The DASH diet consisted of a high intake of fruits, vegetables, and low-fat dairy products. It included a wide range of sources of protein, such as meat, fish, poultry, nuts, and beans. Sugar-sweetened beverages, desserts, and red meat were restricted. In terms of nutrients, the DASH diet had a high amount of fiber and protein; low amounts of saturated fat, total fat, and cholesterol; and intake of potassium, magnesium, and calcium at levels close to the 75th percentile of U.S. consumption.

Potassium and magnesium intake was similar to the 75th percentile of U.S. consumption. Fiber intake was high. The fruits and vegetables diet consisted of more fruits and vegetables and fewer snacks and desserts than the control diet, but otherwise was similar to the control diet.

For the control diet, macronutrient intake was similar to average U.S. consumption and intake of potassium, magnesium, and calcium were similar to the 25th percentile of U.S. consumption. Sodium intake was approximately 3 g/day in each diet.

Diet intervention

Metabolites were measured using a global, untargeted, metabolomic platform in serum specimens collected at the end of the 8 week diet intervention in the DASH trial. Reverse phase, untargeted ultrahigh-performance liquid chromatography tandem mass spectrometry quantification was used to measure metabolites. Peaks were quantified by calculating the area under the curve. Data were normalized to account for day-to-day instrumental variation. Compounds were identified by comparison to a library of purified standards or recurrent unknown entities and matches were determined based on retention time, mass-to-charge ratio, and chromatographic data. A relative measure of each metabolite (not absolute) is determined. The Metabolon (Durham, NC) platform quantifies over 1,000 compounds representing a broad range of metabolic compounds, including amino acids, carbohydrates, cofactors and vitamins, energy, lipids, nucleotides, peptides, and xenobiotics (chemicals, drugs, and food components).

The change in blood pressure was defined as the blood pressure level at the end of the 8 week diet intervention minus the blood pressure level at baseline.