Nov. 11, 2003 (Orlando) — A Mediterranean diet rich in olive oil and lean red meat can lower the levels of key inflammation and coagulation markers related to cardiovascular disease (CVD), a cross-sectional study suggests.
The study not only provides a pathophysiological explanation for the beneficial effects of a Mediterranean diet on the heart, but it also "clearly shows that this beneficial effect was independent of any other lifestyle factors," said Demosthenes Panagiotakos, PhD, lecturer in the department of nutrition and dietetics at Harokopio University of Athens in Greece.
Dr. Panagiotakos, who spoke here Monday at the American Heart Association (AHA) Scientific Sessions, noted that previous studies have suggested that adherence to a Mediterranean diet may reduce the risk of cardiovascular disease by up to 30%.
However, it is not fully understood how the diet exerts its protective effect, he said. "Some have suggested it lowers blood pressure; others speculate it reduces cholesterol levels. Still others say it is not the diet itself but other characteristics of people who follow the diet, such as a healthy lifestyle."
The new study, which applied multivariate analysis to tease out the effects of any confounding lifestyle factors, should help put an end to the debate, Dr. Panagiotakos said.
"The Mediterranean diet, independent of any other factor, reduces levels of inflammation and coagulation markers related to CVD risk," he told Medscape.
Alice H. Lichtenstein, DSc, vice-chair of the AHA's Nutrition Committee and Gershoff Professor of Nutrition, Science, and Policy at Gerald J. and Dorothy R. Friedman School of Nutrition, Science, and Policy at Tufts University in Boston, Massachusetts, agreed.
"While no one study ever puts an issue to bed, this research offers really strong data that diet makes a difference," she said.
The study enrolled 2,282 men and women, aged 18 to 89 years, without any history or signs of cardiovascular disease. The researchers used a validated food-frequency questionnaire, developed by the Greek National School of Public Health, to track consumption of red meat, chicken, fish, vegetables, legumes, pasta, salads, cereals, dairy products, sweets, and fruits among all participants.
Using those results, each participant was assigned a customized diet score, on a scale of 0 to 60 points, which corresponded to adherence to a Mediterranean diet. The participants were then divided into tertiles according to their scores.
Plasma levels of C-reactive protein, interleukin-6, homocysteine, tumor necrosis factor-alpha and fibrinogen as well as white blood cell count were measured after a 12-hour fast.
Univariate analysis showed that adoption of a Mediterranean diet was associated with a significant reduction in levels of all six markers of inflammation and coagulation, Dr. Panagiotakos reported.
In a multivariate analysis that controlled for body mass index, age, sex, education, and physical activity, adoption of the diet was associated with a significant drop in all markers except tumor necrosis factor-alpha, he said.
For each 10-point increase in diet score, there was a corresponding 0.22 mg/dL reduction in C-reactive protein levels, a 0.21 pg/ml reduction in interleukin-6, a 12.5 mg/dL decrease in fibrinogen, and a 0.87 mmol/L decrease in homocysteine levels ( P < .05), he said. Also, white blood cell count decreased significantly ( P < .05).
Further multivariate analysis showed that, compared with being in the lower quartile, adoption of the Mediterranean diet is associated with 14% lower risk of being in the higher quartile of fibrinogen levels (odds ratio [OR], 0.86; P < .01), a 10% lower risk of being in the higher quartile of homocysteine levels (OR, 0.90; P < .01), and a 17% lower risk of being in the higher quartile of C-reactive protein levels (OR, 0.83; P < .01).
According to Dr. Lichtenstein, the heart-healthy benefits most likely come from the diet as a whole, not from specific components.
"People are always trying to say, 'It's the vitamin E, it's the beta carotene,' or whatever," she said. "And then the next study proves them wrong. That's because it is the relative balance of all the vitamins, minerals and other components that makes a difference."
AHA 2003 Scientific Sessions: Abstract 3348. Presented Nov. 10, 2003.
Reviewed by Gary D. Vogin, MD
Medscape Medical News © 2003 Medscape
Cite this: Charlene Laino. Mediterranean Diet Lowers C-reactive Protein Levels - Medscape - Nov 11, 2003.