title: Development and validation of a food photography manual, as a tool for estimation of food portion size in epidemiological dietary surveys in Tunisia.
abstract: BACKGROUND
  Estimation of food portion sizes has always been a challenge in dietary studies on free-living individuals. The aim of this work was to develop and validate a food photography manual to improve the accuracy of the estimated size of consumed food portions.
  
  
  METHODS
  A manual was compiled from digital photos of foods commonly consumed by the Tunisian population. The food was cooked and weighed before taking digital photographs of three portion sizes. The manual was validated by comparing the method of 24-hour recall (using photos) to the reference method [food weighing (FW)]. In both the methods, the comparison focused on food intake amounts as well as nutritional issues. Validity was assessed by Bland-Altman limits of agreement. In total, 31 male and female volunteers aged 9-89 participated in the study.
  
  
  RESULTS
  We focused on eight food categories and compared their estimated amounts (using the 24-hour recall method) to those actually consumed (using FW). Animal products and sweets were underestimated, whereas pasta, bread, vegetables, fruits, and dairy products were overestimated. However, the difference between the two methods is not statistically significant except for pasta (p<0.05) and dairy products (p<0.05). The coefficient of correlation between the two methods is highly significant, ranging from 0.876 for pasta to 0.989 for dairy products. Nutrient intake calculated for both methods showed insignificant differences except for fat (p<0.001) and dietary fiber (p<0.05). A highly significant correlation was observed between the two methods for all micronutrients. The test agreement highlights the lack of difference between the two methods.
  
  
  CONCLUSIONS
  The difference between the 24-hour recall method using digital photos and the weighing method is acceptable. Our findings indicate that the food photography manual can be a useful tool for quantifying food portion sizes in epidemiological dietary surveys.
authors: Department of Nutrition, Ecole Supérieure des Sciences et Techniques de la Santé de Tunis, Université de Tunis El Manar, Tunis, Tunisia.|LR 12SP05, Surveillance et Epidémiologie Nutritionnelle en Tunisie, Tunis, Tunisia; mongia.bouchoucha@yahoo.fr.
authors: Mongia
authors: M
authors: Bouchoucha
authors: Department of Nutrition, Ecole Supérieure des Sciences et Techniques de la Santé de Tunis, Université de Tunis El Manar, Tunis, Tunisia.
authors: Mouna
authors: M
authors: Akrout
authors: UR 14SP01, Analyse des effets sur la santé des changements climatiques et environnementaux, Hôpital Abderrahmane Mami, Ariana, Tunisia.|Departement of Epidemiology, Faculty of Medicine of Tunis, Tunis-El Manar University, Tunis, Tunisia.
authors: Hédia
authors: H
authors: Bellali
authors: Service of Endocrinology-Diabetology, Rabta Hospital, Tunis, Tunisia.
authors: Rim
authors: R
authors: Bouchoucha
authors: Department of Nutrition, Ecole Supérieure des Sciences et Techniques de la Santé de Tunis, Université de Tunis El Manar, Tunis, Tunisia.
authors: Fadwa
authors: F
authors: Tarhouni
authors: UR 14SP01, Analyse des effets sur la santé des changements climatiques et environnementaux, Hôpital Abderrahmane Mami, Ariana, Tunisia.|Department of Physiology, Faculty of Medicine of Tunis, Tunis-El Manar University, Tunis, Tunisia.
authors: Abderraouf Ben
authors: AB
authors: Mansour
authors: Departement of Epidemiology, Faculty of Medicine of Tunis, Tunis-El Manar University, Tunis, Tunisia.
authors: Béchir
authors: B
authors: Zouari
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D002648:Child; D004034:Diet Surveys / Q000379:methods*; D016021:Epidemiologic Studies; D005260:Female; D006801:Humans; D008297:Male; D008370:Manuals as Topic; D008875:Middle Aged; D015596:Nutrition Assessment; D010781:Photography / Q000379:methods*; D064787:Portion Size; D015203:Reproducibility of Results; D012858:Size Perception; D014416:Tunisia / Q000453:epidemiology; D055815:Young Adult
keywords: 24-hour recall; Tunisia; food portion sizes; portion size estimation; portion size photographs; weighed foods