Reliability and Validity of Nutrient Assessment Applications for Canadian Endurance Athletes: MyFitnessPal and Cronometer

INTRODUCTION: The purpose of the present observational study was to assess the inter-rater reliability and validity of two free nutrition apps, MyFitnessPal (MFP) and Cronometer (CRO), among Canadian endurance athletes. METHODS: Two raters independently input 43 three-day food intake records (FIR) (27M/16F) into MFP and CRO, and one rater input each FIR into ESHA Food Processor® using the reference standard 2015 Canadian Nutrient File (CNF) database. RESULTS: MFP showed a consistent difference in measurements between raters for total energy and carbohydrates (absolute reliability), but the difference was too small to be clinically meaningful; further, raters were inconsistent for sodium and sugar (relative reliability), particularly among men. MFP showed poor validity for total energy, carbohydrates, protein, cholesterol, sugar, and fibre, with discrepancies for total energy, carbohydrates and sugar being driven by women, and protein differences by men. Rationale for low reliability and validity may be due to the copious options for each food entry in MFP, including non-verified consumer entries. Possible rationale for gender differences may be more detailed and descriptive FIRs (reliability) and generally more varied dietary patterns (validity) in women compared to men. Conversely, CRO showed good to excellent inter-rater reliability for all nutrients and good validity for all nutrients except for fibre and vitamins A and D, with no differences between genders. Rationale for low validity of fibre may be due to how it is represented in the software (i.e., total vs. soluble), and rationale for vitamins A and D may be due to fortification practices differing between brands and countries. Bland-Altman plots for inter-rater reliability and validity revealed smaller bias, narrower LOAs, and better horizonal spread of data when using CRO compared to MFP. CONCLUSION: Given the unique energy and nutrient needs of athletes, they should be aware that MFP may provide dietary information that does not accurately reflect true intake, and that CRO could serve as a promising alternative.