For those who had doubts about trying to reap the medical benefits of what he dubbed “the relaxation response,’’ Dr. Herbert Benson had a ready answer.

“It’s not a drug, there are no side effects, and it’s cheap, other than your time,’’ he told the Globe in 2011. “It changes your genes’ activity. What could be more profound than that?’’

A pioneer in studying and extolling the medical benefits of meditation, Dr. Benson died of heart disease and kidney failure Thursday in Beth Israel Deaconess Medical Center. He was 86 and lived in Brookline.

His studies more than a half-century ago forged a path for meditation’s entry into the mainstream medical world, where now it is often incorporated into basic health regimens and specific treatments.

He launched the Mind/Body Medical Institute, which in 2006 became the Benson-Henry Institute for Mind Body Medicine at Massachusetts General Hospital with financial support from John Henry, the principal owner of the Boston Red Sox.

Dr. Benson, director emeritus of the institute, was “the primary founder of this area of medicine, mind/body medicine,’’ said Dr. Greg Fricchione, the current director.

“Herb Benson was one of the finest men I’ve ever met,’’ said Henry, who also owns the Boston Globe. “He gave me my first reasons for coming to Boston. He was the first doctor I knew of who was able to study and then translate the mind/body connection into specific results that significantly improved patient outcomes. Eventually he was able to do this for hospitals and patients around the world.’’

Early inspiration arrived in the 1960s. Dr. Benson was a young cardiologist teaching at Harvard Medical School and wondered why the blood pressure for many patients was higher when they visited a doctor’s office than when they took readings at home.

He speculated that their nervous anticipation of medical appointments might be the cause and, by extension, that stress elevated their blood pressure.

Dr. Benson initially studied the link during a research fellowship at the medical school, a fraught endeavor at that time. Some colleagues dismissed his theory as “bizarre,’’ he told the Globe in 2009. “It was a different world then,’’ he said, “a time when the phrase, ‘It’s all in your head,’ was a pejorative in medicine.’’

“It was not the thing to do if you wanted to fast-track your career to become a professor,’’ Fricchione said in an interview. “But he was undaunted because he saw something there. He was brave enough, and believe me it took courage in those days.’’

When Dr. Benson subsequently studied the physiological responses of those who practiced transcendental meditation, “the facts were incontrovertible,’’ he later wrote in one of his books.

“With meditation alone,’’ he said, “the T.M. practitioners brought about striking physiologic changes — a drop in heart rate, metabolic rate, and breathing rate — that I would subsequently label ‘the Relaxation Response.’ “

He titled his first book “The Relaxation Response,’’ which was a best-seller when it was published in 1975.

That response brought a measure of celebrity. Barbara Walters interviewed Dr. Benson on TV and he testified before Congress about the mind/body relationship.

“Because it was such a great hit, he had the opportunity to become a celebrity author and make gobs of money,’’ Fricchione said.

“He decided no, that wasn’t going to be it for him,’’ Fricchione added. “He understood if you choose to go in that direction, you really carve yourself out from being taken seriously as a researcher. That’s what he did. He stayed at Harvard and stuck to hard-won research findings.’’

His key finding was that there are documentable health benefits to meditating for 10 to 20 minutes each day:

Sit quietly and comfortably and pick a word, a phrase, or a prayer that fits within your belief system. Close your eyes, relax your muscles, and breathe slowly, saying your word or phrase as you exhale. Shrug it off if other thoughts intrude — say “oh, well’’ and return to repeating your word, phrase, or prayer.

The benefits, he said, are wide-ranging.

“Eliciting the relaxation response can help bring blood pressure under control with less medication,’’ Dr. Benson told a psychiatric conference at McLean Hospital in Belmont in 1980.

“Meditation also can reduce extra heart beats in cardiac arrhythmias, can ease circulatory problems, migraine and tension headaches, and is extremely useful in treating anxiety attacks,’’ he said. “The only side effects are the same as those of prayer.’’

Herbert Benson was born in Yonkers, N.Y., on April 24, 1935, and grew up there, a son of Hannah Schiller Benson, a homemaker, and Charles Benson, who ran seven stores in the wholesale produce business.

His father died young of heart disease, which contributed to Dr. Benson’s decision to pursue medicine and cardiology.

He graduated from Yonkers High School, received a bachelor’s degree in biology from Wesleyan University, and graduated from Harvard Medical School.

After his internship and residency, he served in Puerto Rico in the US Public Health Service.

Returning to Boston, he worked at what was known as the heart station in Boston City Hospital, which is now Boston Medical Center, and then took time to work in the lab where, years earlier, Dr. Walter Cannon had described the “fight or flight’’ classic response to stress.

When that occurs, the body’s metabolism, heart rate, and blood pressure increase. Dr. Benson said the relaxation response that meditation produced was a way to counter those effects.

Over the years, his research included meetings with the Dalai Lama and trips to India, where Dr. Benson studied the ability of certain Tibetan monks to raise their body temperatures during deep meditation.

Among Dr. Benson’s other books are “The Mind/Body Effect’’ (1979), “The Wellness Book’’ (1992), and “Timeless Healing: The Power of Biology and Belief’’ (1996).

In 1962, Dr. Benson married Marilyn Wilcher, whom he had met through friends when she was a Wellesley College student and he was at Harvard Medical School.

She formerly ran a catering business in Lexington, where they previously lived for many years, and was a cofounder of the Mind/Body Institute.

“He really cared about his family,’’ she said. “The kids and I were extremely important to him.

One example of that was that he always would be home for dinner. We had a family dinner every night, except when he was traveling.’’

Dr. Benson “always was upbeat,’’ said their son, Gregory of Maplewood, N.J. “He was really motivated, was always willing to give things a try, and take chances and go for something. And he did so in a joyful way.’’

“He was an unassuming, great man — a gentle scientist loved by those who knew him,’’ Henry said. “No one did more to advance the scientific and medical side of the mind/body connection.’’

In addition to his wife and son, Dr. Benson leaves a daughter, Jennifer of Chicago, and four grandchildren.

The family will hold a graveside service Wednesday in Mount Auburn Cemetery in Cambridge and will announce a Zoom gathering for later in the week.

“Herb was one of the most optimistic personalities I’ve met in medicine,’’ Fricchione said. “I think that was one of the keys to his ability to heal people.’’

Gregory said his father “really believed in the power of belief and the power of the mind. He believed that belief itself was healing.’’

Although, as Dr. Benson noted in a 1996 Globe interview, “I came to this not by belief, but from science. Honestly, I came to this, feet dragging.’’

At the outset, “they said what I was doing was not science. So I conducted two careers at the same time for years, one in cardiology and one in mind/body research,’’ he said. “If I had left rigorous science, my mind/body research would never have been accepted.’’

Bryan Marquard can be reached at bryan.marquard@globe.com.