By: Thomas Pickering, MD, DPhil, FRCP, Director of Integrative and Behavioral Cardiology Program
of the Cardiovascular Institute at Mount Sinai School of Medicine, New York.

Olive oil is widely advocated as being good for preventing heart disease, but has not hitherto been associated with blood pressure reduction. An Italian study now suggests that it may lower blood pressure.

The study took 23 patients with moderate hypertension who were being treated with blood pressure-lowering drugs and monitored their blood pressures in three situations: first, while on their usual diet, which had 34% of its calories from fat and 11% from saturated fat (similar to an American diet); second, for six months on a diet where some of the saturated fat was replaced by extra-virgin olive oil, which is a mono-unsaturated fat (MUFA), in an amount of four tablespoons a day; and third, for six months on a diet where the saturated fat was partly replaced by sunflower oil, which is a poly-unsaturated fat (PUFA).

Over the 12 months of the study, the blood pressure was measured regularly, and if it fell by 5 mmHg or more, the blood pressure medications were reduced. The main finding was that the olive oil diet resulted in a reduction of blood pressure medications by 48%, while the sunflower oil reduced them by only 4%. The blood pressure was 135/90 at the end of the sunflower oil diet and 127/84 after the olive oil diet. The total cholesterol and triglycerides were also slightly lower after the olive oil diet.

Doctor’s comments

The rationale for this study is that the Mediterranean diet, which is rich in MUFA derived from olive oil, is generally associated with a low blood pressure, but no previous study has systematically examined the effects of olive oil on blood pressure. The mechanism by which olive oil lowers pressure is not known. The authors suggested that one component might be polyphenols, which are present in extra-virgin olive oil, and which are antioxidants. It is not known whether they affect blood pressure, however. Whether the same blood pressure lowering effect would be seen with ordinary olive oil is not clear from this study. The main message is that olive oil appears to be the best source of fat for people concerned about their health, and that it may help to keep the blood pressure down as well as preventing heart disease.

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