The reduced risk of cardiovascular disease seen in people who eat a Mediterranean diet may be attributable to the phenolic components of virgin olive oil, which repress several pro-inflammatory genes.

Phenols are micronutrients of olive oil; the extra-virgin varieties have a particularly large phenol fraction.

Researchers writing in the open access journal BMC Genomics studied the effects of eating a breakfast rich in phenol compounds on gene expression in 20 patients with metabolic syndrome, a common condition associated with increased risk of cardiovascular disease and type 2 diabetes.

The study participants ate controlled breakfasts, and for six weeks before the study they had to avoid all drugs, vitamin tablets and other supplements. While comparing the intake of of phenol-rich olive oil with low-phenol, researchers identified 98 differentially expressed genes.

"Several of the repressed genes are known to be involved in pro-inflammatory processes, suggesting that the diet can switch the activity of immune system cells to a less deleterious inflammatory profile, as seen in metabolic syndrome," said Francisco Perez-Jimenez from the University of Cordoba.

 According to Cordoba, "these findings strengthen the relationship between inflammation, obesity and diet and provide evidence at the most basic level of healthy effects derived from virgin olive oil consumption in humans. It will be interesting to evaluate whether particular phenolic compounds carry these effects, or if they are the consequence of a synergic effect of the total phenolic fraction".

Citation: Camargo et al., 'Gene expression changes in mononuclear cells from patients with metabolic syndrome after acute intake of phenol-rich virgin olive oil', BMC Genomics, April 2010, 11:253; doi:10.1186/1471-2164-11-253