Boston, MA - A new analysis of data from the Nurses' Health Study has shown that women whose diets most closely resemble a traditional Mediterranean diet are significantly less likely to develop heart disease and stroke [1].

Lead researcher Dr Teresa T Fung (Harvard School of Public Health, Boston, MA) told heartwire that many other studies have looked at the effects of this diet on cardiovascular mortality, but this is one of few with enough participants to look at nonfatal events and also is the first to examine stroke as a separate outcome. Fung and colleagues report their findings online February 16, 2009 in Circulation.

"What this adds to the existing literature is that it shows a reduced risk of nonfatal events as well," she notes. "My take on this is that all the data from different studies with different types of dietary patterns are pointing in the same kind of direction: a minimally processed, mostly plant-based diet, with an abundance—not just in terms of quantity but in terms of variety—of different plant foods and fish. I will single out fish because we included fish in our score. Oily fish seem to have a very strong relation in terms of being beneficial."

Fung and colleagues used data on 74 886 women who participated in the Nurses' Health Study, and the current analysis averaged data from six different dietary assessments self-reported between 1984 and 2002. Previous studies have shown an association between the Mediterranean diet and a reduced risk of cardiovascular death in both men and women, they note. 

They calculated the Alternate Mediterranean Diet (aMed) score, a measure constructed to assess US-based diets for their similarity to a traditional Mediterranean diet, for the women and divided them into quintiles. Relative risks for incident coronary heart disease, stroke, and combined fatal cardiovascular events were estimated and adjusted for cardiovascular risk factors.

During 20 years of follow-up, there were 2391 incident cases of CHD, 1763 incident cases of stroke, and 1077 cardiovascular disease deaths (fatal CHD and strokes combined).

Women in the top aMed quintile were at lower risk for both CHD and stroke compared with those in the bottom quintile (relative risk for CHD 0.71; p for trend <0.0001; relative risk for stroke 0.87; p for trend=0.03).

CVD mortality was also significantly lower among women in the top quintile of the aMed score (relative risk 0.61; p for trend <0.0001).

"These are dramatic results," says Fung. "We found that women whose diets look like the Mediterranean diet are not only less likely to die from heart disease and stroke, but they are less likely to have those diseases."

She stressed that these results—particularly the stroke finding—would need to be replicated in men, however.

Compared with a typical US diet, the Mediterranean-type diet requires a shift toward a more plant-based diet, which means eating less meat and getting more of the day's protein from plant sources such as beans and nuts, Fung explained.

"I think the Mediterranean diet is by far one of the easiest to follow because there are no extremes," she added. "It doesn't necessarily mean people have to eat vegetarian. You can eat red meat, beef, and pork only once or twice a month, eat fish at least once a week, and eat more chicken. The types of food common to the Mediterranean diet are pretty easy to get as well.  It has a good amount of plant oils, so you are not cutting out fats." 

She fears, however, that the typical US diet pattern of fast food and red meat may be replacing the Mediterranean diet even in Mediterranean countries, noting, "Fast food restaurants are becoming more common over there."