What is the DASH (Dietary Approaches to Stop Hypertension) diet for adults with hypertension and diabetes?

What is the DASH Diet?

The DASH (Dietary Approaches to Stop Hypertension) diet is an evidence-based eating pattern specifically designed to lower blood pressure through increased consumption of fruits, vegetables, whole grains, and low-fat dairy products while reducing saturated fat, total fat, and sodium intake. 1

Core Components of the DASH Diet

The DASH dietary pattern consists of specific daily servings across food groups 1, 2:

• Fruits and vegetables: 8-10 servings per day 2, 3
• Low-fat dairy products: 2-3 servings per day 1, 2, 3
• Whole grains: Emphasized as primary carbohydrate source 1
• Lean proteins: Fish, poultry, and nuts preferred over red meat 1, 4
• Reduced fats: Saturated fat limited to <7-10% of total calories, with minimized trans-fatty acids 5, 3
• Limited sweets and sugar-containing beverages: Substantially reduced compared to typical American diet 1, 4

Nutritional Characteristics

The DASH diet is intentionally designed to be rich in specific micronutrients that influence blood pressure 1:

• High in potassium, magnesium, and calcium through natural food sources 1
• High in protein and fiber compared to typical Western diets 1
• Low in cholesterol (target <200 mg per day) 3
• Sodium restriction: Optimal goal <1,500 mg/day, with minimum reduction of 1,000 mg/day 1

Blood Pressure Lowering Effects

The ACC/AHA guidelines establish the DASH diet as the most effective dietary intervention for blood pressure reduction 1:

• In hypertensive adults: Reduces systolic BP by approximately 11 mm Hg and diastolic BP by 3 mm Hg 1
• In nonhypertensive adults: Reduces systolic BP by approximately 3 mm Hg 1
• Particularly effective in Black patients: Shows enhanced BP-lowering effects in this population 1
• Effects appear within 2 weeks of dietary adoption 6, 7

The blood pressure reductions are sustained throughout day and night when the dietary pattern is maintained 7.

Synergistic Effects with Other Interventions

The DASH diet demonstrates substantially increased effectiveness when combined with other lifestyle modifications 1:

• Combined with sodium reduction: Produces additive BP-lowering effects beyond either intervention alone 1, 4
• Combined with weight loss: Effect size substantially increased, nearly doubling BP reduction 1
• Combined with medication: Further reduces systolic BP by approximately 3 mm Hg in patients already on antihypertensive drugs 1

Additional Cardiovascular Benefits

Beyond blood pressure control, the DASH diet improves multiple cardiovascular risk factors 1:

• Lowers LDL cholesterol by 11 mg/dL when compared to typical American diet 1
• Reduces total cholesterol and triglycerides 2, 8
• Lowers homocysteine levels 8
• May reduce risk of chronic kidney disease 1

The American Heart Association notes that HDL cholesterol is lowered by approximately 4 mg/dL, though this effect is consistent across demographic subgroups 1.

Effectiveness Across Populations

High-quality evidence demonstrates the DASH diet lowers blood pressure across diverse demographic groups 1:

• Both men and women benefit equally 1
• African American and non-African American adults show significant reductions 1
• Older and younger adults respond to the intervention 1
• Both hypertensive and nonhypertensive individuals experience BP lowering 1

Clinical Implementation

The 2017 ACC/AHA Hypertension Guideline provides a Class I, Level A recommendation for the DASH diet in adults with elevated BP or hypertension 1. The diet is appropriate for primary prevention of hypertension and as initial treatment for uncomplicated stage 1 hypertension before initiating drug therapy 1.

Counseling by a registered dietitian is recommended to facilitate implementation and ensure appropriate adaptation to individual needs 1. Multiple resources including NHLBI guides and structured programs are available to assist patients in adopting the DASH pattern 1.

Important Modifications for Specific Populations

For patients with chronic kidney disease: The standard DASH diet requires modification due to its high potassium content 1. Medical nutrition therapy services should be utilized to adapt the diet appropriately 1.

For patients on dialysis: The DASH diet should not be used without substantial modification 1.

For patients with advanced kidney disease: Potassium supplementation is contraindicated, and the high-potassium nature of DASH requires careful adjustment 1.

DASH Variations

The OmniHeart trial tested two modifications of the standard DASH diet 1:

• Higher protein version: Replacing 10% of carbohydrate calories with protein lowered systolic BP by an additional 1-3 mm Hg compared to standard DASH 1
• Higher unsaturated fat version: Replacing 10% of carbohydrate calories with unsaturated fat (8% monounsaturated, 2% polyunsaturated) produced similar additional BP reductions 1

These variations may be particularly beneficial in patients with BP 140-159/90-95 mm Hg, where they lowered systolic BP by 3 mm Hg relative to standard DASH 1.

Common Pitfalls to Avoid

Do not rely solely on the DASH diet without addressing other modifiable risk factors including weight loss, physical activity, and alcohol moderation 1, 5. The comprehensive lifestyle approach produces superior outcomes 1.

Do not assume patients can implement DASH without structured support: The typical Western diet is fundamentally different from DASH, with less than 20% of US adults consuming recommended servings of fruits and vegetables 1. Behavioral interventions with at least 14 sessions over 6 months are needed for sustained dietary change 2, 3.

Do not overlook the need for sodium reduction: While DASH alone is effective, combining it with sodium restriction to <1,500 mg/day produces substantially greater BP reductions 1.

Evidence Limitations

Recent Cochrane systematic review findings indicate that while the DASH diet effectively reduces blood pressure and improves lipid profiles, long-term evidence on hard cardiovascular outcomes (myocardial infarction, stroke, cardiovascular mortality) remains limited 9. All available trials assessed primary prevention only, with no data on secondary prevention effectiveness 9. The certainty of evidence for major cardiovascular events is low to very low due to small sample sizes and short follow-up periods 9.