March 29, 2000 (Baltimore) -- People on high blood pressure medications may be able to reduce the amount of medicine they take if they substitute extra-virgin olive oil for other types of fats in their diet, a study in the March 27 issue of the journal Archives of Internal Medicine reports.
"The most important finding in this study is that the daily use of olive oil, about 40 grams per day, markedly reduces the dosage of [blood pressure medication] by about 50% in hypertensive patients on a previously stable drug dosage," says L. Aldo Ferrara, MD, associate professor of internal medicine at the Frederico II University of Naples in Naples, Italy, and the study's lead author.
Forty grams per day of extra-virgin olive oil amounts to about four tablespoons, Ferrara tells WebMD. That is the amount men in this study consumed, with women consuming about three tablespoons. Each study participant had high blood pressure and was on medicine to control it. Each ate a diet comprised of 17% protein, 57% carbohydrates, 35 grams of fiber, and 26% total fats with 5.8% saturated fats, per day for six months. Participants were assigned to receive the majority of their fats from either extra virgin olive oil or sunflower oil. Then each participant was switched to the other type of oil for an additional six months.
During the 12-month study, regular measurements of blood pressure were taken, and when blood pressure fell, the dose of blood pressure medication was reduced.
"Daily dosage of [blood pressure medication] was reduced by 48% during the olive oil diet and by 4% during the sunflower oil diet," reports Ferrara. "In particular, blood pressure was controlled without any medication in eight patients during the olive oil diet but none during the sunflower oil diet.
Ferrara explains that only extra-virgin olive oil contains antioxidants called "polyphenols," which he and his fellow researchers think may be responsible for the drop in blood pressure seen in this study. Polyphenols are completely absent from sunflower oil, according to Ferrara and colleagues.
Alice Lichtenstein, DSc, professor of nutrition at the Jean Mayer U.S. Department of Agriculture Human Nutrition Research Center on Aging at Tufts University, reviewed the study for WebMD. "This is an interesting finding, but there are lots of interesting findings," she tells WebMD. "I'm not aware of a relationship between polyphenols and [high blood pressure], and from a public health perspective I'm not sure it has much utility. I just saw a study recently where a diet containing 600 calories of chocolate a day had health benefits the authors are also attributing to the polyphenols in chocolate. But does this mean we should all be consuming 600 calories a day of chocolate or 40 grams a day of extra-virgin olive oil? This study needs to be followed up, and I hope that no one reduces their [blood pressure] medicines and starts consuming extra-virgin olive oil based on this one study."
Lichtenstein also cautions that not all extra-virgin olive oils are the same, and that more complete characterization of exactly what is in each brand of oil also needs to be done before its health benefits can be assured.
Patricia Darragh, a spokeswoman for the California Olive Oil Council, says council members have heard anecdotal reports of a beneficial effect of olive oil on blood pressure. "I believe there are studies underway, but we're not including this in our educational materials yet," she tells WebMD. "We do support the findings of an American Heart Association study comparing rates of cardiovascular disease and types of fats consumed around the world suggesting that consumption of olive oil has clear health benefits. Olive oil still has calories, of course, so substitution for other types of fats is necessary."
- Patients with high blood pressure who substitute extra-virgin olive oil in their diets for other types of fat can reduce the amount of medication they need by half, according to a new study.
- Researchers suspect that substances in extra-virgin olive oil known as antioxidant polyphenols are responsible for the reduction of blood pressure in these patients.
- One expert cautions that these results need to be followed up with more research before advising patients to consume 40 grams per day of extra-virgin olive oil.