Extra virgin olive oil improves post-prandial glycemic and lipid profile in patients with impaired fasting glucose.

BACKGROUND & AIMS: Extra virgin olive oil (EVOO) improves post-prandial glycaemia in healthy subjects but it has never been investigated if this can be detected in pre-diabetic patients. We investigated if EVOO affects post-prandial glucose and lipid profile in patients with impaired fasting glucose (IFG). METHODS: Thirty IFG patients were randomly allocated to a meal containing or not 10 g of EVOO in a cross-over design. Before, 60 min and 120 min after lunch a blood sample was taken to measure glucose, insulin, Glucagon-like peptide-1 (GLP1), dipeptidyl-peptidase-4 (DPP4) activity, triglycerides (TG), total cholesterol, HDL-cholesterol and Apo B-48. RESULTS: The meal containing EVOO was associated with a reduction of glucose (p = 0.009) and DPP4 activity (p < 0.001) and a significant increase of insulin (p < 0.001) and GLP-1 (p < 0.001) compared with the meal without EVOO. Furthermore, the meal containing EVOO showed a significant decrease of triglycerides (p = 0.002) and Apo B-48 (p = 0.002) compared with the meal without EVOO. Total cholesterol and HDL cholesterol levels did not significantly change between the two groups. CONCLUSIONS: This is the first study to show that in IFG patients EVOO improves post-prandial glucose and lipid profile with a mechanism probably related to incretin up-regulation.

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 = 25) or Mediterranean diet with EVOO (10 g) or corn oil (10 g) (second study, n = 25). Oxidative stress biomarkers including platelet reactive oxidant species (ROS) and 8-iso-PGF2α-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-PGF2α-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.