Researchers may have discovered one of the secrets of the Mediterranean diet: olive oil! The scientific community agrees that olive oil, high in monounsaturated fatty acids (MUFA) and antioxidants, helps reduce levels of total and LDL cholesterol thereby reducing risk of cardiovascular disease. And a new study shows that a diet high in MUFA from olive oil can also help reduce blood pressure levels.
Diet and blood pressure
Researchers have known for some time that the characteristics of a Mediterranean-type diet are important in controlling blood pressure levels. These characteristics include:
- high fiber intake,
- high fruit and vegetable intake,
- high MUFA and low saturated fat intake and,
- low sodium and high potassium, magnesium and calcium intake.
It may be that one or a combination of these factors helps decrease blood pressure levels. And since high blood pressure is a risk factor for stroke, the third leading causes of death in the United States, olive oil may reduce the incidence of stroke.
MUFA vs. PUFA
Ferrara and his colleagues designed a study to look at the effects of a diet high in monounsaturated fatty acids vs. diets high in polyunsaturated fatty acids (PUFA). Twenty-three people with mild to moderate hypertension (10 males and 13 females, ages 25-70 years) were randomly assigned to either a diet high in MUFA using extra-virgin olive oil, or high in polyunsaturated fatty acids using sunflower oil for six months. Both diets contained less total and saturated fat than the subjects’ usual diets. Their usual diets contained 34% total fat and 11% saturated fat, while the study diets contained 26% total fat and 6% saturated fat. After the initial six-month study period, the groups switched to the other type of diet. Both types of diets contained similar amounts of calories, saturated fat, cholesterol, fiber and minerals (sodium, potassium, magnesium and calcium). The only significant difference in the two study diets was the amount of MUFA vs. PUFA.
Ferrara and his colleagues found that while on the extra-virgin olive oil diet, subjects reduced the amount of antihypertensive medication necessary to control blood pressure levels by 48%, vs. only a 4% reduction on the sunflower oil diet. In addition, eight subjects on the extra-virgin olive oil diet required no antihypertensive medications; all subjects on the sunflower oil diet required antihypertensive medication. The authors conclude that a diet lower in total fat and saturated fat that contains higher amounts of MUFA can lower blood pressure levels and reduce or eliminate the need for medications in people with hypertension.
Possible role of olive oil in reducing blood pressure
So why does olive oil lower blood pressure? One possible reason is its polyphenol content. Polyphenols are potent antioxidants which help arteries dilate, thereby reducing blood pressure. Ten grams of extra-virgin olive oil contains five mg of polyphenols; sunflower oil has no polyphenols.
Our recommendations
There are numerous health benefits to replacing saturated and polyunsaturated fatty acids with monounsaturated fatty acids such as olive and canola oil. Switching from polyunsaturated oils such as sunflower, safflower, soybean, and corn to oils high in monounsaturated fatty acids such as olive oil and canola oil leads to decreased risk of stroke by lowering blood pressure levels; and also helps decrease risk of heart attack by lowering total and LDL cholesterol levels. Use olive or canola oil in cooking or salad dressings, and look for margarine-like spreads based on olive or canola oil to use on toast, vegetables, and potatoes to reap the heart-healthy benefits.
Remember that while replacing saturated fats with MUFAs is a step towards improved heart health, moderation remains important. Also, if you follow a very low fat diet and still have high blood pressure, consider adding one to three tablespoons of olive oil to your daily food choices and monitor your blood pressure for any changes.