Mediterranean diet lowers levels of markers for inflammation and coagulation which have been linked to heart disease

People who eat more fruit, whole grains, vegetables, olive oil, and other components of the Mediterranean diet have lower levels of markers for inflammation and coagulation which have been linked to heart disease, according to a new study in the July 7, 2004 issue of the Journal of the American College of Cardiology.

“The benefits of this diet are very well known, but the mechanism is not well understood. We believe this is the first time it has been reported that the potential mechanism goes through the inflammation process,” said Demosthenes B. Panagiotakos, MSc, PhD with Harokopio University in Athens, Greece.

In this study by Christina Chrysohoou, MD, PhD et al., researchers at Harokopio University and the University of Athens used data from the ATTICA Study, which collected information on the health, diet, physical activity, as well as blood tests and other information, from 1,514 men and 1,528 women living in and around Athens, Greece. All the participants used for this report were free of known cardiovascular disease. The researchers focused on reported consumption of components of the Mediterranean diet, including daily servings of whole grains, fruits, vegetables, olive oil and low or non-fat dairy products. The diet also includes fish, poultry, potatoes, and nuts; but only occasional red meat. Moderate wine drinking is also included.

Participants who most closely followed the Mediterranean diet had lower levels of several markers of inflammation and coagulation than those whose diets were farthest from the desired diet. The Mediterranean diet was associated with average blood test scores that were 20 percent lower for C-reactive protein, 17 percent lower for interleukin-6, 15 percent lower for homocysteine, 14 percent lower for white blood cell counts, and 6 percent lower for fibrinogen. Borderline associations were found for some other markers of inflammation.

Because people who eat healthier diets also may be more likely to have other characteristics linked to good health, the researchers re-analyzed the data to try to take other health risk factors into account.

“We repeated the data analysis, after controlling for age, sex, smoking, physical activity, as well as financial and education status, body mass index, presence of hypertension, diabetes, hypercholesterolemia, and family history of coronary heart disease. The final models were robust and valid, as well as explained the data well. Therefore, we believe that we have strong evidences for the observed association,” Dr. Panagiotakos said.

While these results appear to provide strong clues to how the Mediterranean diet works to reduce heart disease risk, Dr. Panagiotakos said further work will be needed to link the diet and blood test markers to actual health outcomes, including rates of heart disease and death.

“This study, as a cross-sectional one, cannot establish causal relations but only generate hypotheses. Thus, future prospective studies (including the ATTICA study) are needed in order to confirm or refute our findings. Also, misreporting of food items consumed and especially alcohol consumption, due to social class, can be a potential confounder,” he said.

Carl J. Lavie, MD, FACC with the Ochsner Heart and Vascular Institute in New Orleans, who was not part of this research effort, said the results are in line with those from a study he and his colleagues recently reported.

“We demonstrated that nonpharmacologic therapy with cardiac rehabilitation and exercise training programs (ours utilizes the Mediterranean diet) led to nearly 40 percent reductions in C-reactive protein, which was independent of statin use and weight reduction,” Dr. Lavie said. “These new data add to our knowledge base regarding the potential benefits of a Mediterranean type diet.”

Frank B. Hu, MD, PhD, at the Harvard School of Public Health in Boston, who also was not connected with this study, agreed with the authors that lower levels of C-reactive protein and other inflammatory markers may help explain the benefits of the Mediterranean diet. However, he pointed out that result does not mean that pouring on the olive oil will prevent heart attacks.

“In reality, Mediterranean diet is not just olive oil; it is a healthy package with many components: fruits, vegetables, fish, whole grains, red wine, and less red meat, besides olive oil. Those who want to follow the Mediterranean diet should think beyond olive oil,” Dr. Hu said.

The American College of Cardiology, a 29,000-member nonprofit professional medical society and teaching institution, is dedicated to fostering optimal cardiovascular care and disease prevention through professional education, promotion of research, leadership in the development of standards and guidelines, and the formulation of health care policy.