The Mediterranean diet may be one of the keys to long life, a new study suggests.

Researchers in Italy found that people living in mountain villages on the island of Sicily, who had lived to the age of at least 100, adhered closely to a diet rich in fruits, vegetables and whole grains, and low in red meat, refined carbohydrates and sweets.

One key aspect of the centenarians' diets was the low glycemic index, the researchers said. The glycemic index is a measure of how food affects a person's blood sugar levels: Foods with a high glycemic index (such as white bread) cause glucose levels to spike quickly after they are eaten, while foods with a low glycemic index (such as vegetables and legumes) cause blood sugar levels to rise more slowly and remain more constant over time.

Diets with a high glycemic index have previously been linked to an increased risk of Type 2 diabetes, whereas diets with a low glycemic index have been shown to protect against heart disease.

The study showed an association, not a cause-and-effect link between the diet and a long life, and more work is needed to confirm the findings.

Still, "to reach successful ageing, it is advisable to follow a diet with low quantity of saturated fat and high amount of fruits and vegetables rich in phytochemicals," which are compounds found in plants, the researchers wrote in their conclusion.

The findings were published April 23 in the journal Immunity and Ageing.

Researchers at the University of Palermo studied people living in the villages of Sicani Mountains, in central Sicily. They found 19 people between the ages of 100 and 107, out of a population of 18,328 inhabitants. That means the percentage of centenarians living in those villages is more than four times greater than the national average, the researchers said.

The centenarians answered detailed questions about their diet, and underwent a physical exam including blood tests. They were also evaluated for their cognitive abilities and their abilities to accomplish daily tasks independently.

The researchers found that the centenarians were in good health. The group was free of severe cognitive and physical impairments, the researchers said, though some were experiencing declines in their hearing or vision. Blood tests revealed that their cholesterol and triglycerides levels were normal.

All of the centenarians lived in homes with their families. They were physically active, and were not obese.

The group was also notable because nearly half (nine) of the centenarians were men, which translates to a percentage of male centenarians that is 11.5 times the national average, the researchers said.

Other factors besides diet likely also played a role in these centenarians' longevity, the researchers wrote.

Certain genes that control inflammation, along with the close support of family members and moderate consumption of alcohol, likely contributed to the participants' overall health.

Estimates show the number of centenarians in the world will approach 3.2 million by 2050, an 18-fold increase compared with the last century. Understanding the influence of diet on aging is important in the development of new strategies to extend lives, the researchers said.

Pass it on: Eating a Mediterranean diet may help in leading a long and healthy life.

Follow MyHealthNewsDaily on Twitter @MyHealth_MHND. Find us on Facebook.

Related on MyHealthNewsDaily:

Copyright 2012 MyHealthNewsDaily, a TechMediaNetwork company. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.