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Back to Hypertension

The DASH Diet: What It Is and What the Research Says

Numerous studies have confirmed the beneficial role of the DASH dietary pattern on blood pressure, and various DASH-style diets have also been examined.

Highlights

  • The DASH diet is a dietary pattern that is similar to Canada’s Food Guide, with a greater emphasis placed on vegetables, fruit and milk products;
  • Adhering to the DASH diet can reduce the risk of developing hypertension;
  • There are several variations of the DASH diet, including one with high-fat dairy instead of low-fat dairy; these have shown benefits regarding other cardiovascular risk factors in addition to blood pressure.

The Dietary Approaches to Stop Hypertension (DASH) diet is recognized as a pattern of healthy eating that can effectively lower elevated blood pressure as well as reduce the risk of developing hypertension as indicated in several strong studies, including systematic reviews and meta-analyses of randomized controlled trials.1-3

Meta-analyses have also shown that the DASH diet is associated with a reduced risk of cardiovascular disease and type 2 diabetes.4-6

What is the DASH diet?

 The DASH diet is generally described as a dietary pattern that is similar to Canada’s Food Guide, with a greater emphasis placed on fruit and vegetables and milk products.

  • In general, the DASH diet consists of about 8 to 10 servings of fruit and vegetables and about 3 servings of milk products.

Various studies examining DASH-style diets have also been conducted. The table below presents a summary of the number of servings of fruit and vegetables and dairy products for some of the main trials investigating the DASH diet or DASH-style diets.

Study Comparison diets

Fruit and vegetables,

servings/d

Total dairy,

servings/d

Low-fat dairy,

servings/d

High-fat dairy, servings/d
Original DASH7 Control 4 1 0 0
Fruit and vegetables 9 0 0 0
DASH 10 3 2 1
OmniHeart8 DASH with higher carbohydrates 11 2 2 0
DASH with higher protein 9 3 3 0
DASH with higher unsaturated fat 11 2 2 0
Beef in an Optimal Lean Diet (BOLD)9 Healthy American 6 2 1 1
DASH 8 2 2 0
BOLD 8 2 2 0
BOLD plus additional protein 8 5 5 0
High-fat DASH10 Control 3 1 0 1
DASH 7 3 3 0
Higher-fat/lower-carb DASH 6 3 0 3

DASH-style diet trials

  • The original DASH trial included about 2 servings of low-fat dairy and about 1 serving of regular-fat dairy (cheese). In this study, the DASH diet reduced blood pressure twice as much as the diet high in fruit and vegetables only.7
  • In the OmniHeart trial, the effects of different variations of the DASH diet were compared. All diets had a favourable impact on cardiovascular risk factors. In addition, substitution of carbohydrates with protein and unsaturated fat, in the context of the DASH dietary pattern, led to further improvement in cardiovascular risk factors.8
  • The BOLD diet, a DASH-style diet that contained lean beef, improved blood lipids to a similar extent as the DASH diet.9
  • In another trial, a high-fat version of the DASH diet, which included high-fat dairy instead of low-fat dairy, was compared to the DASH diet. Both the DASH diet and its high-fat version decreased blood pressure to the same extent, but the high-fat diet also improved plasma triglycerides and VLDL concentrations without increasing LDL cholesterol.10

Conclusion

The DASH diet, which emphasizes fruit and vegetables and milk products, is beneficial to cardiovascular health and, in particular, to blood pressure reduction.

Different variations of the DASH diet have been examined. While the findings indicate that these DASH-style diets are cardioprotective, the extent of their beneficial impact on different cardiovascular risk factors varies.

Further investigation is needed with regard to the role of high-fat dairy as part of the DASH diet.

References

  1. Eckel RH et al. 2013 AHA/ACC guideline on lifestyle management to reduce cardiovascular risk: a report of the American College of Cardiology/American Heart Association Task Force on Practice Guidelines. J Am Coll Cardiol 2014;63:2960-2984.
  2. Saneei P et al. Influence of Dietary Approaches to Stop Hypertension (DASH) diet on blood pressure: a systematic review and meta-analysis on randomized controlled trials. Nutr Metab Cardiovasc Dis 2014;24:1253-1261.
  3. Gay HC et al. Effects of different dietary interventions on blood pressure: systematic review and meta-analysis of randomized controlled trials. Hypertension 2016;67:733-739.
  4. Salehi-Abargouei A et al. Effects of Dietary Approaches to Stop Hypertension (DASH)-style diet on fatal or nonfatal cardiovascular diseases—incidence: a systematic review and meta-analysis on observational prospective studies. Nutrition 2013;29:611-618.
  5. Siervo M et al. Effects of the Dietary Approach to Stop Hypertension (DASH) diet on cardiovascular risk factors: a systematic review and meta-analysis. Br J Nutr 2015;113:1-15.
  6. Shirani F et al. Effects of Dietary Approaches to Stop Hypertension (DASH) diet on some risk for developing type 2 diabetes: a systematic review and meta-analysis on controlled clinical trials. Nutrition 2013;29:939-947.
  7. Appel LJ et al. A clinical trial of the effects of dietary patterns on blood pressure. N Eng J Med 1997;336:1117-1124.
  8. Swain JF et al. Characteristics of the diet patterns tested in the optimal macronutrient intake trial to prevent heart disease (OmniHeart): options for a heart-healthy diet. J Am Diet Assoc 2008;108:257-265.
  9. Roussell MA et al. Beef in an Optimal Lean Diet study: effects on lipids, lipoproteins, and apolipoproteins. Am J Clin Nutr 2012;95:9-16.
  10. Chiu S et al. Comparison of the DASH (Dietary Approaches to Stop Hypertension) diet and a higher-fat DASH diet on blood pressure and lipids and lipoproteins: a randomized controlled trial. Am J Clin Nutr 2016;103:341-347.

Keywords: hypertension , dash diet


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