New research from Spain confirms the benefit of a Mediterranean diet to a healthy heart.

In an analysis of more than 40,000 Spanish adults followed for an average of 10 years, researchers found that sticking to a Mediterranean diet significantly reduced the risk of a first heart attack or other heart disease-related event.

Specific components of a Mediterranean diet differ from region to region but, generally, the key features include high consumption of olive oil, plant-based foods such as fruits, vegetables, legumes, whole-grain cereals, nuts and seeds. Fish is favored over other meat sources with relatively low consumption of red meat. Alcohol, especially red wine, and dairy products are used in moderation.

For years, evidence has been accumulating regarding the protective effects of a Mediterranean diet against heart disease, Genevieve Buckland and associates at the Catalan Institute of Oncology in Barcelona note in the American Journal of Epidemiology.

Studies of varying sizes and designs have shown that a Mediterranean diet can reduce the risk of death in people who’ve had a heart attack, curb the risk of stroke, and boost survival in people living with heart disease, they note.

However, Buckland and associates were concerned that weaknesses in previous research limited the strength of conclusions. To investigate further, they used data collected between 1992 and 2004 from 41,078 healthy men and women from five Spanish centers involved in the 10-country European Prospective Investigation into Cancer and Nutrition, or EPIC, study.

The participants, whose average age was 49 at enrollment, provided information on what and how much they ate. The researchers also took body measurements, asked about behaviors such as smoking and physical activity, and medical history.

Each participant was given a score on an 18-point scale based on how closely their diet adhered to the Mediterranean ideal; the higher the score, the higher the adherence.

During an average follow-up of 10.4 years, 609 of the study participants suffered a heart attack or severe chest pain called unstable angina requiring intervention. Nine of them died.

When the researchers compared these heart events with Mediterranean diet scores and adjusted for confounding factors, they found that the higher the score (and adherence to the Mediterranean diet) the lower the risk of heart disease.

Specifically, high adherence, compared with low adherence, to the Mediterranean diet was associated with a 40 percent reduced risk of a first heart disease-related event, they report.

Heart disease is a top killer worldwide, accounting for roughly 30 percent of all deaths, equal to approximately 17 million deaths annually, the investigators note. Nearly half of these deaths are due to heart disease.

It’s thought that 80 percent of heart attacks and related events could be prevented by modifying behaviors - like adopting a healthy diet. And the current study suggests that drastic diet changes may not be necessary.

Each 1-unit increase in the Mediterranean diet score was associated with a 6 percent reduced risk of heart disease, Buckland and colleagues report. Even a 2-unit increase in Mediterranean score, “which required less drastic and more feasible dietary changes, has a protective effect,” they report.

The researchers say more study is needed to pinpoint key protective components of the Mediterranean diet and how these components confer their protective effects.

In the meantime, however, their results add to a growing body of evidence pointing to the heart health benefits of a diet rich in olive oil, plant-based foods, and fresh fish and low in red meats.

SOURCE: American Journal of Epidemiology, December 15, 2009.