The DASH (Dietary Approaches to Stop Hypertension) diet was designed to provide a palatable diet that would be good for general health and lower the blood pressure. It contains a lot of potassium, magnesium, and calcium, minerals that have been shown to lower blood pressure. The potassium and magnesium are provided by fruits and vegetables, and the calcium by low-fat dairy products. The diet was first tested in a very tightly controlled study sponsored by the National Institutes of Health in which participants were fed one of three diets for an 8-week period. The first was a "control" diet, equivalent to the average American diet; the second was a diet rich in fruits, grains, and vegetables, and the third was the "DASH" diet, which was similar to the fruit and vegetable diet but with the addition of low-fat dairy products. Salt intake was not reduced in any of the diets. The combination DASH diet produced the greatest reduction of blood pressure (11 mmHg systolic and 6 mmHg diastolic). The fruit and vegetable diet also lowered blood pressure (by 7 mmHg systolic and 3 mmHg diastolic). African-Americans showed a bigger response than whites.

A second DASH study examined the effects of varying the salt content of the diet. There were 412 patients with blood pressure in the "high normal" or mildly hypertensive range, who were randomly allocated to eat either a regular American diet or the DASH diet for 3 months. This was done by providing them with specially prepared meals. For each one of the 3 months the salt content was varied; the "high"-salt diet had 143 milliequivalents of sodium (3.3 grams), which is the same amount as the typical American diet; the "medium"-salt diet had 106 milliequivalents (3.3 grams), and the "low"-salt diet had 65 milliequivalents (1.5 grams).

While eating the regular US diet, the effect of salt restriction was to lower systolic pressure by 2.1 mmHg on going from the high to the medium salt intake, and by a further 4.6 mmHg on going from the medium to the low salt intake. Thus the effect of going from a high to a low salt intake was 6.7 mmHg. While on the DASH diet the same changes were seen, although not quite as much (4.0 instead of 6.7 mmHg). For people with mild hypertension, the reduction of blood pressure achieved by the combination of the DASH and low-salt diet was 11.5/5/7 mmHg, which is equivalent to the changes seen with blood pressure-lowering medications.