Postprandial and short-term effects of dietary virgin olive oil on oxidant/antioxidant status.

It is generally believed that virgin olive oil consumption has beneficial effects, but little is known about its effects postprandially on oxidant/antioxidant status. The aim of this study was to determine changes in oxidative stress biomarkers and lipid profile after a single dose of virgin olive oil and after 1 wk of daily consumption. Sixteen subjects (9 men, 7 women) ingested 50 mL of virgin olive oil in a single dose. Blood samples were collected from 0 to 24 h. Thereafter, 14 participants (8 men, 6 women) followed a 1-wk 25 mg/d virgin olive oil dietary intervention. Blood samples were collected at the end of this period. Serum TAG (P = 0.016), plasma FA (P < 0.001), and lipid peroxidation products in plasma (P< 0.001) and VLDL (P = 0.007) increased, reaching a peak at 4-6 h, and returning to baseline values at 24 h after oil ingestion. The opposite changes were observed in plasma glutathione peroxidase (P = 0.001) and glutathione reductase (GR) (P = 0.042). No changes in LDL lipid peroxidation or resistance to oxidation were observed postprandially. At 24 h, plasma oleic acid remained increased (P < 0.05) and resistance of LDL to oxidation improved (P < 0.05). After 1 wk of virgin olive oil consumption, plasma oleic acid (P = 0.031), resistance of LDL to oxidation (P< 0.05), and plasma GR activity (P = 0.005) increased. These results indicate that changes in oxidant/antioxidant status occur after oral virgin olive oil. Virgin olive oil consumption could provide short-term benefits for LDL resistance to oxidation and in glutathione-related enzyme activities.