Abstract
BACKGROUND: The accuracy of estimating nutritional intake and balance from photos of meals has not been well documented. However, DialBetics (DB)-our diabetes self-management support system, which is based on information and communication technologies-relies on the photos that type 2 diabetes patients take of their meals with smartphones. Therefore, we designed a study to evaluate this accuracy. METHODS: We prepared 61 dishes whose actual amount/value of total energy and each nutrient were known: protein, fat, carbohydrates, dietary fiber and salt. Their balance-the protein-fat-carbohydrate ratio-was also known, constituting the weighed food record (WFR). Smartphone photos of those dishes were taken, and three registered dietitians evaluated each dish from those photos, naming the dish and estimating the amount of each nutrient in it, plus the dish's balance. These estimated DB and WFR values were compared using the Wilcoxon matched-pairs rank-sum test; intraclass correlation coefficients (ICCs) were calculated. Agreement between the two values for each dish was assessed by Bland-Altman analysis. RESULTS: There were significant ICCs-0.84 for fat (95 % confidence interval 0.75-0.90) and 0.93 for carbohydrates (0.88, 0.96)-but no statistically significant differences between DB and WRF for other nutrients or balance. Bland-Altman analysis showed that differences between the two values were random and not biased against nutrient intake; 95 % limits of agreement were acceptable although wide (energy -198 to 210 kcal/dish; carbohydrates -22.7 to 25.8 g/dish). CONCLUSION: DB's diet evaluation by photos is reliable with apparent potential for assessing diets.