Chicago, IL - Two new studies examining the Mediterranean diet, coupled with other risk-reducing behaviors, provide not only insights into the impact of these lifestyle modification but also a mechanism by which the benefits might accrue. Experts says the message from the studies is clear: eat well, be active, and the impact on health will be bigger than all of the disease treatments currently being devised and implemented in the US and elsewhere.

"As a society, the US spends billions on chronic-disease treatments and interventions for risk factors," Drs Eric Rimm and Meir Stampfer (Harvard University, Cambridge, MA) write in a September 22, 2004 editorial in the Journal of the American Medical Association.1 "Although these are useful and important, a fraction of that investment to promote healthful lifestyles for primary prevention among individuals at all ages would yield greater benefit."

Rimm and Stampfer's editorial accompanies the publication of Healthy Ageing: A Longitudinal Study in Europe (HALE) by Dr Kim Knoops (Wageningen University, the Netherlands) and colleagues2 and that of a second study, by Dr Katherine Esposito (Second University of Naples, Italy) and colleagues, examining the effects of the Mediterranean diet on endothelial cell function and in reducing vascular inflammatory markers in patients with the metabolic syndrome.3

HALE investigated the benefits of a diet rich in plant foods and fish, but low in meat, dairy products, and saturated fats, coupled with regular physical activity, moderate alcohol consumption, and nonsmoking, in more than 1500 healthy men and 832 women between the ages of 70 and 90. Over the course of 10 years, they report, the study participants who adhered to a Mediterranean diet, drank moderately, exercised regularly, and didn't smoke slashed their mortality rate by two thirds. Each component of the analysis was also independently associated with lower mortality. Similar reductions in mortality were seen for specific types of deaths, including cardiovascular, coronary, and cancer.

"This supports the hypothesis that participants who follow a Mediterranean type of diet and maintain a healthful lifestyle are less likely to die from all-cause and cause-specific mortality even at ages 70 to 90," Knoops et al write.

In the second study, Esposito and colleagues randomized 180 men and women diagnosed with the metabolic syndrome to either a Mediterranean diet or a "prudent diet." Of note, the nutrient composition of the two diets (50%-60% carbohydrates, 15% protein, <30% fat) was similar between the two diets.

After two years, the investigators found that while physical activity levels had increased in both groups to the same degree, patients on the Mediterranean diet lost more weight than the control group and had lower levels of CRP and less insulin resistance. Likewise, participants on the Mediterranean diet saw their total cholesterol and triglycerides go down and their HDL go up over the course of the study, improvements that were significantly greater than participants on the prudent diet. Suggesting an important mechanistic explanation of benefit, endothelial function improved in the Mediterranean diet group but remained stable in the control group, although this difference was not statistically significant. Strikingly, after two years on their respective diets, only 40 out of 90 patients in the Mediterranean diet still had features of the metabolic syndrome, compared with 78 out of 90 in the control group.

"The results of this study represent the first demonstration, to our knowledge, that a Mediterranean-style diet rich in whole grains, fruits, vegetables, legumes, walnuts, and olive oil might be effective in reducing both the prevalence of the metabolic syndrome and its associated cardiovascular risk," Esposito et al write.

She and her coauthors hypothesize that the benefits of the diet might be through a reduction in low-grade inflammation associated with metabolic syndrome. "Although weight reduction remains a cornerstone of therapy for the metabolic syndrome, from a public-health perspective adoption of a diet similar to that investigated herein may provide further benefit on cardiovascular risk, especially in patients who do not lose weight."

In their editorial, Rimm and Stampfer explore some of the pitfalls of studies attempting to gauge the benefits of lifestyle changes on health outcomes. Even estimating food consumption or energy output is fraught with problems, they note.

"Although understanding of the relation of lifestyle and health outcomes will continue to be refined, information available now is sufficient to take action."