Benefits in addition to salt restriction
4-3 A CLINICAL TRIAL OF THE EFFECTS OF DIETARY PATTERNS ON BLOOD PRESSURE
Current national guidelines recommend non-pharmacological approaches to lower BP—weight control, reduced salt intake, reduced alcohol consumption, and possibly increased potassium intake. Other dietary factors may influence BP. Vegetarians tend to have lower BP than non-vegetarians. Aspects of vegetarian diets believed to reduce BP include high levels of fiber, high potassium and magnesium, and reduced fat content.
This trial— "Dietary Approaches to Stop Hypertension (DASH)" tested the combined effects of nutrients that occur together in food.
Conclusion: Diet high in fruit and vegetables and low in fat can substantially reduce BP.

STUDY

1. Enrolled over 450 adults with systolic BP less than 160 and diastolic BP 80-95.
2. For 3 weeks all subjects were fed a control diet low in fruits, vegetables, and dairy products. The fat content was typical of the average US diet.
3. After 3 weeks, randomized for 8 weeks to: 1) continue the control diet, or 2) a diet rich in fruits and vegetables, or 3) a combination diet rich in fruits vegetables, with low-fat dairy products (reduced total and saturated fat).
4. Sodium intake and weight were maintained at constant levels.

RESULTS

1. At baseline, the mean BP was 131/85.
2. The high fruit and vegetable diet reduced BP by 2.8/1.1 compared to control diet.
3. The combination diet reduced BP by 5.5/3.0 mm Hg compared with the control diet.
4. Among 133 subjects with hypertension (> 140/90) the combination diet reduced BP by 11.4/5.5 compared with the control diet.
5. Urinary potassium and magnesium increased in the combination group.
6. The reductions in BP were achieved after 2 weeks and were sustained.

DISCUSSION

1. Dietary patterns can favorable affect BP in adults with average BP of less than 160 systolic BP and diastolic BP 80-95.
2. The favorable effect was not due to changes in salt intake, body weight, or alcohol intake.
3. The results of this study should be broadly applicable to the US population. (The subjects were demographically heterogeneous.)
4. The 8 to 10 servings of fruits and vegetables were about twice that consumed by the general US population. The low-fat dairy products consumed in the combination diet were about 2 times greater than the US average.
5. The study was not designed to assess long-term compliance or effects on BP.
6. The combination diet might be an effective nutritional approach to preventing hypertension.
7. The combination diet should complement, rather than supplant, the current recommendations to reduce salt intake, control weight, and reduce alcohol intake.
8. The reduction in BP was similar to that achieved by drug monotherapy for mild hypertension.
9. Adoption of the diet could potentially shift the population distribution of BP downward, reducing incident stroke and coronary heart disease.

CONCLUSION
A diet rich in fruits, vegetables and low-fat dairy products can substantially reduce BP. This diet offers an additional nutritional approach to preventing and treating hypertension.
NEJM April 17, 1997; 336: 1117-24 Original trial from The DASH Collaborative Research Group, first author from Johns Hopkins University, Baltimore, MD

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