Introduction to DASH Diet

The DASH eating plan follows heart healthy guidelines to limit saturated fat and cholesterol. It focuses on increasing intake of foods rich in nutrients that are expected to lower blood pressure, mainly minerals (like potassium, calcium, and magnesium), protein, and fiber. It includes nutrient-rich foods so that it meets other nutrient requirements as recommended by the Institute of Medicine.
The first DASH study involved 459 adults with systolic blood pressures of less than 160 mmHg and diastolic pressures of 80-95 mmHg.
 About 27 percent of the participants had high blood pressure. About 50 percent were women and 60 percent were African Americans. It compared three eating plans: a plan that includes foods similar to what many Americans regularly eat; a plan that includes foods similar to what many Americans regularly eat plus more fruits and vegetables; and the DASH eating plan. 
All three plans included about 3,000 milligrams of sodium daily. None of the plans was vegetarian or used specialty foods.
Results were dramatic. Participants who followed both the plan that included more fruits and vegetables and the DASH eating plan had reduced blood pressure. But the DASH eating plan had the greatest effect, especially for those with high blood pressure. 
Furthermore, the blood pressure reductions came fast—within 2 weeks of starting the plan.
The second DASH study looked at the effect on blood pressure of a reduced dietary sodium intake as participants followed either the DASH eating plan or an eating plan typical of what many Americans consume. This second study involved 412 participants. 
Participants were randomly assigned to one of the two eating plans and then followed for a month at each of the three sodium levels. The three sodium levels were a higher intake of about 3,300 milligrams per day (the level consumed by many Americans), an intermediate intake of about 2,300 milligrams per day, and a lower intake of about 1,500 milligrams per day.