Background: Ethnic differences in nocturnal blood pressure (BP) dipping may contribute to the increased risk for adverse cardiovascular events noted in African Americans (AAs). The DASH (Dietary Approaches to Stop Hypertension) diet has been shown to be efficacious in lowering clinic and ambulatory BP; however, the effect of the DASH diet on BP dipping is unclear.
Methods: One hundred and eighteen men and women with high clinic BP (systolic BP (SBP) 130-159; diastolic BP 85-99) and above ideal body weight were randomized to a DASH diet intervention or to a usual diet control (UC) condition. Measures of 24-h ambulatory BP were obtained at baseline and at the end of the 4-month intervention period.
Results: At baseline, AAs (n = 43) displayed blunted nocturnal SBP dipping compared to Caucasians (CAs; n = 75) and were more likely to be categorized as nondippers (<10% nocturnal decline in SBP, AAs: 51% vs. CAs: 27%). AAs randomized to the DASH diet intervention showed a significant improvement in SBP dipping postintervention compared to AAs in the UC condition (P = 0.04), whereas there was no appreciable change in SBP dipping in CAs (P = 0.72). Following the intervention, ethnic differences in SBP dipping were no longer statistically significant (nondipper status: AAs: 44% vs. CAs: 32%; P = 0.19).
Conclusions: Our study provides preliminary evidence suggesting that in overweight men and women with high BP, AAs may be especially likely to benefit from augmented SBP dipping associated with consumption of the DASH diet.