Dietary Patterns, Sodium Intake and Blood Pressure (DASH - Sodium)

BACKGROUND:

High blood pressure, defined as systolic blood pressure greater than or equal to 140 mm Hg or diastolic blood pressure greater than or equal to 90 mm Hg, or taking antihypertensive medication, affects 24 percent of the United States adult population or about 50 million people. Because the risk of cardiovascular disease and stroke increases with increasing blood pressure throughout the entire range of blood pressure levels, people with blood pressure above the optimal level of 120/80 are at increased risk of disease. Approximately 48 percent of the adult population have blood pressure either normal but above optimal levels or have Stage 1 hypertension, a prevalence which increases with age. To combat this highly prevalent condition, primary prevention through lifestyle modification represents a highly promising strategy for public health.

DASH - Sodium extended research from DASH trial to address several issues of relevance to clinical practice and public health and capitalized on the success of DASH by following the multicenter outpatient feeding study model. The model permitted a true test of efficacy because of high adherence and follow-up rates. In addition, the population studied across four geographic areas, encompassing individuals with diastolic blood pressure between 80-95 mm Hg and systolic blood pressure <160 mm Hg, was broadly representative, thus making the results generalizable to a large portion of the United States population.

DESIGN NARRATIVE:

The effects on blood pressure of three levels of sodium intake and two dietary patterns were compared. The combined impact of sodium reduction with dietary intervention was evaluated as a potential non-pharmacologic treatment alternative to drug therapy for stage one hypertension or for maintaining normal blood pressure levels. The two dietary patterns were a control diet that represented the typical American diet and an intervention diet (DASH diet) that was high in fruits, vegetables, included whole grains, poultry, fish, and nuts, and reduced in fats, red meat, sweets, and sugar-containing beverages and dairy products. The three levels of sodium were higher (current United States intake), intermediate (current recommended levels), and lower (potentially optimal levels). Participants were assigned to one of the two dietary patterns using a parallel group design and were fed at each sodium level using a randomized cross-over design.