Objectives

The objective of the Dietary Approaches to Stop Hypertension (DASH) study was to test the effects of dietary patterns characterized by high intakes of certain minerals and fiber associated with low blood pressure compared with each other and with a control dietary pattern relatively low in potassium, magnesium, calcium, and fiber, and has a fat and protein profile mirroring current US consumption.

Background

High blood pressure affects almost 5 million people in the United States and places them at a high risk for cardiovascular disease. High blood pressure is characterized as a systolic blood pressure of 140 mm Hg or higher or diastolic blood pressure of 90 mm Hg, or higher, or the need for antihypertensive medication. The risk of cardiovascular disease increases progressively throughout the entire range of blood pressure levels, thus blood pressure affects the health of many, including those that are not defined as hypertensive. The DASH aims to help prevent this highly prevalent public health problem.

Subjects

The study consisted of 459 healthy free-living adult men and women, 22 years or older, who have a diastolic blood pressure of 80 to 95 mm Hg and a systolic blood pressure less than 160 mm Hg. Since there is a disproportionate burden of hypertensions and its complications in minority populations, and particularly among African Americans, two-thirds of DASH participants are from a minority background.

Design

The Dietary Approaches to Stop Hypertension multicenter, randomized, controlled-feeding trial examined the impact of dietary patterns on blood pressure in 459 adults with blood pressure <160 mm Hg systolic and 80 to 95 mm Hg diastolic. After a 3-week run-in period on a control diet low in fruits, vegetables, and dairy products, and with a fat content typical for Americans, participants were randomized for 8 weeks to either the control diet, a diet rich in fruits and vegetables, or a combination diet that emphasized fruits, vegetables, and low-fat dairy products. Body weight and sodium intake were held constant, and physical activity did not change during the intervention.

Conclusions

This trial demonstrated that certain dietary patterns can favorably affect blood pressure in adults with average systolic blood pressures of less than 160 mm Hg and diastolic blood pressures of 80 to 95 mm Hg. Specifically, a diet rich in fruits, vegetables, and low-fat dairy products and with reduced saturated and total fat lowered systolic blood pressure by 5.5 mm Hg and diastolic blood pressure by 3.0 mm Hg more than a control diet. A diet rich in fruits and vegetables also reduced blood pressure, but to a lesser extent. The gradient of blood-pressure reduction across diets indicates that some aspects of the fruits-and-vegetables diet reduced blood pressure and that additional aspects of the combination diet reduced it further. In conclusion, a diet rich in fruits, vegetables, and low-fat dairy foods and with reduced saturated and total fat can substantially lower blood pressure. Such a diet offers an additional nutritional approach to the prevention and treatment of hypertension.

Publications

Bray, GA, for the DASH Collaborative Group, "The Effect of Dietary Patterns on Blood Pressure: Results From the Dietary Approaches to Stop Hypertension (DASH) Clinical Trial." Current Concepts in Hypertension, November, 1998, 4-5.

Sacks FM, Obarzanek E, Windhauser M, Svetkey LP, Vollmer WM, McCullough M, Karanja N, P Lin, Steele P, Proschan M, Evans MA, Appel L, Bray GA, Vogt TM, Moore TJ, for the DASH Investigators. Rationale and Design of the Dietary Approaches to Stop Hypertension Trial (DASH). A multicenter controlled-feeding study of dietary patterns. Ann Epidemiol. 1995; 5:108-117.

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