The DASH-2 Diet (DASH-II)

Four years after the DASH Diet was published in the New England Journal of Medicine, the DASH-2 Diet (DASH-II) study was published. The DASH Diet showed good improvement in blood pressure. However, the study authors wanted to further evaluate the effects of sodium combined with a DASH Diet.

So many patients at our Tulsa Integrative Medicine preventive cardiology clinic want to avoid or reduce their medications yet want to maximize their health and reduce their risk of cardiovascular disease. The DASH-2 diet is an excellent tool to help achieve this goal.

The DASH-2 study sought to evaluate the effect of different levels of sodium intake in conjunction with the DASH Diet. 412 participants were randomly assigned to eat either a Standard American Diet or the DASH Diet (combined diet in the DASH Diet Study). Within the DASH Diet, participants were assigned three different levels of sodium intake for 30 consecutive days and in random order.

Participants were adults with a blood pressure of 120-159 over 80-95.

The 3 sodium levels were:

High: 150 mmol per day (3.45 grams sodium)
Intermediate: 100 mmol per day (2.3 grams sodium)
Low: 50 mmol per day (1.15 grams sodium)

However, the total daily sodium intake was proportionate to their overall caloric intake – bigger or more active people got more.

There was a 2 week run-in period where participants ate a high-sodium control diet. After the run-in period they were randomized to either the control diet or the DASH Diet. Each group ate their diet at one of the 3 sodium levels for 30 consecutive days. Their sodium levels were randomly reassigned every 30 days in a Crossover design.

Inclusion and exclusion criteria were similar to the DASH Diet except they were aiming for 50% blacks and 50% women in this trial. 95% of the DASH-Diet group and 94% of the control-diet group completed the study.

If any patient had a blood pressure more than 170 over 105 it necessitated a repeat reading. If it remained elevated then they were referred to their doctor for management.

Results

Blood pressure (both systolic and diastolic) significantly decreased in a stepwise fashion based on sodium intake. Low sodium intake had a greater effect on lowering blood pressure in the control group than in the DASH-Diet group. Blood pressure lowering based on sodium intake was greater in hypertensive participants than in those without hypertension.

The combination of the DASH-Diet and low sodium group had the most profound effect on reducing blood pressure. It decreased systolic blood pressure 11.5 mmHg (in hypertensive patients) and 7.1 mmHg (in normotensive patients) (p<0.001 in all groups).

Of note, there were 36 participants in the control-diet group but only 7 in the DASH-Diet group who had blood pressures of 170 over 105 or more. 18 were in the high sodium group (combined control group and DASH-diet group, 22 in the intermediate group, and 3 during the low sodium group. None of these occurred in the DASH-Diet low sodium group.

DASH-2 Diet Conclusions

In patients who were not hypertensive, systolic blood pressure was 7.1 mmHg in the low sodium DASH Diet (DASH-2 Diet). However, if you were hypertensive, the response was even greater with decrease of 11.5 mmHg.

Basically, the DASH-2 Diet does an excellent job of reducing blood pressure as a stand alone intervention and should be foundational in any hypertension campaign.