As evidence continues to build that the Mediterranean diet is among the healthiest on the planet, Boston researchers reported Tuesday that a diet rich in olive oil, fish, and plant foods, as well as a glass of wine with meals, could lead to a moderately longer life span.
The study, published in the British Medical Journal, examined nutritional data from 4,676 women participating in the well-known Harvard Nurses’ Health Study, and determined that those whose dietary habits hewed closest to the Mediterranean diet had longer telomeres, which protect the ends of a cell’s chromosomes and shorten with age.
“We know that having shorter telomeres is associated with a lower life expectancy and a greater risk of cancer, heart disease, and other diseases,” said study coauthor Immaculata De Vivo, an associate professor of medicine at Brigham and Women’s Hospital. “Certain lifestyle factors like obesity, sugary sodas, and smoking have been found to accelerate telomere shortening, and now our research suggests the Mediterranean diet can slow this shortening.”
Mediterranean diet components such as vegetables, fish, and wine are rich in antioxidants and have anti-inflammatory effects that could protect against cell aging, but the researchers didn’t find that any single food offered more benefits than another. Rather, it was the combination of dietary components — rated on a scale of 0 to 9, with a higher score more closely resembling the Mediterranean plan — that predicted telomere length.
Each one point change in diet score corresponded to a greater telomere length and appeared to add 1½ years of life, De Vivo said. The researchers controlled for other lifestyle factors that may have affected the results, such as exercise, smoking, and age.
New York University nutrition professor Marion Nestle, who was not involved in the study, said the findings should be interpreted with caution because the methods used by the researchers to connect a woman’s dietary intake with telomere lengths do not prove that diet alters telomeres.
“With that said, the study says eating healthfully is good for you,” Nestle added. “It might even make you live a year or so longer.”
A clinical trial published last year in the New England Journal of Medicine found that Spanish participants at increased risk for heart disease who were randomly selected to follow a Mediterranean diet had 30 percent fewer heart disease deaths, strokes, and heart attacks than those randomly assigned to a group that received generic nutrition advice to reduce sweets and eat fewer processed foods.
Another small clinical trial published last year involving 35 men in their 50s and 60s found that those who adopted for five years several lifestyle changes — including following a vegan diet, taking fish oil supplements, and engaging in regular exercise and meditation — experienced a 10 percent lengthening of their cell telomeres.
“The Mediterranean diet is two-thirds of the way toward a whole foods plant-based diet, but it begs the question as to whether it’s the optimal diet,” said Dr. Dean Ornish, president of the Preventive Medicine Research Institute, who led the telomere clinical trial involving middle-aged men. “We’ve found that when people make bigger changes, as an intervention, they could actually lengthen their telomeres,” rather than just slow their shortening.
In the latest study, the Brigham researchers found that women who followed other healthful diet approaches — eating chicken and low-fat dairy foods in addition to fruits, vegetables, and legumes — also had longer telomeres than those who ate a typical American diet filled with hamburgers, bacon, sweets, and fried foods. The Mediterranean diet followers, however, had the longest telomeres on average.
Genetic differences in telomere length that vary by ethnicity might explain some of the difference, wrote Peter Nilsson, a professor of medicine at Lund University in Sweden, in an editorial that accompanied the study. It could be that those born with longer telomeres are also more likely to gravitate toward a Mediterranean-style diet because of cultural preferences.