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What is the DASH Diet?

For the most part, the DASH Diet is an American application of the Mediterranean diet. The research in the 1970s and 1980s about Mediterranean diet laid the foundation for great quality nutrition research in the 1990s. The result was a large scale, multi-center trial of 459 adults age 22 years or older.¹

The goal of the research was to look at how diet might influence blood pressure. Participants had systolic blood pressures less than 160 and diastolic pressure between 80 to 95. A total of 29% carried a diagnosis of hypertension.

None of those in the study was taking high blood pressure medications,

50% female and 60% African Americans (who have much higher rates of high blood pressure). 27% were smokers. They were divided into three groups:

1. The control group was given a diet similar to what many Americans consumed at the time, although it was lower in potassium, magnesium, and calcium.
2. The second group was similar to the control but were given more fruits and vegetables
3. The third group was the DASH diet. This table outlines the diet.

The results were pretty fantastic:

• DASH diet lowered systolic blood pressure by an average of 6 mm Hg
• DASH diet lowered diastolic pressure by about 3 mm Hg.
• The Fruit and vegetable diet also lowered blood pressure about 3 mm Hg systolic and 2 mm Hg diastolic.
• Those with stage 1 hypertension (blood pressure 140/90-159/99 mm Hg):
  • DASH diet reduced systolic blood pressure by an average of 11 mm Hg
  • DASH diet reduced diastolic blood pressure by 6 mm Hg
• The lower blood pressures were seen within 2 weeks of starting the diets.

We have two considerations when talking about diet and nutrition. One is weight loss and that is, for the most part, about the number of calories consumed vs. those burned (calories in < calories out = weight loss). The other half of the dialogue is about the quality of those calories. Note the similarity to Mediterranean diet in the DASH Diet study. More whole grains, vegetables, fruits, nuts, seeds, dried beans, low-fat dairy, lean meats (and less meat) and quality fats.

The interesting thing was that people didn’t lose much weight (that wasn’t the goal of the study), but as you can see they had a dramatic improvement in their blood pressures. We see these same sorts of results when looking at Mediterranean style diet.

1. Appel LJ, Moore TJ, Obarzanek E, et al. A clinical trial of the effects of dietary patterns on blood pressure. DASH Collaborative Research Group. N Engl J Med 1997; 336:1117-1124.