Chronobiologic assessment of the effect of the DASH diet on blood pressure.

This study compares the effect of three diets on the circadian rhythm of blood pressure (BP). Hypertension and abnormal BP variability (BPV) are major risk factors leading to morbidity and mortality from cardiovascular disease. When detected early, a dietary approach may be preferred to medication. Data stemming from ambulatory BP monitoring (ABPM) from the Dietary Approaches to Stop Hypertension (DASH) study were re-analyzed from a chronobiologic perspective. Compared to the control diet (N = 112) that had no effect on BP (from 131.2/83.5 to 131.0/83.6 mmHg), both the Fruit and Vegetable (FV; N = 113) diet and the DASH (N = 113) diet were associated with a decrease in BP (FV: from 132.6/84.4 to 129.0/82.1 mmHg; DASH: from 131.9/83.6 to 127.2/80.9 mmHg). The decrease in BP was found to be circadian stage-dependent, and to differ between men and women. Nighttime BP was decreased to a larger extent with the DASH than with the FV diet, a difference observed in women but not in men. Study participants who had a higher BP during the reference stage were more likely to decrease their BP to a larger extent after the 8-week dietary intervention. The FV and DASH diets had different effects on BPV. In view of the relatively large day-to-day variability in BP in both normotensive and hypertensive people, it is recommended to monitor BP around the clock for longer than 24 h, and to individualize the optimization of dietary or other intervention.