Mediterranean-style diets, rich in healthy fats from olive oil or nuts, may be better for the heart than low-fat regimens, a new study shows.

Spanish researchers found that the traditional Mediterranean diet bested a low-fat diet in helping older adults improve their cholesterol, blood pressure and blood sugar levels. The findings, published in the Annals of Internal Medicine, add to evidence that diets rich in healthy fats offer a better heart prescription than diets that limit fat altogether.

Mediterranean-style eating generally means plenty of fruits, vegetables and whole grains, limited amounts of red meat and processed foods, and a relatively high amount of fat from olive oil and nuts. Studies have shown that people living in the Mediterranean region have lower rates of heart disease, despite their high fat intake.

Experts believe the benefit stems from the fact that the unsaturated fats found in olive oil and nuts actually help protect the cardiovascular system.

Olive oil is mostly monounsaturated fat, and virgin olive oil - which is minimally processed - retains the fruit’s natural antioxidants, as well as nutrients that may help reduce inflammation in the blood vessels. Similarly, nuts contain unsaturated fats and other nutrients thought to be heart-protective.

The researchers, lead by Dr. Ramon Estruch of the University of Barcelona, found that it didn’t matter whether study participants got their healthy fat largely from olive oil or from nuts. The subjects assigned to either diet group that includes fats tended to see greater improvements in cholesterol, blood pressure and blood sugar than their peers who followed a low-fat diet.

This means the effects of the Mediterranean diet were moving “in the right direction,” Estruch of the University of Barcelona, told Reuters Health. Longer follow-up, he said, is needed to see whether the benefits translate into fewer heart attacks and strokes.

The study included 769 men and women between 55 and 80 years old who had type 2 diabetes or multiple other risk factors for heart disease and stroke, such as smoking, high blood pressure and heavy body weight.

For three months, participants followed one of three diets: a low-fat regimen that advised cutting down on all types of dietary fat; a Mediterranean diet that emphasized virgin olive oil as the prime fat source; or a Mediterranean diet in which walnuts, hazelnuts and almonds provided a large amount of overall dietary fat.

By the end of the study, those on either Mediterranean diet showed small improvements in their “good” HDL cholesterol levels, while the low-fat group showed an HDL decline - something that is known to happen with low-fat diets.

Both Mediterranean diet groups also had an overall improvement in blood pressure and blood sugar levels, while those of the low-fat group were essentially unchanged.

Men and women who got most of their fat from olive oil also had a decline in a blood substance called C-reactive protein, a marker of chronic inflammation in the body.

The study did not assess whether virgin olive oil or nuts were the healthier fat source, Estruch said, and it’s probably best to include both for a healthful diet.

SOURCE: Annals of Internal Medicine, July 4, 2006.