A Nutrition Intervention to Lower Blood Pressure in Adolescents

Efficacy of a Nutrition Intervention Emphasizing Fruits, Vegetables and Dairy to Lower Blood Pressure in Adolescents

The purpose of this study is to evaluate the efficacy of a 12-week, clinic-based, behavioral nutrition intervention emphasizing fruits, vegetables, and low fat dairy compared to routine nutrition care on changing diet quality and blood pressure post-treatment and at short-term follow-up in adolescents with hypertension.

Among youth, hypertension is no longer a rare disease, affecting about 7 million children and adolescents. Numbers are increasing with the evolving pediatric obesity epidemic in the US. More adolescents than children have primary hypertension, which tracks into adulthood and has been linked with preclinical indicators of adverse cardiovascular events in adults. Early prevention and intervention efforts are needed to address this increasing public and individual health problem. The purpose of this project is to evaluate the immediate and sustained impact of a 3-month clinic-based behavioral nutrition intervention emphasizing a diet high in fruits, vegetables, and low fat dairy, and low in fat and sodium (the DASH intervention) versus routine nutrition care on changing diet quality and blood pressure in adolescents with pre-hypertension or hypertension. The DASH intervention will include a printed participant manual, 1 individual counseling session with a dietitian, 4 mailings and 10 telephone calls on behavioral strategies to promote dietary change. Routine care will include 1 individual counseling session with a dietitian on dietary guidelines consistent with those of the National High Blood Pressure Education Program. Adolescents with prehypertension or hypertension will be randomly assigned to the DASH intervention or routine nutrition care after pre-treatment assessment. Post-treatment and at 3-month follow-up, outcome measures will be assessed including dietary intake and blood pressure. Our expectations are that the DASH intervention will significantly improve dietary quality and blood pressure in adolescents with elevated blood pressure compared to that observed as a result of routine nutrition care. The findings from this study are expected to improve the manner in which hypertension among adolescents is being treated in the clinical setting and contribute to the enhancement of the cardiovascular health of the target population.

All measurements were made in the Cincinnati Children's Hypertension Clinic by trained clinic staff blinded to treatment assignment.

The DASH diet used in this intervention was slightly modified from the original version of the DASH diet for adults to more closely conform to the unique nutritional needs of adolescents. Details of the intervention have been published (Couch, SC et al. J Pediatrics 2008; 152: 494-501)

Routine care did not deviate from the nutrition counseling that was routinely given to all new patients at the Cincinnati Children's Hypertension Clinic. Details of routine care have been published (Couch, SC et al. J Pediatrics 2008; 152: 494-501)

Systolic blood pressure (SBP) and diastolic blood pressure (DBP) measurements were performed with a mercury sphygmomanometer according to standardized procedures. SBP and DBP were measured two times and averaged. SBP and DBP z-scores were determined from these average measurements based on established norms.

Dietary intake was assessed with 3, 24-hour recalls collected over a 2-week period (2 weekdays and 1 weekend day) before each assessment visit using the validated multi-pass method. Recalls were collected from the adolescent by telephone interview and coded by a trained research dietitian. Adolescents were trained in the use of a 2-dimensional food portion size model to enhance recall of different food volumes and dimensions. Food recalls were analyzed for selected nutrients and servings of fruits, vegetables, low fat dairy foods and high sodium and fat containing foods using the Minnesota Nutrient Data Systems software (version 5.0, 2003). Indicators of diet quality were recorded as average number of daily servings of fruits, vegetables, low fat dairy foods and high fat and sodium containing foods.

Inclusion Criteria: clinical diagnosis of prehypertension or stage 1 hypertension age 11-18 years english speaking Exclusion Criteria: stage 2 or secondary hypertension target organ damage or symptomatic hypertension type 1 or 2 diabetes treated with anti-hypertensive medications or other blood pressure altering medications are unwilling to stop use of vitamins, minerals or antacids containing calcium or magnesium do not have full medical clearance from a physician to participate

Couch SC, Saelens BE, Levin L, Dart K, Falciglia G, Daniels SR. The efficacy of a clinic-based behavioral nutrition intervention emphasizing a DASH-type diet for adolescents with elevated blood pressure. J Pediatr. 2008 Apr;152(4):494-501. doi: 10.1016/j.jpeds.2007.09.022. Epub 2007 Nov 5.