MONDAY, July 8, 2019 (HealthDay News) -- If you take supplements hoping to ward off a heart attack or stroke, yet another study suggests you could find better uses for your hard-earned dollars.
A review of 277 published studies found that most supplements won't protect you from cardiovascular disease or early death.
"The study carries a simple message -- do not waste your money," said lead researcher Dr. Safi Khan.
"Americans spend billions of dollars on supplements and vitamins, but this study provides evidence that few of these supplements have a significant effect on mortality or cardiovascular outcomes," said Khan, an assistant professor of medicine at West Virginia University.
If not supplements, what will help your heart?
"Instead of nutritional supplements, behavioral modifications -- such as good nutrition from healthy food sources, exercise and smoking cessation -- remain the main factors for improving cardiovascular health," he said.
Khan's team looked at 16 nutritional supplements and eight diets in studies that included nearly 1 million people in all.
The investigators did find some evidence that a low-salt diet reduced premature death among those with normal blood pressure, and that omega-3 fatty acids in food protected against heart attack and heart disease. Also, folic acid was somewhat protective against stroke, they reported.
However, calcium plus vitamin D, which many people take for stronger bones, increased the risk for stroke, the researchers found.
Multivitamins and other supplements -- including selenium, vitamin A, vitamin B6, vitamin C, vitamin E, vitamin D alone, calcium alone, folic acid and iron -- did not have a significant effect on death or heart disease, according to the study.
Certain dietary interventions didn't seem to make a big difference, either. The analysis found no proof that switching to the Mediterranean diet, reducing fats or saturated fats, or increasing fish oil supplements would keep heart disease or death from the door, the researchers said. (The Mediterranean diet centers around vegetables, fruits, nuts, whole grains and beans.)
Despite the lack of evidence, one out of two Americans takes supplements hoping to improve their health, the researchers said.
Dr. Eric Topol, a professor of molecular medicine at Scripps Research in La Jolla, Calif., said, "Forget about supplements -- you don't improve heart outcomes at all."
Topol, co-author of an accompanying journal editorial, added that taking supplements could cause unwanted side effects.
Supplements aren't harmless, he said. "They have all sorts of impurities, and they're not regulated. We shouldn't just take for granted that they're inert," he noted.
Topol also said the notion that salt causes high blood pressure has no evidence to back it up. "The salt question is still shaky," he said. "The data are not clear."
In addition, what keeps one person healthy might not work for someone else, Topol said.
"The idea that there is a magic diet for all people -- we have to get over that. It's never going to be the case, because we're all so unique," Topol explained.
This study follows two other papers that also found no benefit from supplements in reducing chances of heart disease or death.
One study was published last July in the journal Circulation and the other came out in April in the Annals of Internal Medicine.
Dr. Gregg Fonarow, a professor of cardiology at the University of California, Los Angeles, said the findings are to be expected.
"As surprising as these findings may be, there is no high-quality evidence to support the use of multivitamins, individual vitamins, mineral supplements or dietary interventions, including reduced dietary fat, reduced saturated fats, the Mediterranean diet or fish oil supplements for cardiovascular event reduction," he said.
Fortunately, lowering cholesterol and blood pressure, and quitting smoking have been shown to reduce heart attacks, strokes and heart disease, Fonarow said.
A leading trade group for the dietary supplement industry objected to the study findings.
"This study is a coordinated, all-out assault on nutrition, and the critical role it plays in maintaining health and reducing the risk of chronic disease," said Steve Mister, president and CEO of the Council for Responsible Nutrition, in Washington, D.C.
The study authors ignore the "proper role" of supplements for overall health and wellness, Mister said in a statement released Monday. Consumers should talk to their health care practitioners about their dietary supplement use, he advised.
The report was published online July 8 in the Annals of Internal Medicine.
For more on supplements and heart health, head to the American Heart Association.