Effects of Extra-Virgin Olive oil and Fish Oil on Lipid Profile and Oxidative Stress in Patients with Metabolic Syndrome

Objective: 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).

Research Methods & Procedures: One hundred and two patients (81 female and 21 male) with MetS (aged 51.45 years) from the ambulatory of the University Hospital of Londrina, Paraná, Brazil participated in this intervention study. Patients were randomly assigned to one of four groups: the first group (control group - CG) was only instructed to maintain its usual diet; the second group (fish oil group-FO) received 3 g/d of fish oil n-3 fatty acids (ten capsules); the third group [extra-virgin olive oil group (OO)] received 10mL/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 n-3 fatty acids and 10mL/d of extra-virgin olive oil. MetS related markers and oxidative stress were measured at baseline and after 90 days.

Results: Differences across treatment groups showed a statistically significant decrease (p<0.05) in TC and 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 TRAP/AOPP (p<0.05) in FOO when compared to FO. In relation to baseline values, there was a significant decrease (p<0.05) in LDL-C values, and TC/HDL-C and LDL-C/HDL-C indexes in FOO. There was also a decrease (p<0.05) in hydroperoxides, in advanced oxidation protein products (AOPP) and in AOPP/ total radical-trapping antioxidant parameter (TRAP) index in FOO, and an increase (p<0.05) in TRAP/AOPP index in FOO and in TRAP/uric acid ratio in OO.

Conclusion: The present study provides evidence that increased dietary n-3 polyunsaturated fatty acids and extra-virgin olive oil have beneficial synergistic effects on lipid metabolism and oxidative stress in MetS patients.


Alex’s Notes: When it comes to dyslipidemia, two dietary interventions have shown to be successful. The first is the Mediterranean diet, which the principle source of fat is olive oil. The second is the omega-3 fatty acids of fish oil. So the question now becomes, does olive oil act synergistically with fish oil?

To answer this, 102 patients with metabolic syndrome were recruited to undergo one of four interventions for 90 days. Importantly, none had cardiovascular, thyroid, renal, hepatic, or gastrointestinal diseases, none followed a specific diet, and none supplemented fish oil or antioxidants. The researchers instructed the patients to not change their diets, alcohol intake, or physical activity throughout the three-month period. The groups were

  • Control group (CH) instructed to maintain lifestyle
  • Fish oil group (FO) received 3 g/day of fish oil (1800mg EPA & 1200 mg DHA) to be consumed at breakfast, lunch, and dinner
  • Olive oil group (OO) received 10mL/day of extra-virgin olive oil (containing 6.4g of oleic acid) at lunch and dinner
  • Fish & olive oil group (FOO) received 3g/day fish oil and 10mL/day olive oil

Hopefully the fish oil capsules were packaged properly.

Pill popping, oil drinking, 90 days later

There were no differences between the groups at baseline, and none of the persons drank alcohol regularly. The participants were majority obese white (74%) women (79%) with an average age of 51 years. Compared to baseline, after 90 days only the FOO group showed significant reductions in LDL-C (28 mg/dL), Total cholesterol to HDL-C ratio, and the LDL-C to HDL-C ratio. When comparing the groups themselves, FOO showed a significant reduction in total cholesterol and LDL-C compared to CG and OO, respectively.

When looking at markers of oxidative stress, both the CG and FOO reduced their AOPP, OO reduced their TRAP/Uric acid ratio, and FOO reduced their hydroperoxide and AOPP/TRAP ratio compared to baseline. Compared to one another, the FOO group significantly reduced their hydroperoxide index compared to CG and increased their TRAP/AOPP ratio compared to FO.

What does this mean?

I had the same question. The cholesterol changes indicate that fish oil and olive oil do act synergistically to reduce LDL-C, which in combination with olive oils ability to prevent LDL-C oxidation, makes for a powerful statin alternative. I do wonder how a larger sample size would have affected the outcomes, however, as it seems odd that no time-effect interactions were noted for the olive oil and fish oil groups independently.

Regarding oxidative stress,AOPPs may be a potential inducer of cellular inflammation in vivo under certain pathophysiological circumstances, and thus AOPPs are not only markers of oxidative stress, but also act as inflammatory mediators. The use of TRAP has been proposed to explore plasma antioxidant capacity. Thus, by FOO reducing AOPPs and increasing TRAP, it suggests that this combination provides antioxidant potential.


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