Dietary quality assurance processes of the DASH-Sodium controlled diet study.

A thorough quality assurance (QA) program upholds the integrity of nutrition research studies by yielding reliable data and results. Continually evaluating the implementation of a procedure against a goal and making adjustments when needed enhance the quality of a study's conduct and outcomes. Controlled diet studies require QA processes at various steps beginning with the screening of study participants, through diet preparation and delivery to data collection. Staff training and observations with monitoring activities, are important so tasks are completed according to protocol. When several clinical sites participate as partners in a controlled diet study, uniform procedures must be followed and a formal standardized QA program will assist. The Dietary Approaches to Stop Hypertension (DASH)-Sodium study employed such a program, described in this article, that included training staff, observing procedures, monitoring data for completeness and accuracy, evaluating processes, giving feedback, and documenting that tasks were done according to protocol. Furthermore, QA processes were used in the areas of participant screening, orientation, diet adherence, food procurement and preparation, and exit interviews. Other researchers may implement similar activities to ensure quality in their nutrition research programs.

Food group sources of nutrients in the dietary patterns of the DASH-Sodium trial.

The aim of this paper is to identify major food group sources of several essential nutrients in the two dietary patterns used in the DASH-Sodium trial: a control diet and the DASH dietary pattern. The DASH-Sodium trial was a multicenter, randomized, controlled-feeding trial comparing the effects of three levels of sodium and two dietary patterns on blood pressure. Nutrient contents of all the menus for both the control and the DASH diets were analyzed and examined for their dietary sources from 13 food groups. Contributions of all foods within each food group to each nutrient were averaged then weighted to reflect the actual distribution of energy levels in the study. Nutrient contents across the three sodium levels are very similar within each diet. Refined grains and whole grains are the major energy sources for the control and the DASH diet, providing 35% and 23% to the total intake, respectively. Nutrient-dense whole grains contributed greatly, ranging from 11% to 46%, to the higher intakes of protein, fiber, calcium, magnesium, potassium, zinc, and folate in the DASH diet. Vegetables, in addition to being a good source for fiber, vitamins A, C, E, and folate, also contributed an average of 15% to the intakes of magnesium, potassium, and calcium in the DASH diet. Differences in nutrient contents between the control and the DASH diets were accomplished by varying the selection of food items (eg, refined grains vs whole grains) and quantities of certain food groups (eg, less red meats and higher amounts of fruits and vegetables). The DASH dietary pattern recommends four to five servings of fruits; four to five servings of vegetables; two to three servings of low-fat dairy products; seven to eight servings of grain products (preferably whole grains); two or less servings of meats, poultry, and fish per day; and four to five servings of nuts, seeds, and legumes per week for a 2,000 kcal diet. Each of these food groups contributes critical nutrients across various sodium levels. It is important to emphasize all food groups when trying to follow this proven dietary pattern.