What is the DASH (Dietary Approaches to Stop Hypertension) diet?

What is the DASH Diet?

The DASH (Dietary Approaches to Stop Hypertension) diet is an evidence-based eating pattern that emphasizes fruits, vegetables, and low-fat dairy products while reducing saturated fat, red meat, sweets, and sugar-containing beverages—designed primarily to lower blood pressure and reduce cardiovascular risk. 1

Core Components of the DASH Diet

The DASH diet is structured around specific food groups with defined serving recommendations:

• Fruits and vegetables: 5-9 servings per day, providing high levels of potassium, magnesium, and fiber 2
• Low-fat dairy products: 2-4 servings per day, contributing calcium and protein 2
• Whole grains: Emphasized as the primary carbohydrate source 1
• Lean proteins: Includes poultry, fish, and nuts while limiting red meat 1
• Reduced fats: Low in total fat, saturated fat, and cholesterol 1
• Limited sodium: Ideally less than 2,400 mg per day, with optimal target <1,500 mg per day 2
• Minimal sweets: Reduced sugar-containing beverages and desserts 1

Blood Pressure Lowering Effects

The DASH diet produces clinically significant blood pressure reductions across diverse populations:

• Overall population: Reduces systolic BP by 5.5 mm Hg and diastolic BP by 3.0 mm Hg compared to typical American diet 1
• Hypertensive individuals: Produces dramatic reductions of 11.4-11.6 mm Hg systolic and 5.3-5.5 mm Hg diastolic 1, 3
• Non-hypertensive individuals: Still effective with 3.4-3.5 mm Hg systolic and 2.2 mm Hg diastolic reductions 1
• African Americans: Particularly responsive with 6.8-6.9 mm Hg systolic reductions compared to 3.0-3.3 mm Hg in whites 1, 4
• Rapid onset: Blood pressure reductions occur within 2 weeks of starting the diet 1, 5

Additional Cardiovascular Benefits

Beyond blood pressure control, the DASH diet provides multiple cardiovascular benefits:

• Lipid improvements: Lowers LDL cholesterol by 11 mg/dL when body weight is kept stable 1
• HDL cholesterol: Modest reduction of 4 mg/dL, though this effect is consistent across subgroups 1
• No effect on triglycerides in the original trials 1
• Reduces homocysteine levels and enhances benefits of antihypertensive medications 6

Clinical Applications

For uncomplicated stage I hypertension (systolic BP 140-159 mm Hg or diastolic BP 90-99 mm Hg), the DASH diet serves as initial treatment before initiating drug therapy. 1

The diet is appropriate for multiple clinical scenarios:

• Primary prevention: Prevents hypertension in individuals with prehypertension (BP 120-139/80-89 mm Hg) 1
• Adjunct to medications: Further lowers BP in patients already on antihypertensive drugs, particularly when combined with sodium restriction 1
• Broad applicability: Effective across sex, age, race, and baseline BP categories 1

DASH Diet Variations

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

• Higher protein version: Replacing 10% of carbohydrate calories with protein lowered systolic BP by an additional 1 mm Hg overall, and 3 mm Hg in those with BP 140-159/90-95 mm Hg 1
• Higher unsaturated fat version: Replacing 10% of carbohydrate calories with unsaturated fat (8% monounsaturated, 2% polyunsaturated) produced similar additional BP reductions 1

Implementation Considerations

The DASH diet works best when combined with other lifestyle modifications for maximum cardiovascular benefit:

• Weight loss: Each 1 kg of weight loss produces approximately 1 mm Hg reduction in systolic BP; a 10 kg loss reduces systolic BP by 6.0 mm Hg 2, 3
• Sodium restriction: Reducing sodium by 80-100 mmol per day (4.7-5.8 g sodium chloride) lowers BP by an additional 4-6 mm Hg 3
• Physical activity: 150 minutes per week of moderate-intensity aerobic exercise reduces systolic BP by 4-9 mm Hg 2, 3
• Alcohol moderation: Limiting intake to ≤2 drinks per day for men and ≤1 drink per day for women reduces systolic BP by 2-4 mm Hg 2, 3

Evidence Quality and Limitations

The DASH diet has strong evidence from controlled feeding studies where all food was provided to participants 1. However, real-world implementation faces challenges:

• PREMIER trial: When participants had to buy and prepare their own food, BP reductions were smaller than in feeding studies, largely because target intake levels were rarely achieved 1
• Long-term outcomes: A 2025 Cochrane review found insufficient evidence for effects on myocardial infarction, stroke, heart failure, or mortality due to lack of long-term trials 7
• Intensive counseling: Successful dietary intervention trials typically provided 14 group sessions and 4 individual counseling sessions over 6 months 1

Despite implementation challenges, even brief physician counseling (3 minutes or less) can be effective, similar to smoking cessation advice. 1

Special Populations

The DASH diet requires modifications in certain conditions 8:

• Chronic kidney disease: Caution needed due to high potassium content, but not an absolute contraindication 8
• Patients on RAAS antagonists: Monitor potassium levels closely 8
• Chronic heart failure: May require sodium and fluid modifications 8
• Lactose intolerance: Can substitute lactose-free dairy or calcium-fortified alternatives 8

Comparison to Other Dietary Patterns

• Mediterranean diet: Shows some BP-lowering effects but has less robust evidence than DASH 2
• Vegetarian diets: Reduce systolic BP by approximately 5 mm Hg but lack the comprehensive trial evidence of DASH 1, 2
• Fruits and vegetables alone: A diet emphasizing just fruits and vegetables (without the full DASH pattern) produces about half the BP reduction of the complete DASH diet 1