Measurement Errors in Dietary Assessment Using Self-Reported 24-Hour Recalls in Low-Income Countries and Strategies for Their Prevention.

Securing accurate measurements of dietary intake across populations is challenging. Of the methods, self-reported 24-h recalls are often used in low-income countries (LICs) because they are quick, culturally sensitive, do not require high cognitive ability, and provide quantitative data on both foods and nutrients. Measuring intakes via 24-h recalls involves 1) collecting data on food intakes, 2) the appropriate use of relevant food-composition data for calculating nutrient intakes, and 3) statistically converting observed intakes to "usual intakes" for evaluating nutrient adequacy or relations between foods and nutrients and health outcomes. Like all dietary methods, 24-h recalls are subject to random errors that lower the precision and systematic errors that can reduce accuracy at each stage of the measurement protocol. Research has identified the potential sources of measurement errors in 24-h recall protocols and emphasized that sources of random error can be reduced by incorporating standardized quality-control procedures and collecting more than one 24-h recall per person, with the number depending on the study objective. Careful design of the initial 24-h recall protocol can take into account potential sources of systematic error, such as day of the week, season, age, etc. Other sources of systematic error (e.g., energy underreporting) can best be detected by including a reference measure (e.g., doubly labeled water to measure energy expenditure). Alternatively, 24-h recall intakes of energy can be compared with same-day weighed intakes. Nevertheless, very few studies in LICs have assessed the validity of 24-h recalls in their study settings or adopted recommended standardized protocols to mitigate random errors. Hence, efforts should be made to improve the assessment, analysis, and interpretation of self-reported 24-h recall data for population studies in LICs. Accurate and precise dietary intake data at the national level can play an essential role in informing food, nutrition, and agricultural policies; food fortification planning; and compliance to food-based dietary guidelines.