A diet high in F&V and low fat dairy foods to lower blood pressure in adolescents

Hypertension (high blood pressure) affects more than 65 million Americans⁽¹⁾ and is a factor in 67% of heart attacks, 77% of strokes, and 18% of all-cause mortality in the U.S.⁽²⁾. Thus, the public health burden of this disease is enormous. Among youth, hypertension is no longer a rare disease, affecting 7 million children and adolescents(³⁾. Numbers are expected to grow with the evolving pediatric obesity epidemic in the U.S.⁽⁴⁾.

Dietary modification is recommended as a first-line approach for children and teenagers with high blood pressure; however, evidence for the effectiveness of dietary intervention to lower blood pressure in youth is limited⁽⁵⁾. Promising research in adults showed that a dietary pattern emphasizing fruits, vegetables, low fat dairy that is also low in fat and sodium (the DASH diet) dramatically lowered blood pressure compared to other dietary approaches⁽⁶⁾. While the DASH diet is being advocated by leading health experts to manage hypertension in children and teenagers⁽⁵⁾, the effectiveness of this dietary pattern on lowering blood pressure in this age group has not been tested clinically.

Toward this purpose, our research group evaluated the effectiveness of a 3-month clinic-based behavioral nutrition intervention emphasizing a diet high in fruits, vegetables, and low fat dairy foods that was also low in fat and sodium (the DASH intervention) versus routine outpatient hospital-based nutrition care on changing diet and blood pressure in adolescents with elevated blood pressure⁽⁷⁾. Fifty-seven adolescents with a clinical diagnosis of hypertension, newly enrolled in a pediatric outpatient treatment center, were randomly assigned to the DASH intervention or routine care. The teenagers in the DASH intervention received a single, 60 minute counseling session with the dietitian focused on the DASH diet and strategies to include fruits, vegetables and low fat dairy foods into the diet while lowering fat and sodium. The counseling session was followed by 10 weekly phone calls by a trained nutrition interventionist and 4 mailings focused on behavior change strategies to Promote adoption of the DASH diet (i.e., food tracking, goal setting, action planning, and handling high risk situations). A 10-module illustrated manual, provided to each participant in the DASH group was designed to help adolescents acquire more detailed knowledge about the DASH diet. Participants were encouraged to make gradual dietary changes to achieve 8 servings per day of fruits and vegetables, 3 servings per day of low fat dairy foods and less than 2 servings per day of high fat and high sodium foods (i.e., foods that had >3 grams of fat and/or >480 mg sodium per serving). Parents were included in the initial DASH counseling session and were mailed 4 fact sheets related to creating a home food environment supportive of the DASH diet.

The routine care intervention did not vary from the diet treatment that is routinely provided in the treatment center and included a single 60 minute counseling session with a dietitian on dietary guidelines consistent with the National High Blood Pressure Education Program’s pediatric dietary recommendations. These included reducing dietary sodium and controlling weight by limiting high fat foods, reducing portion sizes and eating nutrient dense forms of foods. A pamphlet summarizing these recommendations was provided to participants⁽⁸⁾.

Our findings showed that the DASH group doubled their intake of fruits and vegetables, and increased their intake of potassium and magnesium by 42 and 36 percent, respectively. Moreover, the teens decreased high fat and high sodium foods by ~ 1 serving per day, and decreased total fat by 12 percent over 3 months. Notably, these positive changes in diet were accompanied by significant reductions in blood pressure compared to the routine care group who showed no or lesser changes in diet and blood pressure.

Findings from our study suggest that our 3-month clinic-based behavioral nutrition intervention emphasizing the DASH diet is effective, in the short-term, for improving dietary quality and blood pressure in adolescents with hypertension. A larger study with longer follow-up is needed to provide a more comprehensive evaluation of the DASH intervention for hypertensive adolescents over the long term.