Researchers found that the regimen -- rich in whole grains, vegetables, fruits, legumes, nuts, fish and olive oil -- appears to be associated with longer telomere length, which are indicators of slower aging.
Telomeres are located on the ends of chromosomes -- much like the plastic tips on the end of shoelaces. According to geneticists, telomeres prevent chromosomes from fraying and scrambling the genetic codes they contain. These bits of genetic material naturally shorten with age, but they tend to shorten more slowly in healthy people.
Shorter telomeres have long been associated with a greater risk of age-related diseases and a shorter life span, experts say.
The new study was led by Immaculata De Vivo, an associate professor at Brigham and Women's Hospital and Harvard Medical School, in Boston. Her team looked at data from more than 4,600 participants in the ongoing Nurses' Health Study, which has been tracking the health of U.S. nurses since 1976.
The participants were given a score of 0 to 9 on how closely they followed a Mediterranean diet, with a higher score indicating greater adherence to the regimen.
After adjusting for other factors, the researchers concluded that telomeres aged more slowly for every point a person went up on the scale.
However, the intake of individual food items in the Mediterranean diet was not associated with telomere length, which shows the importance of overall eating patterns on health, De Vivo's team said.
"To our knowledge, this is the largest population-based study specifically addressing the association between Mediterranean diet adherence and telomere length in healthy, middle-aged women," the researchers wrote. "Our results further support the benefits of adherence to the Mediterranean diet for promoting health and longevity."
According to De Vivo's team, prior research has linked the Mediterranean diet with better heart health, as well as a lowered risk for chronic disease and death.
The study, published Dec. 2 in the BMJ, was not designed to prove that the Mediterranean diet slowed the shortening of telomeres; it could only show an association.
Still, one cardiologist said the findings make sense.
"Telomere length has been associated with aging -- with longer telomere length, there has been association with slower aging, and with a longer life expectancy," said Dr. Suzanne Steinbaum, director of Women and Heart Disease at Lenox Hill Hospital in New York City.
She noted that unhealthy habits might have the opposite effect on telomeres, however.
"Shorter telomeres are associated with obesity, cigarette smoking and the consumption of sugar," Steinbaum noted. On the other hand, "the Mediterranean diet is filled with antioxidants and anti-inflammatory foods in the form of fruits, vegetables, legumes," she said, and "there is an association with longer telomeres."
The American Heart Association has more about the Mediterranean diet.