A diet high in fruits, vegetables, low-fat dairy products and other low-fat foods significantly and quickly lowers blood pressure, according to a multicenter study that includes Johns Hopkins.
The results suggest that the diet, when added to other "heart-healthy" habits, may prevent high blood pressure and reduce the need for high blood pressure medication in people with hypertension, the researchers say. Fifty million U.S. residents have high blood pressure, while the general population is at high risk for developing hypertension in part because of poor eating habits.
The study, which was funded by the National Heart, Lung and Blood Institute, will be presented Nov. 13 at the American Heart Association's 69th annual Scientific Sessions in New Orleans.
"It's already known that three dietary factors -- salt, body weight and alcohol -- affect blood pressure, but our findings are important because they identify a fourth factor: the pattern of food we eat," says Lawrence Appel, M.D., the study's principal investigator at Hopkins and an associate professor of medicine.
The Dietary Approaches to Stop Hypertension (DASH) study included 459 adults with systolic blood pressure 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 of individual nutrients.
Participants ate one of three diets for eight weeks: a typical American diet high in fat and low in fruits and vegetables; a diet high in fruits and vegetables; or a combination diet low in total fat, saturated fat and cholesterol and high in fruits, vegetables and low-fat dairy products, which are high in fiber, protein, potassium, magnesium and calcium.
Among all participants, the combination diet reduced systolic blood pressure by an average of 5.5 mm Hg and diastolic pressure by an average of 3.0 mm Hg. The diet high in fruits and vegetables also reduced blood pressure, but to a smaller extent. The reductions occurred within two weeks of the start of the study.
Among those with hypertension, the combination diet reduced systolic blood pressure by an average of 11.4 mm Hg and diastolic pressure by an average of 5.5 mm Hg. The reductions were similar to those achieved with blood pressure medication.
About 50 percent of participants were women and 60 percent were African-Americans, who suffer from hypertension earlier and more often than whites. The diet was tested without changes in weight, salt intake and alcohol consumption.
The DASH combination diet provided nine to 10 daily servings of fruits and vegetables (about twice the current amount in Americans' diets) and three daily servings of low-fat dairy products (about double the current amount).
Other centers in the study were the Pennington Biomedical Research Center, Brigham and Women's Hospital, Harvard Medical School, Duke University Medical Center and the Kaiser Permanente Center for health Research.
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