Healthy and at risk (hypercholesterolemic) subjects consumed during 4 weeks 45 g/d of either olive pomace oil (OPO) or high oleic acid sunflower oil (HOSO) as the only dietary fat in a randomized, crossover trial. The effects on blood lipids, glucose homeostasis, endothelial function, inflammatory cytokines, oxidative stress biomarkers and anthropometry were measured.

This is the first study on the potential health effects of consumption of olive pomace oil.

After a 3-weeks run-in, 34 healthy and 30 hypercholesterolemic subjects were randomized to consume either OPO or HOSO (45 g/d) during 4 weeks, followed by a 3-week wash-out during which volunteers consumed the same amount of normal sunflower oil. During all the study, other dietary sources of fat (oil, nuts, butter, etc.) were restricted. Food intake was monitored by 3-d food records in each intervention stage and volunteers were instructed to maintain their normal physical and dietary habits (except for the changes in the consumption of other oils and fats).

At the beginning and end of each intervention stage, blood and urine samples were obtained, and blood pressure and anthropometric measurements were performed. A complete batch of analysis were performed, including serum lipids, endothelial function (flow mediated dilation (FMD), endothelial nitric oxide synthase (eNOS), vascular (VCAM-1) and intercellular (ICAM-1) cell adhesion molecules, E- and P-selectins), inflammatory and anti-inflammatory cytokines, glucose homeostasis/insulin resistance, antioxidant status and biomarkers of lipid oxidation (malondialdehyde (MDA), LDLox, ferric reducing antioxidant power (FRAP), oxygen radical absorbance capacity (ORAC), ABTS (2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) quenching capacity) and anthropometry, along with determination of incretins, adipokines, and other clinical and hematological parameters.

Inclusion Criteria:

• Healthy volunteers (Total cholesterol < 200 mg/dL; LDL-cholesterol < 135 mg/dL)
• Hypercholesterolemic volunteers (Total cholesterol 200-300 mg/dL; LDL-cholesterol 135-175 mg/dL)

Exclusion Criteria:

• BMI > 30 Kg/m2
• Smokers
• Vegetarians
• Pregnant women
• Medication/consumption of vitamins, dietary supplements
• On antibiotic treatment 3 months before starting the study
• Digestive disorders/pathologies (gastric ulcer, Chron's disease, inflammatory bowel syndrome, etc.)
• Food allergies/intolerances

Oils were provided in unlabelled bottles (only differed in the colors of stoppers)