The Mediterranean diet has been touted as a lifesaver for years, but a new study in BMJ suggests it may keep people genetically younger and even counter the effects of smoking and obesity on longevity.
The diet is rich in vegetables, whole grains, olive oil, fish, and fruits, but low in dairy and meat. Previous research has shown that it can reduce the risk of heart attack and stroke.
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For the latest study, Harvard researchers examined data of 4,676 middle-age, healthy women from the Nurses' Health Study, which is ongoing and has been tracking the health of approximately 120,000 nurses since 1976. The women ranked their diets on a scale of one to nine in relation to the ideal Mediterranean diet, the ideal being nine.
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Over a 20-year period, the researchers looked at the length of the women's telomeres, ends of chromosome caps which are necessary for cell division and naturally shorten over time. Short telomeres have been linked to stress, heart disease, cancer, diabetes, and shorter lifespans.
They found that women who stuck to a Mediterranean diet had longer telomeres than their peers did, even when controlling for smoking, physical activity, body mass index, and additional factors. A one-point change on the diet adherence scale correlated to 1.5-years in additional telomere aging.
According to study co-author Marta Crous-Bou, a postdoctoral fellow at Harvard Medical School, the aging difference is comparable to that between smokers and nonsmokers.
Moreover, following the Mediterranean diet "could balance out the 'bad effects' of smoking and obesity" due to the anti-inflammatory and antioxidant effects, says co-author Immaculata De Vivo, an associate professor at Brigham and Women's Hospital in Boston and Harvard Medical School.
However, some experts warn that the findings do not prove causality. "That said, this large well-conducted study is consistent with the hypothesis that dietary interventions may lead to substantial improvements in health," says David Llewellyn, a senior research fellow in clinical epidemiology at University of Exeter who was not involved with the study.
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De Vivo says her team hopes to study the effects of the diet men and identify which components of the diet have the largest effect on telomere length (Lee, CNN, 12/3; Bakalar, "Well," New York Times, 12/2; Roberts, BBC News, 12/2).