The Chinese researchers studied more than 20,000 adults with high blood pressure but without any history of stroke.

Eligible participants, men and women, aged 45 to 75 years old had hypertension, in 140 mm Hg or diastolic blood pressure of 90 mm Hg or higher at both the screening and recruitment visits or were taking an antihypertensive medication.

The major exclusion criteria included history of physician-diagnosed stroke, myocardial infarction (MI), heart failure, coronary revascularization, or congenital heart disease.

Half of them were given a folic acid supplement, such as vitamin B along with enalapril, a medication designed to lower blood pressure.

The other group was given only enalapril without the folic acid. Those who took the folic acid supplement were less likely to have a stroke than those who didn’t take any, they found.

Folate is available in high dosages from leafy vegetables, grains, pastas, lentils, beans, asparagus, spinach, broccoli, peas, and citrus fruits and those who are not exposed to enough folate, such as those on gluten-free diets and Americans in the southwest who use corn flour instead of grains, are at risk.

High blood pressure or hypertension can develop without any symptoms, but can have life-threatening consequences if not treated. Over time, the force of the blood flow continues to push too high against the artery walls and the tissue that stretches walls damages them in turn.

“Fruits and vegetables are important sources of folate in the diet, and they also bring lots of other benefits, such as potassium and phytonutrients, that also help lower cardiovascular disease,” says Walter Willett, professor of epidemiology and nutrition from Harvard T.H. Chan School of Public Health.

The new study’s findings may encourage incorporating vitamin B supplements or a diet with folic acid-rich foods to help the millions who have high blood pressure.