Applied nutritional investigationEffects of extra virgin olive oil and fish oil on lipid profile and oxidative stress in patients with metabolic syndrome

•The Mediterranean diet is a rich source of olive oil and fish oil.•Olive oil has shown beneficial results on lipid metabolism and oxidative stress.•Fish oil has shown beneficial results on lipid metabolism and oxidative stress.•Olive oil and fish oil have synergistic effects on lipid metabolism.•Olive oil and fish oil have synergistic effects on oxidative stress.

ObjectiveThe aim of this study was to verify if extra virgin olive oil and fish oil have a synergistic effect on lipid and oxidative stress parameters in patients with metabolic syndrome (MetS).MethodsThis intervention study included 102 patients (81 women and 21 men) with MetS (mean age 51.45 ± 8.27 y) from the ambulatory center of the University Hospital of Londrina, Paraná, Brazil. Patients were randomly assigned to one of four groups: Patients in the control group (CG) were instructed to maintain their usual diet; the second group (fish oil group [FO]) received 3 g/d of fish oil ω-3 fatty acids (10 capsules); the third group (extra virgin olive oil group [OO]) received 10 mL/d of extra virgin olive oil at lunch and dinner; and the fourth group (fish oil and extra virgin olive oil group [FOO]) received 3 g/d of fish oil ω-3 fatty acids and 10 mL/d of extra virgin olive oil. MetS related markers and oxidative stress were measured at baseline and after 90 d.ResultsDifferences across treatment groups showed a statistically significant decrease (P < 0.05) in total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C) when FOO was compared with CG and OO, respectively. Hydroperoxides showed a significant decrease (P < 0.05) when FOO was compared with CG, whereas there was an increase in total peroxyl radical-trapping antioxidant potential/advanced oxidation protein products (TRAP/AOPP; P < 0.05) in FOO when compared with FO. In relation to baseline values, there was a significant decrease (P < 0.05) in LDL-C values, and TC/high-density lipoprotein cholesterol (HDL-C) and LDL-C/HDL-C indexes in FOO. There was also a decrease (P < 0.05) in hydroperoxides, in AOPP and in AOPP/TRAP index in FOO, and an increase (P < 0.05) in TRAP/AOPP index in FOO and in TRAP/uric acid ratio in OO.ConclusionThe present study provides evidence that increased dietary ω-3 polyunsaturated fatty acids and extra virgin olive oil have beneficial synergistic effects on lipid metabolism and oxidative stress in patients with MetS.