: Vitamins cannot replace a healthy lifestyle and a good diet.
"Many people with heart disease risk factors or [a history of heart disease] lead [inactive] 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 this approach will prevent a future [heart attack] or stroke.
"This distraction from cardiovascular disease prevention is the main hazard of using vitamins and other unproven supplements," Lonn says.
American Heart Association spokesman Elliott Antman, MD, of Harvard Medical School, says, "Thinking of multivitamins as a quick fix can have dangerous consequences. You should not assume that by taking a vitamin, you can forgo the things that work." Antman was not involved with the research.
Duffy MacKay, ND, vice president of scientific and regulatory affairs at the CRN trade group, says people who use vitamins are the very people who are most likely to have a healthy lifestyle.
"Government and other studies show that supplement users are more likely to be leaner and more physically active than non-supplement users. Our own research shows similar kinds of results, with supplement users being more likely than non-users to try to eat a healthy diet, engage in regular physical activity, and see a doctor regularly. It’s the whole lifestyle package, including consistent, long-term use of vitamins, that helps lead to good health," he says.