Healthy blood pressure levels are an indicator of how clear the body’s arteries are. When blood pressure levels get out of balance, they can signal a potential heart attack or stroke. High blood pressure levels are often caused by atherosclerosis, also called hardening of the arteries, which occurs when oxidized particles of LDL cholesterol stick to the walls of the arteries. Eventually these particles build up and form plaque, narrowing the blood vessels and putting a heavier workload on the heart as it pumps oxygenated blood to the entire body.

One of the specific compounds in olive oil that directly combats this build-up is called oleuropein. Oleuropein has been found by scientists to prevent the LDL cholesterol from oxidizing and sticking to the arterial walls.

Saturated fat diets are associated with higher blood pressure but there have been few good studies on whether the reverse is true; can unsaturated fats lower blood pressure? And are some unsaturated fats better than others? The answer is yes according to a well-designed study published by researchers from the University of Naples, Italy. They fed 23 subjects a diet rich either in monounsaturated fatty acids (MUFA) (olive oil) or polyunsaturated fatty acids (PUFA) (sunflower oil) for one year. In their words, "the main result of our investigation was a straightforward reduction in antihypertensive tablet consumption when patients were given olive oil, whereas drug consumption was only mildly affected by sunflower oil." The need for common blood pressure drugs such as atenolol, HCTZ, and nifedipine was cut in half after just 4 months on the olive oil diet whereas drug consumption was only mildly affected by sunflower oil. Cholesterol and triglyceride levels were also slightly lower while on the olive oil diet. There are as many as 5 mg of antioxidant polyphenols (absent in sunflower oil) in every 10 grams of olive oil. Polyphenols have been shown to reduce coronary artery disease and may be the substance lowering blood pressure. Antioxidants reduce nitric acid levels, a substance in the body known to raise blood pressure. At 26.6% of calories from fat the experimental diet was also low in total fat. The study was double blinded with neither subjects nor researchers aware of which oil was being used. Subjects were told to cook with given oil and men were told to add 40g and women to add 30g of oil after cooking. The study participants experienced no change in weight during the year. For readers with high blood pressure thinking of doing their own olive oil study: please get the consent of your doctor before changing medication doses.

SOURCES

From the Departments of Clinical and Experimental Medicine (Drs Ferrara, Raimondi, Guida, and Marotta, and Ms d'Episcopo) and Biochemistry and Medical Biotechnologies (Mr Dello Russo), Federico II University of Naples, Naples, Italy.

Reprints: L. Aldo Ferrara, MD, Department of Clinical and Experimental Medicine, Federico II University of Naples, Via S Pansini 5, 80131, Naples, Italy.