Apr. 17, 1997 American mothers' often-ignored advice to eat fruits and vegetables, not cheeseburgers and doughnuts, now appears to substatially and quickly lower blood pressure, according to results of a study performed at Johns Hopkins and several other centers.
The findings offer more evidence that healthy diets can reduce the risk of heart disease and stroke, the nation's first- and third-leading killers, respectively. About 40 million Americans have high blood pressure, which is particularly common among people over 50 and a major risk factor for cardiovascular disease and stroke.
Results of the study, supported by the National Heart, Lung and Blood Institute, are published in the April 17 issue of The New England Journal of Medicine.
"We already know that weight control and reduced salt and alcohol intake are important steps to prevent and treat hypertension," says Lawrence Appel, M.D., lead author and an associate professor of medicine at Hopkins. "Our findings show that a diet rich in fruits, vegetables and low-fat dairy products and reduced in saturated and total fat offers an additional nutritional approach."
The Dietary Approaches to Stop Hypertension (DASH) study included 459 adults with high-normal or stage 1-mild hypertension (systolic blood press of less than 160 mm Hg and diastolic pressure of 80-95 mm Hg). Researchers examined the impact on blood pressure of whole dietary patterns rather than individual nutrients or supplements.
Participants ate one of three diets for eight weeks: a control diet low in fruits, vegetables and dairy products and with a fat content typical of the American diet; a diet high in fruits and vegetables; or a "combination" diet low in saturated and total fat and high in fruits, vegetables and low-fat dairy products.
Among the 133 participants with high blood pressure, the combination diet reduced systolic and diastolic blood pressure by an average of 11.4 mm Hg and 5.5 mm Hg, respectively. Systolic blood pressure, the higher of the two numbers, occurs when the heart is contracting; diastolic blood pressure occurs when the heart relaxes between contractions.
"These blood-pressure reductions are clinically important because they are similar to those reductions commonly achieved through use of one anti-hypertensive medication," Appel says.
Among the 326 participants with high-normal blood pressure, the combination diet reduced systolic and diastolic blood pressure by an average of 3.5 mm Hg and 2.1 mm Hg, respectively.
"These reductions are important from a public health perspective because they may prevent hypertension from occurring," says Appel.
Among all participants, the diet high in fruits and vegetables reduced blood pressure, but to a lesser extent than the combination diet. The reductions occurred within two weeks of the start of the study. The blood pressure reductions were independent of body weight, salt intake and alcohol consumption, which were held constant.
The DASH combination diet provided nine to 10 daily servings of fruits and vegetables (about twice the usual amount in Americans' diets) and three daily servings of low-fat dairy products (about double the usual amount in Americans' diets). More information about the DASH diet is available on the World Wide Web at http://dash.bwh.harvard.edu
Other investigators and institutions in the study were Thomas J. Moore, M.D., at Brigham and Women's Hospital, Thomas M. Vogt, M.D., at Kaiser Permanente Center for Health Research, Laura P. Svetkey, M.D., at Duke University Medical Center, George A. Bray, M.D., at the Pennington Biomedical Research Center, and Eva Obarzanek at the National Heart, Lung and Blood Institute.
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