Background:Oleic acid, polyphenols, and other components abundantly present in olive oil are thought to be partly responsible for the antiatherogenic effects attributed to the Mediterranean diet. One of the expected outcomes is a positive impact on the lipoprotein spectrum, but also other benefits are to be expected.Material/Methods: The analysis was conducted on 28 outpatients older than 50 years of age (mean age 68.1, 95%CI 64.9–71.3). The supplement was taken for 6 weeks and involved daily consumption of 2 tablespoons (approx. 20 g) of extra-virgin olive oil as part of the subjects’ habitual diets, without changing their usual total energy and fat consumption. This phase was followed by a 2-month wash-out.Results: After dietary supplementation with olive oil, serum total- and LDL-cholesterol mean concentrations were lowered by 0.818 mmol/l (p<0.00002; 95% CI –1.142 to –0.493 mmol/l) and 0.782 mmol/l (p=0.00013; 95% CI –1.141 to –0.423 mmol/l), respectively. There was also a significant decline in the total-to-HDL and LDL-to-HDL cholesterol ratios (p<0.03 and p<0.015). Linolic and arachidonic acid content in serum phospholipids decreased significantly (p<0.01 and p<0.001, respectively). The n-3 PUFAs were not affected.
Conclusions: These results point to an overwhelmingly beneficial influence of olive oil on the lipoprotein spectrum. The statistically significant reduction in arachidonic acid may even be regarded as clinically desirable. An excellent complementarity between the effects of MUFAs and long-chain n-3 PUFAs is to be expected.

Keywords: Arachidonic Acid, Cholesterol - blood, Dietary Supplements, Fatty Acids, Unsaturated - blood, Hypercholesterolemia - blood, Hypercholesterolemia - diet therapy, Lipids - blood, Oleic Acid - pharmacology, Plant Oils - pharmacology, Triglycerides - blood, Arachidonic Acid, Cholesterol - blood, Dietary Supplements, Fatty Acids, Unsaturated - blood, Hypercholesterolemia - diet therapy, Lipids - blood, Oleic Acid - pharmacology, Plant Oils - pharmacology, Triglycerides - blood