Methodology for Meal Composite Production and Analysis: Lessons From the Nutrition for Precision Health Study

Objectives: To establish consistent methodology for quality control monitoring for diets provided to participants in the Nutrition for Precision Health study across study sites. Methods: The goal of the Nutrition for Precision Health (NPH) study is to understand how individuals respond to different dietary patterns. Participants consume three different diets for 13 days each in a crossover design. The 3 diet patterns were selected using foods commonly consumed and for their potential to elicit individual response variability. Nutrient specifications were determined using published data. Three-day menus were developed for each diet to meet the nutrient specifications and food group serving targets using a standard nutrient database. Staff prepared meals using standardized ingredients and preparation methods to achieve meals consistent in macronutrients, visual appeal, texture and taste. To determine accuracy within diet targets and consistency across sites, each site prepared and homogenized the 2100kcal menus using a standard protocol and sent them for chemical analysis. To be considered accurate within the diet targets, the 3-day menu average from each site was set to be within acceptable ranges (∼+/- 2.5% of the planned value) for protein, saturated fat, and sodium or carbohydrates, depending on the diet. Coefficient of variation (% CV) was used to determine consistency across sites targeting ≤10% CV for each nutrient of interest. Results outside +/-10% of the median were used to identify outliers and address potential issues with production and/or analysis. This process was repeated until each issue passed the benchmark. Results: Initial results revealed production and analytical inconsistencies. A more tightly controlled process for preparing meals and composites, and additional standardized analyses procedures specific to the NPH diets were established. Sites prepared menus using the refined procedures resulting in alignment with nutrient targets and improved consistency across sites. Conclusions: Establishing a controlled process for meal production and composite preparation resulted in alignment with diet targets and consistency across sites allowing initiation of meal provision. This quality control process will continue throughout the NPH study.