Comparative Validity of Mostly Unprocessed and Minimally Processed Food Items Differs Among Popular Commercial Nutrition Apps Compared with a Research Food Database

Background: Commercial nutrition apps are increasingly used to evaluate diet. Evaluating the comparative validity of nutrient data from commercial nutrition app databases is important to determine the merits of using these apps for dietary assessment. Objective: Nutrient data from four commercial nutrition apps were compared with a research-based food database, Nutrition Data System for Research (NDSR) (version 2017). Design: Comparative validation study. Participants/setting: An investigator identified the 50 most frequently consumed foods (22% of total reported foods) from a weight-loss study in Chicago, IL, during 2017. Nutrient data were compared between four commercial databases with NDSR. Main outcome measures: Comparative validity of energy, macronutrients, and other nutrient data (ie, total sugars, fiber, saturated fat, cholesterol, calcium, and sodium). Statistical analyses performed: Intraclass correlation coefficients (ICCs) evaluated agreement between commercial databases with the NDSR for foods that were primarily un- and minimally processed and by the three most frequently consumed food groups. Bland-Altman plots determined degree of bias for calories between commercial databases and NDSR. Results: This study observed excellent agreement between NDSR and CalorieKing (ICC range = 0.90 to 1.00). Compared with NDSR, agreement for Lose It! and MyFitnessPal ranged from good to excellent (ICC range = 0.89 to 1.00), with the exception of fiber in MyFitnessPal (ICC = 0.67). Fitbit showed the widest variability with NDSR (ICC range = 0.52 to 0.98). When evaluating by food group, Fitbit had poor agreement for all food groups, with the lowest agreement observed for fiber within the vegetable group (ICC = 0.16). Bland-Altman plots confirmed ICC energy results but also found that MyFitnessPal had the poorest agreement to NDSR (mean 8.35 [SD 133.31] kcal) for all food items. Conclusions: Degree of agreement varied by commercial nutrition app. CalorieKing and Lose It! had mostly excellent agreement with NDSR for all investigated nutrients. Fitbit showed the widest variability in agreement with NDSR for most nutrients, which may reflect how well the app can accurately capture diet.