DASH - Sodium determined, separately by race, gender, and hypertension status: 1) the effects on blood pressure of three levels of dietary sodium within the context of both a control diet and the DASH diet; 2) the effect on blood pressure of the DASH diet, relative to the control diet, at each of the three levels of sodium intake. The study also assessed whether the effect on blood pressure of going from higher to lower sodium diets differs for participants in the control and DASH diets. Lastly, the study determined whether the blood pressure effect associated with reducing sodium from the higher to the intermediate level differs from the blood pressure effect associated with reducing sodium from the intermediate to the lower level, that is, testing whether the blood pressure effects of sodium are linear across sodium levels for each diet.