Three NHLBI-funded trials showed the health benefits of the DASH diet, such as lowering high blood pressure and LDL (bad) cholesterol in the blood, and shaped the final DASH eating plan recommendations.
Three NHLBI-funded trials found the following health benefits of the DASH diet.
- DASH (Dietary Approaches to Stop Hypertension Trial): The DASH diet lowers blood pressure and LDL (bad) cholesterol compared with a typical American diet alone or a typical American diet with more fruits and vegetables.
- DASH-Sodium (DASH Diet, Sodium Intake, and Blood Pressure Trial): The DASH diet lowers blood pressure better than a typical American diet at three daily sodium levels. Combining the DASH diet with sodium reduction gives greater health benefits than the DASH diet alone.
- PREMIER clinical trial: People can lose weight and lower their blood pressure by following the DASH eating plan and increasing their physical activity.
This trial included 459 adults, some with and without confirmed high blood pressure, and compared three diets including 3,000 mg daily sodium:
- Typical American diet
- Typical American diet plus more fruits and vegetables
- DASH diet
None of the plans were vegetarian or used specialty foods. After 2 weeks, participants who added fruits and vegetables to a typical American diet or those on the DASH diet had lower blood pressure than those who followed a typical American diet alone. However, the participants on the DASH diet had the greatest effect of lowering their high blood pressure.
Follow-up reports from the DASH trial showed that in addition to improving blood pressure, the DASH diet also lowered LDL cholesterol levels. High blood pressure and elevated LDL cholesterol are two major risk factors for cardiovascular disease.
This trial randomly assigned 412 participants to a typical American diet or the DASH diet. While on their assigned diet, participants were followed for a month at a high daily sodium level (3,300 mg) and two lower daily sodium levels (2,300 mg and 1,500 mg). Reducing daily sodium lowered blood pressure for participants on either diet. However, blood pressures were lower for participants on the DASH diet versus a typical American diet. Blood pressure decreased with each reduction of sodium. These results showed that lowering sodium intake and eating the DASH diet is more beneficial for lowering blood pressure than following the DASH diet alone.
The PREMIER trial included 810 participants who were placed into three groups to lower blood pressure, lose weight, and improve health. The groups included:
- Advice-only group, did not receive counseling on behavior changes
- Established treatment plan, including counseling for 6 months
- Established treatment plan, plus counseling and use of the DASH diet
After 6 months, blood pressure levels declined in all three groups. The two groups that received counseling and followed a treatment plan had more weight loss than the advice-only group. However, participants in the established treatment plan who followed the DASH diet had the greatest improvement in their blood pressure.