Effect of olive oil consumption on serum resistin concentrations in healthy men

Resistin has been linked to atherosclerosis and inflammatory processes in humans. Some polyphenols have been shown to downregulate resistin expression in adipocytes. The effects of olive oil phenolics on resistin are not known; therefore, we investigated the impact of olive oil consumption on serum resistin as a function of the olive oils' phenolic content. In a randomized, controlled, cross-over study 38 healthy German men aged 38±2 years replaced their usual consumption of raw fat during 3 periods of 3 weeks each by 25 ml of virgin, common and refined olive oil varying in phenolic content. Serum resistin, blood lipids and urine biomarkers of subjects' compliance were analysed at baseline and at the end of each intervention period. The integration of olive oil in the subjects' habitual diet led to a decrease in total cholesterol (p=0.025) and triglycerides (p=0.013) independent of the content of phenolic compounds in the oil. Serum resistin concentrations were not affected by the olive oils' phenolic content. After low phenolic olive oil consumption, a decrease in serum resistin level was observed compared to medium and high phenolic olive oil (−0.4±0.1 ng/ml; p=0.040). Our results suggest that olive oil consumption has only marginal beneficial effects on serum resistin levels

The NUTRAOLEOUM Study, a randomized controlled trial, for achieving nutritional added value for olive oils

Background: Virgin olive oil, a recognized healthy food, cannot be consumed in great quantities. We aim to assess in humans whether an optimized virgin olive oil with high phenolic content (OVOO, 429 mg/Kg) and a functional one (FOO), both rich in phenolic compounds (429 mg/Kg) and triterpenic acids (389 mg/kg), could provide health benefits additional to those supplied a by a standard virgin olive oil (VOO). Methods/design: A randomized, double-blind, crossover, controlled study will be conducted. Healthy volunteers (aged 20 to 50) will be randomized into one of three groups of daily raw olive oil consumption: VOO, OVOO, and FOO (30 mL/d). Olive oils will be administered over 3-week periods preceded by 2-week washout ones. The main outcomes will be markers of lipid and DNA oxidation, inflammation, and vascular damage. A bioavailability and dose-response study will be nested within this sustained- consumption one. It will be made up of 18 volunteers and be performed at two stages after a single dose of each olive oil. Endothelial function and nitric oxide will be assessed at baseline and at 4 h and 6 h after olive oil single dose ingestion. Discussion: For the first time the NUTRAOLEUM Study will provide first level evidence on the health benefits in vivo in humans of olive oil triterpenes (oleanolic and maslinic acid) in addition to their bioavailability and disposition