A colorful graphic representing vitamins, chickpeas, and spinach.

If you’re one of the almost 1 in 3 Americans who has high blood pressure, you may have heard that taking folic acid will help prevent heart disease. 

A Chinese study published today in the Journal of the American College of Cardiology found that a certain subgroup of people with high blood pressure may indeed benefit from taking this supplement.

The new research, however, may be most relevant for people who live in countries such as China, where foods are not fortified with folic acid. In the U.S., the Food and Drug Administration has required many grain-based products, such as cereal, to be fortified with folic acid since 1998.

More on Heart Health

Earlier research found that people who consumed more folate—the natural form of this B vitamin, found in foods—had fewer strokes and heart attacks. But recent studies have been mixed about whether or not taking folic acid, which is the synthetic form of the vitamin, yields the same benefits.

The new research “helps us zero in on a small, at-risk group here in the United States who may benefit from additional supplementation," says Clyde Yancy, M.D., chief of cardiology at the Northwestern University Feinberg School of Medicine in Chicago.

But the study's findings don't mean you should start taking folic acid supplements—even if you do have high blood pressure. Here’s what you need to know.

What the Research Found

Researchers looked at more than 10,000 people in China, all of whom had a history of high blood pressure but had not yet suffered a stroke or heart attack.

They were given a daily dose of the blood-pressure medication enalapril (Vasotec and generic), with about half also receiving 800 mcg of folic acid every day.

Four years later, there were fewer strokes in the group taking folic acid along with enalapril.

But the most dramatic results were seen among patients in a particular subgroup: those who had a low platelet count and high levels of homocysteine, an amino acid produced naturally by the body. (High homocysteine levels can be caused by B-vitamin deficiencies as well as medical conditions such as kidney disease.) 

Those findings makes sense: High homocysteine levels have been linked to heart disease, since this substance damages the artery wall, says Seemant Chaturvedi, M.D., a professor of clinical neurology at the University of Miami. And folate—itself a B vitamin—has been shown to break down homocysteine, whether you get it through food or through a supplement.

But while this new research is interesting, it doesn't apply to most people with high blood pressure, who don't necessarily have a low platelet count and high levels of homocysteine as well, and it doesn’t apply to most people in the U.S.

Folate deficiency in the U.S. is relatively rare. That fact could help explain why Chinese participants in previous studies have seen benefits while other studies done in the U.S. haven’t had the same results, says Ken Uchino, M.D., a stroke neurologist at the Cleveland Clinic.  

Why You Need Folate

Most people won’t benefit from folic acid supplements. (All supplements have risks, because they are not regulated like medications.) Excess folic acid can also mask B12 deficiency in blood tests and even cause numbness and tingling in people with a common gene variant.

But it’s still essential to make sure you get enough folate in your diet because it’s crucial to heart health, stresses Brian Silver, M.D., vice chair of neurology at the University of Massachusetts.

The National Institutes of Health recommends that most adults get at least 400 micrograms a day. (Pregnant and breastfeeding women need 600.)

Folate is found mainly in fruits and vegetables. Spinach, asparagus, and brussels sprouts are all good sources, along with beans (such as chickpeas), citrus fruit, and whole grains. A fortified breakfast cereal usually contains around 100 mcg of folic acid, for example, and a half-cup of cooked spinach contains about 130 of folate.

While most people can easily get enough folate through food, there are people in certain subgroups in the U.S. who may be at risk for deficiency. They include those who have a disease that affects absorption in their GI tract, such as celiac disease or an inflammatory bowel disease like Crohn’s. Certain medications, like methotrexate (Rheumatrex, Trexall and generic), which is used to treat autoimmune disorders, or seizure drugs such as phenytoin (Dilantin and generic) can also affect how the body absorbs folate.

In these cases, you should talk to your doctor about getting your blood-folate levels checked, and if they are low, consider a supplement, says Nieca Goldberg, M.D., medical director of NYU Langone's Joan H. Tisch Center for Women's Health.

How to Guard Your Heart

While folate is an important piece of the puzzle when it comes to solving heart disease and strokes, “there’s no magic bullet—it comes down to eating a heart healthy diet,” says Silver.

Fruits and vegetables, for example, aren’t just rich in folate, they’re full of many other vitamins and minerals such as potassium that may reduce the risk of heart disease. A recent Swedish study published in the journal Stroke looked at more 70,000 men and women for over a decade and concluded that those who followed the DASH diet—a low-sodium eating plan that's packed with fruits, vegetables, and low-fat dairy—had a 14 percent lower risk of stroke.

Overall lifestyle is key, too, adds Silver. In fact, 10 risk factors—all of which you can work on lowering—are responsible for about 90 percent of strokes, according to a study published in 2016 in The Lancet.

Besides eating a heart healthy diet and exercising regularly, it’s important to make sure that you get your blood pressure under control (to below 130/80) and manage other conditions such as high cholesterol, type 2 diabetes, and atrial fibrillation (A-fib), a quivering or irregular heartbeat that affects 5 percent of people older than 65, says Chaturvedi.