What Is the DASH Diet?

Even slight elevations of blood pressure above the optimal level of less than 120/80 mm Hg are unhealthy. The higher above normal the blood pressure, the greater the health risk.

In the past, researchers tested various single nutrients -- such as calcium and magnesium -- to find clues about what affects blood pressure. These studies were done mostly with dietary supplements, and their findings were not conclusive.

Then, scientists supported by the National Heart, Lung, and Blood Institute (NHLBI) tested nutrients as they occur together in food. The results were dramatic. The clinical study, called "DASH" (Dietary Approaches to Stop Hypertension) found that elevated blood pressure can be reduced with an eating plan low in saturated fat, total fat and cholesterol, and rich in fruits, vegetables and lowfat dairy foods.

The plan is rich in magnesium, potassium, and calcium, as well as protein and fiber.

DASH research involved 459 adults with systolic blood pressures of less than 160 mm Hg and diastolic pressures of 80 to 95 mm Hg. About half of the participants were women and 60% were African Americans.

DASH compared three eating plans:

• A plan similar in nutrients to what many Americans consume
• A plan similar to what Americans consume, but higher in fruits and vegetables
• A "combination" plan (the DASH diet)

All three plans used about 3,000 milligrams of sodium daily -- about 20% below the U.S. average for adults. None of the plans was vegetarian or used specialty foods.

Results showed that both the fruit/vegetable and combination plans reduced blood pressure, but the combination plan had the greatest effect. The DASH eating plan reduced blood pressure by an average of about 6 mm Hg for systolic and 3 mm Hg for diastolic. It worked even better for those with high blood pressure -- the systolic dropped on average about 11 mm Hg, and the diastolic about 6 mm Hg. Further, the reductions came within just 2 weeks of starting the eating plan.