Feasibility And Relative Validity Of A Digital Photo-Based Dietary Assessment: Results From The Nutris-Phone Study

Objective For dietary assessment, mobile devices with a camera can be used as an alternative to hand-written paper records. The Nutritional Tracking Information Smartphone (Nutris-Phone) study aimed to examine relative validity and feasibility of a photo-based dietary record in everyday life. Design Parallel to the photo-based technique, a weighed record was performed. Participant satisfaction was assessed by questionnaire. A trained nutrition scientist evaluated portion sizes and nutrient content was calculated (DGExpert). Spearman correlation and Bland-Altman analyses were applied. Setting Healthy, non-pregnant volunteers (>= 18 years) without intent to lose weight recruited at Ulm University, Germany. Subjects Sixty-six participants (36 % males, median age 22 center dot 0 (interquartile range 20 center dot 0-25 center dot 0) years) took pictures of foods and beverages consumed with a commercially available mobile phone. Results Significant correlation between the photo-based and weighed record was observed: energy (r=0 center dot 991), carbohydrate (r=0 center dot 980), fat (r=0 center dot 972), protein (r=0 center dot 988), fibre (r=0 center dot 941). Bland-Altman analyses indicated comparable means and acceptable 95 % limits of agreement (energy: -345 center dot 2 to 302 center dot 9 kJ (-82 center dot 5 to 72 center dot 4 kcal); carbohydrate: -15 center dot 2 to 13 center dot 1 g; fat: -6 center dot 4 to 6 center dot 4 g; protein: -5 center dot 9 to 5 center dot 6 g; fibre: -2 center dot 7 to 2 center dot 5 g). However, with increasing intake level, underestimation by the digital method was present (except for fat, all P<0 center dot 01). Over 80 % of participants were satisfied with the photo-based record. In nearly 90 %, technical implementation was without major problems. Conclusions Compared with a weighed record, the photo-based dietary record seems to be valid, feasible and user-friendly to estimate energy, macronutrient and fibre intakes, although a systematic bias with increasing levels of intake should be kept in mind.