Walk into any pharmacy or health-food store and you’ll see shelves of dietary supplements that promise to help your heart, such as omega-3, coenzyme Q10 (CoQ10), and red yeast rice.

Proponents claim that these products can lower blood pressure or cholesterol, stave off heart disease, and prevent heart attacks. If you’re concerned about your heart health, should you be taking them?

What the Science Says

Omega-3 (fish oil). It’s well-established that regularly consuming foods that contain omega-3 fatty acids (see “Ticker-Friendly Foods,” below) is a bonus for heart health. But the evidence on supplements has been scant.

However, a recent scientific advisory report from the American Heart Association, published in the journal Circulation, concluded that people who have already had a heart attack or been diagnosed with heart failure may benefit from a daily 1,000-mg fish-oil supplement. For that group only, according to the AHA, this practice could reduce the risk of dying from heart disease by 10 percent.

“The benefits shown in recent studies have been modest, but I think taking them is still reasonable,” says JoAnn Manson, M.D., chief of the division of preventive medicine at Brigham and Women’s Hospital in Boston.

More on Heart Health

CoQ10. Supplements of this compound, which is produced by the body and found in some foods, have been promoted for the management of heart failure and alleviating muscle aches associated with cholesterol-lowering statin medications.

But conclusive evidence of its effectiveness is lacking. A 2014 review of seven small clinical trials found “no convincing evidence to support or refute” CoQ10’s use for heart failure. Another analysis found no strong evidence it reduces statin-induced muscle pain.

Red yeast rice. Red yeast rice—which is made by culturing rice with yeast—is claimed to lower LDL “bad” cholesterol. However, there is little evidence to support its use—or its safety. In fact, red yeast rice is one of 15 supplement ingredients that Consumer Reports recommends consumers always avoid.

Cause for Caution

With over-the-counter dietary supplements, you don’t always know what you’re getting.

“There’s a lack of regulation, which means the content, identity, and purity of the product is not guaranteed,” says Consumer Reports’ chief medical adviser, Marvin M. Lipman, M.D.

Manson agrees. “There are some high-quality supplements, but it’s very much buyer beware,” she says.

There’s also a risk that some supplements may include unwanted ingredients, interact with medications you take, or cause side effects.

For example, red yeast rice supplements can contain a chemical that’s been linked to kidney damage. It can also magnify the effects of statin drugs. CoQ10 may reduce the effectiveness of blood thinners, which are often used to help prevent heart attacks and strokes. Fish-oil supplements can lead to bleeding problems when combined with prescription blood thinners.

Be sure to discuss any supplements you’re taking or considering with your physician. “You can run into serious problems with drug interactions if your doctor doesn’t know,” Manson warns. 

Ticker-Friendly Foods

Fish-oil supplements have shown mixed results in research, and most experts agree that the best way to get the heart benefits of omega-3 fatty acids is through food.

“There’s no doubt that diet plays a big role in heart disease,” Lipman says. “And if you have a good diet, you don’t need supplements.”

So fill your plate wisely with plenty of foods rich in omega-3s, such as fatty fish like salmon, mackerel, and sardines; flaxseed; chia seeds; and spinach.

Editor's Note: This article also appeared in the Consumer Reports on Health newsletter.