By: Thomas Pickering, MD, DPhil, FRCP, Director of Integrative and Behavioral Cardiology Program
of the Cardiovascular Institute at Mount Sinai School of Medicine, New York.

We have recommended the DASH (Dietary Approaches to Stop Hypertension) diet as the ideal diet for people who have high blood pressure, because studies with it have shown that it can lower blood pressure more effectively than other diets, and also because it is the sort of diet that is likely to result in a low risk of heart disease and cancer.

A new analysis of the first DASH trial has looked to see how many of the patients who had high blood pressure (a pressure of 140/90 mmHg or higher) at the start of the study were able to reduce their pressure to normal levels as a result of the diet. (Some of the participants had pressures that were in the upper end of the normal range). The 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. As reported previously, 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).

The new finding is the numbers of participants whose blood pressure became normal during the study (that is less than 140/90 mmHg). With the DASH diet, 70 per cent were able to normalize their blood pressure, as compared to 45 per cent of those on the fruit and vegetable diet, and 23 per cent on the control diet.

Doctor’s comments

This publication presents the DASH study findings in a different fashion from the previous ones, that is in terms of the chances of being able to achieve a “normal” blood pressure as a result of eating the different diets. As the earlier publications have shown, the DASH combination diet was more effective than the fruit and vegetable diet (this is thought to be the result of the addition of calcium in the dairy products). The usual criterion for satisfactory blood pressure control is a reading of less than 140/90 mmHg, and this analysis showed that people with mild hypertension have a good chance of being able to get their pressure controlled without having to take medication. It should be pointed out, however, that these individuals had only minimally elevated pressures at the start of the study (the average value was 144/90 mmHg), so they didn’t have very far to go to achieve control.

Where it was published

PR Conlin and colleagues. The effect of dietary patterns on blood pressure control in hypertensives patients: results from the Dietary Approaches to Stop Hypertension (DASH) trial. American Journal of Hypertension 2000; 13:949.