Extra virgin olive oil blunt post-prandial oxidative stress via NOX2 down-regulation.

Objective: Olive oil protects against cardiovascular disease but the underlying mechanism is still unclear. We speculated that olive oil could inhibit oxidative stress, which is believed to be implicated in the atherosclerotic process. Methods and results: Post-prandial oxidative stress and endothelial dysfunction were investigated in twenty-five healthy subjects who were randomly allocated in a cross-over design to a Mediterranean diet added with or without extra virgin olive oil (EVOO, 10 g) (first study, n ¼ 25) or Mediterranean diet with EVOO (10 g) or corn oil (10 g) (second study, n ¼ 25). Oxidative stress biomarkers including platelet reactive oxidant species (ROS) and 8-iso-PGF2a-III, activity of NOX2, the catalytic sub-unit of NADPH oxidase, as assessed in platelets and serum, serum vitamin E and endothelial dysfunction, were measured before and 2 h after lunch. In the first study a significant increase of platelet ROS, 8-iso-PGF2a-III, NOX2 activity, sE-selectin, sVCAM1 and a decrease of serum vitamin E were detected in controls but not when EVOO was included in the Mediterranean diet; oxidative stress and endothelial dysfunction increase were also observed in the second study in subjects given corn oil. A significant correlation was found between NOX2 activity and platelet oxidative stress. In vitro study demonstrated that EVOO but not corn oil significantly decreased platelet and PMNs oxidative stress and NOX2 activity. Conclusion: The study provides the first evidence that post-prandial oxidative stress may be triggered by NOX2 up-regulation. EVOO but not corn oil, is able to counteract such phenomenon suggesting that addition of EVOO to a Mediterranean diet protects against post-prandial oxidative stress.