A Mediterranean diet rich in foods like olive oil, nuts, and fish may reduce the relative risk of coronary heart disease in people at high risk by 30 percent, according to a new study.

The study, conducted by University of Barcelona medical professor Ramon Estruch and his colleagues, is the first major clinical trial to successfully examine the impact of such a diet on a person’s susceptibility to heart attacks and strokes.

Harvard School of Public Health professor Frank M. Sacks, who was consulted by the researchers before the trial began about how to best design and conduct the study, pointed out positive effects revealed by the research.

“The Mediterranean diet pattern emphasizing nuts and extra-virgin olive oil protects the heart against blockages in the arteries and prevents the brain from strokes,” said Sacks.

Cardiologist Sekar Kathiresan of the Cardiovascular Disease Prevention Center at Massachusetts General Hospital called the study “quite an amazing feat.”

“It is a game-changer in coronary heart disease prevention,” he said.

According to Kathiresan, the study proves that the a dietary shift could be as effective as medicinal pills reducing the risk of heart attack.

Thus far there are two types pills that have been proven to reduce the risk of heart attacks—aspirin, which lowers blood clotting, and statins, which lower “bad” cholesterol. Aspirin reduces the risk of heart attacks by 20 percent, and statins by 25 percent.

Both Kathiresan and Sacks said that the one hole they saw in the study’s findings is that the researchers did not determine exactly which food or foods are create the benefits of such a diet.

But Sacks said he believes this lack of specificity is not a serious limitation since it is the change to an “overall Mediterranean diet pattern” that is key to gaining the health benefits.

“[The study] shows a healthy dietary pattern can prevent heart attacks and strokes by quite a lot. People should take a close look at their diet and try to change it in the direction of a Mediterranean diet,” said Sacks.

Sacks said that to follow this Mediterranean diet, people should begin by consuming less red meat, soda, and sweets, and consume more fish, nuts, vegetables, and fruit.