DASH Diet - DASH-Sodium Study Results and Conclusions

DASH-Sodium Study Results and Conclusions

The primary outcome of the DASH-Sodium study was systolic blood pressure at the end of the 30 day dietary intervention periods. The secondary outcome was diastolic blood pressure. The DASH-Sodium study found that reductions in sodium intake produced significantly lower systolic and diastolic blood pressures in both the control and DASH diets. Study results indicate that the quantity of dietary sodium in the control diet was twice as powerful in its effect on blood pressure as it was in the DASH diet. Importantly, the control diet sodium reductions from intermediate to low correlated with greater changes in systolic blood pressure than those same changes from high to intermediate (change equal to roughly 40 mmol per day, or 1 gram of sodium).

As stated by Sacks, F. et al., reductions in sodium intake by this amount per day correlated with greater decreases in blood pressure when the starting sodium intake level was already at the U.S. recommended dietary allowance, than when the starting level was higher (higher levels are the actual average in the U.S.). These results led researchers to postulate that the adoption of a national lower daily allowance for sodium than the currently held 2,400 mg could be based on the sound scientific results provided by this study. The US Dietary Guidelines for Americans recommend eating a diet of 2300 mg of sodium a day or lower, with a recommendation of 1500 mg/day in adults who have elevated blood pressure; the 1500 mg/day is the low sodium level tested in the DASH-Sodium study.

The DASH diet and the control diet at the lower salt levels were both successful in lowering blood pressure, but the largest reductions in blood pressure were obtained by eating a combination of these two (i.e., a lower-salt version of the DASH diet). The effect of this combination at a sodium level of 1,500 mg/day was an average blood pressure reduction of 8.9/4.5 mm Hg (systolic/diastolic). The hypertensive subjects experienced an average reduction of 11.5/5.7 mm Hg. The DASH-sodium results indicate that low sodium levels correlated with the largest reductions in blood pressure for participants at both pre-hypertensive and hypertensive levels, with the hypertensive participants showing the greatest reductions in blood pressure overall.

The DASH diet was named the best overall diet for the third year in a row by US News Health in the results released in January 2013.