A diet low in fat and rich in fruits and vegetables has been found for the first time to lower blood pressure quickly and as effectively as drugs, a new multicenter study has shown.
The researchers said that many people who now must take medication to control their blood pressure could do so with the diet and without the drugs, which have unwanted side effects.
Americans spend billions of dollars a year on blood pressure medications, said Dr. Edward Rocella, a hypertension specialist at the National Heart, Lung and Blood Institute.
The new study, described yesterday at the annual meeting of the American Heart Association in New Orleans, suggests that ''one diet may do it all'' -- help prevent high blood pressure, heart disease and many cancers, said Dr. Denise Simons-Morton, leader of the Prevention Scientific Research Group at the heart institute, one of the study's sponsors.
The new study tested the effects of dietary changes in 459 adults at six medical centers. All had systolic blood pressures (the pressure when the heart beats) of less than 160 millimeters of mercury and diastolic pressures (the pressure when the heart rests) of 80 to 95 millimeters. About half were women, and nearly 60 percent were blacks, who have a higher rate of hypertension than whites. High blood pressure was defined as a pressure of 140 over 90 or higher.
Participants were randomly divided into three groups. One ate a diet similar to what the average American adult now eats. A second group's diet was high in fruits and vegetables, with all other items remaining the same. The third group got a ''combination'' diet low in total fat, saturated fat and cholesterol but high in fruits, vegetables and low-fat dairy products. Total fats made up 27 percent of the participants' daily calories and saturated fats 6 percent, whereas in the average American diet fat makes up 34 percent of calories, with about 13 percent from saturated fats. All three diets contained a moderate amount of sodium and alcohol.
The combination diet worked best. It reduced systolic blood pressure within two weeks by an average of 5.5 millimeters and diastolic pressure by an average of 3 millimeters of mercury. The diet that was high in just fruits and vegetables also proved beneficial, but less so. It reduced systolic pressures by an average of 2.8 millimeters and diastolic by 1.1 millimeters. Both reductions were medically significant.
For those participants with hypertension, the combination diet was especially effective, lowering systolic pressure by 11.4 millimeters and diastolic by 5.5 millimeters, which is as good or better than reductions achieved with medication.
Dr. Simon-Morton said the amount of fruits and vegetables in the two diets -- nine to 10 standard servings -- could actually be achieved by eating two American-sized portions at each of three meals and one fruit or vegetable as a snack each day. Fruits, vegetables and dairy products are rich in nutrients like potassium, magnesium and calcium that other studies have indicated can have a beneficial effect on blood pressure.
The study was conducted at Johns Hopkins University in Baltimore, the Pennington Biomedical Research Center in Baton Rouge, La., Brigham and Women's Hospital and Harvard Medical School in Boston, and Duke University Medical Center in Durham, N.C., with the Kaiser Permanente Center for Health Research in Portland, Ore., serving as coordinator.