The Mediterranean diet is a well-known weapon in the fight against heart disease, but exactly how effective is it?

Researchers led by Dr. Ramón Estruch, from the Department of Internal Medicine at the Hospital Clinic of Barcelona, put the Mediterranean diet to the test against a low-fat diet.

They followed participants to track rates of heart attack, stroke and heart-disease-related death. After nearly five years, the results were so striking for one group that the study was stopped early, according to research published online by the New England Journal of Medicine.

The group that showed the least heart problems and lowest rate of heart disease deaths? Those who ate a Mediterranean diet high in extra-virgin olive oil. Coming in at a close second were participants who ate a Mediterranean diet high in nuts.

Compared with those eating the low-fat diet, the extra-virgin-olive-oil group showed a 30% lower risk of having a heart attack, stroke or dying of heart disease after five years, while those consuming the Mediterranean diet with more nuts showed a 28% lower risk of these outcomes.

"We think the strength of this study comes from the fact that we measured hard outcomes and not just blood pressure or changes in cholesterol levels," Estruch said. "We really believe the Mediterranean diet lowers incidence of (heart attack), stroke and cardiovascular deaths."

The new findings are published online in the New England Journal of Medicine.

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