A grapefruit a day - particularly the red variety - can help keep heart disease at bay, according to a new study by Israeli researchers. In a controlled study group of patients with heart disease, the scientists found that feeding some patients the equivalent of one grapefruit daily significantly reduced levels of cholesterol in comparison to patients that did not eat grapefruit. Chronic high blood cholesterol is a major risk factor for heart disease.

The study, which strengthens a growing body of evidence supporting the heart-healthy benefits of eating citrus fruit, was published Feb. 3 on the website of the American Chemical Society’s Journal of Agricultural and Food Chemistry . The findings come at an appropriate time: The month of February has been designated as American Heart Month and heart disease is the number one killer of women in the United States. The study will appear in the journal’s March 22 print issue.

The study included 57 patients, both men and women, with hyperlipidemia (high blood cholesterol) who recently had coronary bypass surgery and whose high lipid levels failed to respond significantly to statin drugs.

Statins are commonly prescribed to lower cholesterol, according to study leader Shela Gorinstein, Ph.D., a chief scientist at the Hebrew University of Jerusalem.

The patients, equally divided into three treatment groups, were given either a single serving of fresh red grapefruit, white (blond) grapefruit or no grapefruit, along with regular, balanced meals for 30 consecutive days. Israeli Jaffa red and white grapefruit varieties, which are available in the U.S., were used in this study.

The patients who received either red or white grapefruit showed significant decreases in blood lipid levels, whereas the patients that did not eat grapefruit showed no changes in lipid levels, according to the researchers. Red grapefruit was more effective than white in lowering lipids, particularly blood triglycerides, a type of cholesterol whose elevated levels are often associated with heart problems, the researchers say.

It is likely that antioxidants in the grapefruits are responsible for their health benefits, says Gorinstein, adding that the red variety generally has higher antioxidants than the white. But it’s also possible that red grapefruit may contain unknown chemicals that are responsible for the observed triglyceride-lowering effect, she says. Additional studies are planned.

Both the fresh fruit and the juice are believed to be equally beneficial, Gorinstein and her associates say. One cup of fresh grapefruit is roughly equivalent to half a cup of juice.

Grapefruit is known to interact with certain medications -sometimes adversely - so the researchers caution people on prescription medication to consult with their doctor or pharmacist to determine whether their medicine will interact before consuming grapefruit products. Appropriate exercise, well-balanced nutrition and avoidance of tobacco also are important factors in reducing the risk of heart disease, health experts say.