Measuring diet cost at the individual level: a comparison of three methods

• Published in: European journal of clinical nutrition Vol. 67; no. 11; pp. 1220 - 1225
• Main Authors: Monsivais, P, Perrigue, M M, Adams, S L, Drewnowski, A
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 01.11.2013; Nature Publishing Group
• Subjects: 692/700/159; 692/700/2814; Adult; Aged; Biological and medical sciences; Clinical Nutrition; Commerce; Comparative studies; Costs and Cost Analysis; Diet; Diet - economics; Diet Records; Economic aspects; Economics; Energy Intake; Epidemiology; Family Characteristics; Feeding Behavior; Feeding. Feeding behavior; Female; Food; Food prices; Food Supply - economics; Fundamental and applied biological sciences. Psychology; Humans; Income; Internal Medicine; Male; Measurement; Medical sciences; Medicine; Medicine & Public Health; Metabolic Diseases; Middle Aged; Natural foods; Nutrition Assessment; Nutritional Status; Original; original-article; Population studies; Prices and rates; Public Health; Social aspects; Social economics; Socioeconomic factors; Supermarkets; Surveys and Questionnaires; Vertebrates: anatomy and physiology, studies on body, several organs or systems; United Kingdom; economics; food prices; supermarkets; socioeconomic inequalities; Human; Costs; Socioeconomic status; Supermarket; Metabolic diseases; Feeding; Diet; Health economy; Economic aspect; Comparative study; Food
• ISSN: 0954-3007; 1476-5640; 1476-5640
• DOI: 10.1038/ejcn.2013.176

Background/objectives: Household-level food spending data are not suitable for population-based studies of the economics of nutrition. This study compared three methods of deriving diet cost at the individual level. Subjects/methods: Adult men and women ( n =164) completed 4-day diet diaries and a food frequency questionnaire (FFQ). Food expenditures over 4 weeks and supermarket prices for 384 foods were obtained. Diet costs (US$/day) were estimated using: (1) diet diaries and expenditures; (2) diet diaries and supermarket prices; and (3) FFQs and supermarket prices. Agreement between the three methods was assessed on the basis of Pearson correlations and limits of agreement. Income-related differences in diet costs were estimated using general linear models. Results: Diet diaries yielded mean (s.d.) diet costs of $10.04 (4.27) based on Method 1 and $8.28 (2.32) based on Method 2. FFQs yielded mean diet costs of $7.66 (2.72) based on Method 3. Correlations between energy intakes and costs were highest for Method 3 ( r 2 =0.66), lower for Method 2 ( r 2 =0.24) and lowest for Method 1 ( r 2 =0.06). Cost estimates were significantly associated with household incomes. Conclusion: The weak association between food expenditures and food intake using Method 1 makes it least suitable for diet and health research. However, merging supermarket food prices with standard dietary assessment tools can provide estimates of individual diet cost that are more closely associated with food consumed. The derivation of individual diet cost can provide insights into some of the economic determinants of food choice, diet quality and health.