Effects of the DASH diet on brachial artery flow mediated dilation in adolescents with pre-hypertension and hypertension
By Amanda Thopy
Background: The presence of obesity in both adults and children has increased rapidly. Obesity in children is associated with arterial endothelial dysfunction and elevated blood pressure. Dietary interventions have empirically been shown to improve endothelial function in adults. The association between a Dietary Approaches to Stop Hypertension (DASH) dietary intervention and endothelial function in hypertensive or pre-hypertensive children has not been previously explored.
Objective: Endothelial function, as measured by brachial artery flow mediated dilation (FMD), and blood pressure were compared among adolescents with elevated blood pressure (BP) who participated in either a 6-month clinic-initiated behavioral nutrition intervention emphasizing the DASH diet or who received usual hospital-based nutrition care for BP management.
Methods: Sixty-four adolescents with pre-hypertension or stage one hypertension, newly enrolled in a hospital-based hypertension clinic, were randomized to the DASH intervention (DASH, n=33) or usual nutrition care (UC, n=31). Exclusion criteria included use of BP altering medications, receiving prior formalized diet therapy to manage BP, presence of target organ damage, having diagnosed diabetes or an eating disorder. The DASH intervention included 2 counseling sessions with a dietitian on the DASH diet, 6 mailings, and 15 telephone calls on behavioral strategies to promote dietary change. UC included 2 sessions with a dietitian on dietary guidelines consistent with those from the Fourth Pediatric Report of the National High Blood Pressure Education Program. Adolescents in both groups were prescribed calorie levels for weight maintenance.
Results: Weight, height, blood pressure and FMD were assessed at pre-treatment (baseline) and after the 6 month intervention. FMD was adjusted for pre-treatment arterial diameter at rest. Among completers (DASH, n=27; UC, n=24), post-treatment mean values for FMD were significantly greater among DASH participants relative to UC after adjustment for age, gender, race, BMI z score and pre-treatment FMD level (adjusted means + SD; 8.16 % + 1.13 vs. 5.29 % + 0.76, p=0.04). Post-treatment systolic and diastolic blood pressure was not significantly different between groups.
Conclusion: These findings suggest that a clinic-initiated behavioral nutrition intervention emphasizing the DASH diet with telephone and mail follow-up can lead to improved endothelial function in adolescents with above normal blood pressure over usual hospital-based nutrition care.
This research is supported by NIH Grant HL088567-01 (PI: Couch, SC.