Protocol of the validation of the experience sampling-based dietary assessment method (ESDAM) against doubly labeled water, urinary protein, and biomarkers.

BACKGROUND: The quest towards more feasible, low-cost yet accurate dietary assessment methods has led to the development of the new Experience Sampling-based Dietary Assessment Method (ESDAM). ESDAM is an app-based quantitative dietary assessment method to assess habitual dietary intake over a period of 2 weeks. ESDAM prompts three 2-hour recalls daily requesting to provide dietary intake on meal and food group level. The ESDAM allows to measure dietary intake near real-time in a rapid, low-cost and feasible manner. Following the user experience evaluation of the ESDAM, the validity of the ESDAM will now be assessed against objective biomarkers. METHODS: This protocol describes the validation of the ESDAM against three 24-hour dietary recalls (24-HDR), doubly labeled water, urinary nitrogen, serum carotenoids, and erythrocyte membrane fatty acids. The primary outcomes include energy intake and protein intake measured by the ESDAM in relation to energy expenditure measured by the doubly labeled water method and protein intake derived from urinary nitrogen analysis respectively. Secondary outcomes include nutrient and food group consumption derived from ESDAM and repeated 24-HDR's, beta-carotenoids as biomarker of fruit and vegetable consumption and erythrocyte membrane fatty acid composition as biomarker of dietary fatty acid composition. Blinded continuous glucose monitoring will serve as method to assess compliance to ESDAM prompts. A target sample of 115 healthy volunteers will be recruited. Validity will be evaluated by mean differences and spearman correlations between nutrient and biomarker reference values. Bland-Altman plots will be developed to assess agreement. Method of triads will allow quantifying measurement error of the ESDAM, 24-HDR's and biomarkers in relation to the (unknown) 'true dietary intake'. DISCUSSION: This protocol describes an extensive validation study of a newly developed Experience Sampling-based Dietary Assessment Method against both self-reported and objective reference methods. The main strength is the use of the state-of-the-art validation techniques using doubly labeled water, urinary nitrogen, carotenoids and erythrocyte membrane fatty acids as biomarkers for dietary intake. A limitation of the study is that the evaluation of reproducibility of the ESDAM is not included. REGISTRATION: This study is registered at ClinicalTrials.gov on (NCT06485960, date: 07/02/2024).