Mediterranean-inspired diet and inflammation

Nutrition Research Newsletter, April, 2006

Diet is of utmost importance for preventing cardiovascular disease and recent studies have shown reduced mortality in persons adhering to a Mediterranean diet. The mechanisms underlying the cardiovascular benefits of Mediterranean-inspired diets (MIDs) are not fully understood. These diets are associated with a lower level of LDL oxidation, which results from a higher presence of monounsaturated fatty acids and a less proinflammatory state. In addition, inflammation has an essential role in the development and progression of atherosclerosis. Therefore, a group of Swedish researchers investigated whether a MID provided to healthy subjects would affect the inflammatory process and endothelial indexes such as vasoregnlation and vascular endothelial growth factor (VEGF), and serum phospholipids fatty acid composition.

A total of 22 men and women received a MID or an ordinary Swedish diet (OSD) for four weeks in a crossover fashion. Blood samples were taken before the start of each diet and after the four-week diet period to measure concentrations of lipids and fatty acids, high sensitivity C-reactive protein and interleukin 6. Both before and after lipopolysaccharide stimulation, the number of leukocytes and platelets and VEGF and monocyte chemoattractant protein 1 were analyzed.

Compliance with the diets was excellent, and all the subjects tolerated the dietary changes well, as assessed by 24-hour recalls and return of uneaten food items. Energy intake, as determined from 24-hour recalls, was slightly lower during the MID period than during the OSD period, which resulted in a small but statistically significant lowering of BMI after four weeks of the MID versus the four weeks of the OSD. The plasma ratio of n-6 to n-3 fatty acids was substantially lower after the MID than after the OSD. Neither C-reactive protein nor interleukin 6 concentrations changed significantly after the MID was compared with the OSD. The total number of leukocytes and platelets was 10% and 15% lower, respectively, after the MID than after the OSD. Serum VEGF concentrations were lower after the MID than after the OSD.

Although there was no evidence of a relationship between inflammatory markers and acetylcholine-induced forearm vasodilation, several other variables suggest a beneficial reduction induced by MID. The MID reduced the number of platelets and leukocytes, and possibly as a consequence, lowered VEGF concentrations. Taken together, these observations are indicative of a beneficial influence of the MID, which may be linked to the marked reduction in the ratio of n-6 to n-3 fatty acids.

Anneli Ambring, Mats Johansson, Metre Axelsen, et al. Mediterranean-inspired diet lowers the ratio of serum phospholipid n-6 to n-3 fatty acids, the number of leukocytes and platelets, and vascular endothelial growth factor in healthy subjects. Ant J Clin Nutr ;83:575--581 (March 2006) [Reprints not available. Address correspondence to P Friberg, Department of Clinical Physiology, Sahlgrenska University Hospital, SE-413 45 Goteborg, Sweden. E-mail: peter.friberg@mednet.gu.se]