The olive tree, Olea europaea, is native to the Mediterranean basin and parts of Asia Minor. The fruit and compression-extracted oil have a wide range of therapeutic and culinary applications. Olive oil also constitutes a major component of the “Mediterranean diet.”
The chief active components of olive oil include oleic acid, phenolic constituents, and squalene. The main phenolics include hydroxytyrosol, tyrosol, and oleuropein, which occur in highest levels in virgin olive oil and have demonstrated antioxidant activity. Antioxidants are believed to be responsible for a number of olive oil’s biological activities.
Oleic acid, a monounsaturated fatty acid, has shown activity in cancer prevention, while squalene has also been identified as having anti cancer effects. Olive oil consumption has benefit for colon cancer and breast cancer prevention. The oil has been widely studied for its effects on coronary heart disease (CHD), specifically for its ability to reduce blood pressure and LDL cholesterol.
Antimicrobial activity of hydroxytyrosol, tyrosol, and oleuropein has been demonstrated against several strains of bacteria implicated in intestinal and respiratory infections.
Health Benefits of Olive Oil
Although it is difficult to isolate individual dietary factors, cumulative evidence suggests that olive oil, used as primary source of fat by Mediterranean populations, may play a key role in the observed cardiovascular benefit.
Numerous studies have shown that high olive oil intake reduces blood pressure. These positive effects of olive oil have frequently been ascribed to its minor components, such as alpha-tocopherol, polyphenols, and other phenolic compounds that are not present in other oils.
The blood pressure lowering effect of olive oil is also caused by its high oleic acid (OA) content (approximately 70-80%). Olive oil intake increases OA levels in membranes, which regulates membrane lipid structure (H(II) phase propensity) in such a way as to control G protein-mediated signaling, causing a reduction in blood pressure.
The results of a study of a group of 160 healthy men from non-Mediterranean regions suggest that a moderate consumption of olive oil could be used as an effective tool to reduce systolic blood pressure of healthy men who do not typically consume a Mediterranean diet.
Coronary Heart Disease
According to epidemiological and metabolic studies monounsaturated fatty acids (MUFAs) seem to exert a protection against coronary heart disease risk. In a study of 700 males and 148 female patients with first event of an acute coronary syndrome (ACS), it was concluded that exclusive use of olive oil during food preparation seems to offer significant protection against coronary heart disease and was associated with 47% lower likelihood of having ACS, irrespective of various clinical, lifestyle and other characteristics of the participants.
Lower LDL Cholesterol
Olive oil decreases LDL cholesterol and increases HDL cholesterol, and also reduces oxidative stress due to polyphenols, which are able to scavenge free radicals and protect LDL (Low-density lipoprotein) from oxidation.
Extra virgin olive oil biophenols inhibit cell-mediated oxidation of LDL by increasing the mRNA transcription of glutathione-related enzymes.
Researchers have observed that olive oil reduces the plasmatic concentration of molecules in the walls of blood vessels that promote inflammation. They attribute this beneficial effect of olive oil partly to the high presence of micronutrients that might have an effect similar to that of anti-inflammatory drugs.
* Cancer Prevention
Olive oil contains a vast range of substances such as monounsaturated free fatty acids (e.g., oleic acid), hydrocarbon squalene, tocopherols, aroma components, and phenolic compounds. Higher consumption of olive oil is considered the hallmark of the traditional Mediterranean diet, which has been associated with low incidence and prevalence of cancer, including colorectal cancer. The anti cancer properties of olive oil have been attributed to its high levels of monounsaturated fatty acids, squalene, tocopherols, and phenolic compounds.
The major phenolic compounds identified and quantified in olive oil belong to three different classes: simple phenols (hydroxytyrosol, tyrosol); secoiridoids (oleuropein, the aglycone of ligstroside, and their respective decarboxylated dialdehyde derivatives); and the lignans [(+)-1-acetoxypinoresinol and pinoresinol]. All three classes have potent antioxidant properties. High consumption of extra-virgin olive oils, which are particularly rich in these phenolic antioxidants (as well as squalene and oleic acid), should afford considerable protection against colon cancer, breast cancer, skin cancer, coronary heart disease, and ageing by inhibiting oxidative stress.
Helicobacter pylori is linked to a majority of peptic ulcers and to some types of gastric cancer, and resistance of the microorganism to antibiotic treatment is now found worldwide. In vitro tests have shown the phenolic compounds contained in Virgin olive oil to exert a strong bactericidal activity against eight strains of H. pylori, three of them resistant to some antibiotics. These results open the possibility of considering virgin olive oil a chemopreventive agent for peptic ulcer or gastric cancer, but this bioactivity should be confirmed in vivo in the future
*Non Alcoholic Fatty Liver Disease
Inappropriate dietary fat intake, excessive intake of soft drinks, insulin resistance and increased oxidative stress results in increased free fatty acid delivery to the liver and increased hepatic triglyceride accumulation. An olive oil-rich diet decreases accumulation of triglycerides in the liver, improves postprandial triglycerides, glucose and glucagon-like peptide-1 responses in insulin-resistant subjects, and upregulates glucose transporter-2 expression in the liver.