If you’ve been warned by your doctor about borderline high blood pressure, you may want to give yoga a try. According to a small new study, people with prehypertension who practiced yoga for an hour a day for three months lowered both their average diastolic and arterial pressure.

The study was presented at the Cardiological Society of India’s annual conference. (It has not yet been published in a peer-reviewed medical journal.) The study authors say the results are promising, and that adopting a daily yoga habit could potentially protect those with prehypertension from the damaging effects of high blood pressure.

"Both prehypertension and high blood pressure increase the risk of heart attack, stroke and heart failure,” said lead author Ashutosh Angrish, MD, a cardiologist at Sir Gangaram Hospital in Delhi, India.

Prehypertension is defined as a systolic reading (the first number in a blood pressure reading) of 120 to 139 mm Hg or a diastolic reading (the second number) of 80 to 89 mm Hg, while full-blown hypertension requires a systolic reading greater than 140 mm Hg or diastolic reading greater than 90 mm Hg. People who have prehypertension will likely develop hypertension "unless they improve their lifestyle," Dr. Angrish says. 

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Dr. Angrish wanted to investigate the impact of Hatha yoga—a traditional branch of yoga that combines stretching poses, controlled breathing, and meditation—on people who’d been diagnosed with prehypertension but were otherwise healthy. So he and his colleagues recruited 60 such patients, average age 54, and prescribed all of them lifestyle strategies for lowering blood pressure. These included moderate aerobic exercise, a healthy diet, and quitting smoking. 

Half of those patients also received a month of daily yoga lessons, taught by an instructor. After the first month, this group was told to practice on their own for an hour a day.

At the beginning and end of the three-month study period, participants had their blood pressure measured over a 24-hour period. During that time, there were no changes in the group that was assigned lifestyle changes only.

In the yoga group, however, both 24-hour diastolic blood pressure and nighttime diastolic blood pressure decreased by approximately 4.5 mmHg. Average arterial pressure decreased as well, by about 4.9 mmHg.

"Although the reduction in blood pressure was modest, it could be clinically very meaningful,” Dr. Angrish said in a press release. Even a 2 mm Hg decrease in diastolic blood pressure has the potential to decrease the risk of coronary heart disease by 6%, and the risk of stroke by 15%, he added.

The reasons why yoga has these effects aren't clear from this research, but other studies have suggested that yoga may calm the sympathetic nervous system, which plays a role in regulating blood pressure.

“The findings suggest that a combination of all three components of yoga (asanas, pranayama, and meditation) is helpful, but our study is unable to pinpoint their individual contribution," said Dr. Angrish.

Shirish Hiremath, MD, president-elect of the Cardiological Society of India, said in a press release that yoga—a traditional part of Indian culture—has shown clear benefit in cases of prehypertension. Plus, he added, it’s easy to learn and inexpensive to practice.

“Yoga can turn out to be just the correct answer for people at risk,” he said, noting that a large number of young Indians are affected by hypertension. (A 2014 review found that 29% of India’s population, or one in three people, has high blood pressure; current estimates for the United States are similar.)

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Roberto Ferrari, MD, course director of the European Society of Cardiology program in India, agreed that yoga can be an important part of a heart-healthy strategy—but stresses that it's just one component. “Cardiovascular disease can be prevented by adopting a healthy lifestyle and controlling blood pressure and cholesterol,” he said. “Exercise, including yoga, a good quality diet, and not smoking are all steps in the right direction.”

Dr. Angrish’s findings should be considered preliminary. Even so, he said, there’s little reason not to advise people worried about their blood pressure (and who are otherwise healthy) to start a daily yoga practice. “It may prevent the development of hypertension,” he said, “and in addition give a sense of well-being.”