NEW YORK — Philip W. Majerus, a biochemist who was credited as being the first to theorize that taking small doses of aspirin regularly can prevent heart attacks and strokes in vulnerable patients, died June 8 at his home in St. Louis. He was 79.

The cause was prostate cancer, his wife, Dr. Elaine Majerus, said. He had taught at the Washington University School of Medicine in St. Louis for almost 50 years.

Even before his findings were confirmed in a study by other researchers a decade later, Philip Majerus was taking aspirin daily.

“I was already convinced that aspirin prevented heart attacks,’’ he recalled in the journal Advances in Biological Regulation in 2014. “I was unwilling to be randomized into a trial where I might end up with the placebo. I refused to participate.’’

Dr. Majerus recommended that “all adults should take an aspirin daily unless they are among the few percent of the population that cannot tolerate the drug.’’ The cardiovascular benefit of aspirin was fully achieved by 50 to 75 milligrams daily, he said, and “there is no evidence that branded aspirin, which is much more expensive, is in any way superior to the generic version.’’

Later studies found that for people in their 50s who are vulnerable to heart disease, taking daily doses of aspirin reduces the risk of heart disease.

In 1998, Dr. Majerus received the Bristol-Myers Squibb Award for Distinguished Achievement in Cardiovascular Metabolic Research for his findings, which were credited with saving countless lives.

Dr. Majerus later theorized that aspirin could also be effective in preventing some forms of cancer, pointing the way to recent studies indicating that daily doses of aspirin also reduce the risk of colon cancer.

A Chicago native, Philip Warren Majerus received a bachelor of science degree from the University of Notre Dame in 1958, graduated from Washington University School of Medicine, and served as a resident at Massachusetts General Hospital.

In the 1970s, Dr. Majerus and his postdoctoral research fellow, Gerald Roth, focused on the impact of aspirin on platelets, small cells that precipitate clotting when a vessel is injured. They clump together and a clot forms to seal the wound.

He studied patients who were being treated for kidney failure and, to facilitate dialysis, had shunts, which can cause clotting, inserted in their arms. After six months, 18 of the 25 patients who were taking a placebo developed a blood clot, compared with six of the 19 who were given aspirin.