July 06, 2000
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 monosaturated 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." 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 40 g (about 4 spoonfuls) and women to add 30 g (about 3 spoonfuls) 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 participation of your doctor before changing medication doses.
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 (e-mail: firstname.lastname@example.org).