Following a Mediterranean diet substantially lowered the risk of heart attack and stroke in at-risk individuals – by almost 30 percent in five years – according to the results of a new study. Fruits, vegetables, fish and healthy fats such as olive oil and nuts take center stage in Mediterranean cuisine.

The PREDIMED project at the University of Barcelona (UB) aimed to assess the efficacy of the Mediterranean diet in the primary prevention of cardiovascular diseases. The results were published in February in The New England Journal of Medicine online.

Each of the 7,477 volunteer study participants had at least one major cardiovascular risk factor, including diabetes, obesity, high cholesterol, family history of heart disease or smoking. The results show that the Mediterranean diet, when supplemented with either extra-virgin olive oil or tree nuts, can reduce the risk of already at-risk individuals suffering a cardiovascular death, a myocardial infarction or a stroke by 30 percent.

“These results support the benefits of the Mediterranean diet for cardiovascular risk reduction,’’ said lead researcher Ramon Estruch, M.D., Ph.D. ‘’They are particularly relevant given the challenges of achieving and maintaining weight loss. The results of our trial might explain, in part, the lower cardiovascular mortality in Mediterranean countries than in northern European countries or the United States.’’

Estruch, a member of the University of Barcelona’s Faculty of Medicine, collaborated with researchers from the school’s Natural Antioxidant Research Group to perform the study. The research is part of the PREDIMED project, a multi-tiered project that began in 2011 to study the effects of the Mediterranean diet on the primary prevention of cardiovascular diseases.

The study followed 7,447 people over the course of five years. They were divided into three dietary intervention groups: a Mediterranean diet supplemented with extra-virgin olive oil, a Mediterranean diet supplemented with nuts (walnuts, almonds, hazelnuts), and a low-fat diet (animal and vegetable).

A dietician visited each participant every three months, and participants attended dietary training group sessions in which they received detailed information about the Mediterranean and the low-fat diets and the food included in each one. Participants were provided with shopping lists, menus and recipes adapted to each type of diet and each season of the year. The participants were not told to cut calories or start exercising.

During the study, participants following the olive-oil or nuts Mediterranean diets received a liter of extra virgin olive oil each week to use freely, and nuts (15 grams of walnuts, 7.5 grams of almonds and 7.5 grams of hazelnuts for a total of 30 grams per day). Other recommended foods included fruits and vegetables, legumes, a mixture of tomato, onion and garlic, and wine with meals. Processed food, red meats and baked goods were discouraged.

After five years, participants who followed either of the two types of Mediterranean diets showed a substantial reduction in the risk of suffering a cardiovascular death, a myocardial infarction or a stroke.

Previous studies have shown how following a Mediterranean diet can reduce belly fat, manage metabolic syndrome, fight existing heart disease and reduce the chances of a second cardiac event, but this is the first study to show the diet’s ability to reduce the risk of a first heart attack or stroke in at-risk individuals.

The results of the PREDIMED study indicate that a high-vegetable fat diet is healthier at a cardiovascular level than a low-fat diet. These findings counter the idea that it is necessary to reduce fats in order to improve cardiovascular health.