The Mediterranean diet appears to be associated with longer telomere length — a marker of slower aging and thus long life, a  study published in the BMJ this week suggests.

The Mediterranean diet has been consistently linked with health benefits, including reduced mortality and reduced risk of chronic diseases, such as heart disease.

The diet is based on a high intake of vegetables, fruits, nuts, legumes (such as peas, beans and lentils), and (mainly unrefined) grains; a high intake of olive oil but a low intake of saturated fats; a moderately high intake of fish, a low intake of dairy products, meat and poultry; and regular but moderate intake of alcohol (specifically wine with meals).

Shorter telomeres, which are located on the end of chromosomes, are associated with lower life expectancy and greater risk of age-related diseases. Lifestyle factors, such as obesity, cigarette smoking, and consumption of sugar sweetened drinks, have all been linked to people having shorter telomeres than typically occur in people of a similar age. Oxidative stress and inflammation have also been shown to speed up telomere shortening.

Largest population-based study of Mediterranean-diet-associated telomere length

The U.S. researchers, led by Immaculata De Vivo, Associate Professor at Brigham and Women’s Hospital and Harvard Medical School, set out to examine whether adherence to the Mediterranean diet was associated with longer telomere length. They analyzed data on 4,676 healthy middle-aged women from the Nurses’ Health Study — an ongoing study tracking the health of more than 120,000 US nurses since 1976. Participants completed detailed food questionnaires and had a blood test to measure telomere length.

A diet score ranging from 0–9 points was calculated for each participant, with a higher score representing a closer resemblance to the Mediterranean diet.

After adjusting for other potentially influential factors, the results show that greater adherence to the Mediterranean diet was significantly associated with longer telomeres. Each one point change in diet score corresponded on average to 1.5 years of telomere aging.

However, none of the individual dietary components was specifically associated with telomere length, underlining the importance of examining dietary patterns in relation to health, not just separate dietary factors such as intake of whole grains, say the authors.

“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,” they write. “Our results further support the benefits of adherence to the Mediterranean diet for promoting health and longevity.”

A Mediterranean diet is also the cornerstone of dietary advice in cardiovascular disease prevention, and the fact that it also links with a biomarker of slower aging is reassuring, says Professor Peter Nilsson from Lund University, Sweden in an accompanying editorial.

He suggests that genetic background factors, reflecting ancestry, could probably explain some of the variation in the association between dietary patterns and telomere length, and that future studies on this question “should take into account the possibility of interactions between genes, diet, and sex.”

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Abstract of  Mediterranean diet and telomere length in Nurses’ Health Study: population based cohort study

Objective To examine whether adherence to the Mediterranean diet was associated with longer telomere length, a biomarker of aging.

Design Population based cohort study.

Setting Nurses’ Health Study, an ongoing prospective cohort study of 121 700 nurses enrolled in 1976; in 1989-90 a subset of 32 825 women provided blood samples.

Participants 4676 disease-free women from nested case-control studies within the Nurses’ Health Study with telomere length measured who also completed food frequency questionnaires.

Main outcome measure Association between relative telomere lengths in peripheral blood leukocytes measured by quantitative real time polymerase chain reaction and Alternate Mediterranean Diet score calculated from self reported dietary data.

Results Greater adherence to the Mediterranean diet was associated with longer telomeres after adjustment for potential confounders. Least squares mean telomere length z scores were −0.038 (SE 0.035) for the lowest Mediterranean diet score groups and 0.072 (0.030) for the highest group (P for trend=0.004).

Conclusion In this large study, greater adherence to the Mediterranean diet was associated with longer telomeres. These results further support the benefits of adherence to the Mediterranean diet for promoting health and longevity.