Adherence Monitoring Tool for Controlled Feeding Studies

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ObjectiveTo devise a dietary adherence monitoring tool for use in controlled human feeding trials involving free‐living study participants.MethodsA scoring tool was devised to measure and track dietary adherence for an 8‐wk randomized trial evaluating the effects of two different dietary patterns on metabolic health outcomes. One dietary pattern is based on the 2010 Dietary Guidelines for Americans; and the other using recent dietary intake data from the What We Eat In America (WWEIA) National survey. In our trial, all foods and beverages are provided to the study participants. The scoring system is a modified version of that used in the Dietary Approaches to Stop Hypertension (DASH) feeding study. Study volunteers maintain detailed daily food logs that are used to score their adherence in these categories. These scores are then adjusted using weigh‐backs of foods not consumed, when a discrepancy between self‐report and weigh backs arise. Adherence scores are assigned on a daily basis to four categories: 1) adherence to the provided study foods (SF), 2) intake of non‐study foods (NSF), 3) intake of coffee or tea that was not provided (C/T), and 4) addition of salt, pepper, herbs or other spices (S/P/S). A score of 0 indicates complete adherence in all categories. For the study and non‐study food categories, scores of 1, 2 or 3 represent deviations of <1, 1–2.9, or ≥ 3 servings/d. In the C/T or S/P/S categories, scores of 1 indicate that these items were added by the participant. A Wilcoxon's signed‐rank test was used to compare the difference in adherence between SF and NSF.ResultsScores for the first ten participants suggest that deviations from adhering to eating all of the study foods (0.6 ± 1.0) were greater than deviations from eating non‐study foods (0.1 ± 0.5) (p=0.002). There were only a total of 10 reported instances of C/T deviations and 4 of S/P/S deviations during the full 8‐wk study for these ten participants.ConclusionsThe scoring tool enables us to closely follow free‐living participants on a daily basis in controlled feeding trials and has the potential to improve adherence while the volunteer is actively enrolled in the study. In our study, this scoring tool will be paired with additional objective checks of adherence, including measurements of body weight and urinary nitrogen, sodium and potassium to more fully characterize dietary adherence.Support or Funding InformationSupported by National Dairy Council, Campbell Soup Company, and the USDA project number #2032‐51530‐022