The prevalence and impact of 'atypical' days in 4-day food records.J Am Diet Assoc. 2000 Apr; 100(4):421-7.JA
To understand how days with atypical food intake affect estimates of usual nutrient intake from 4-day food records.
Secondary analyses of 4-day food records (4DFRs) (n = 2,560) collected from 1,090 women, aged 50 to 79 years, who participated in the Women's Trial Feasibility Study in Minority Populations, a randomized dietary intervention trial.
Food records were classified as atypical if participants marked one or more day's food intake as "more than usual" or "less than usual." Total amounts and nutrient densities (percent of energy or grams per 1,000 kcal) were examined for all macronutrients, fiber, vitamin C, beta carotene, and calcium.
Contingency tables were used to examine associations of demographic characteristics with the likelihood of completing a 4DFR with atypical intake days. Analysis of variance was used to test whether nutrient intake differed among records with and without atypical days. Student t tests were used to identify any differences in total energy and percent energy from fat among typical and atypical intake days.
Approximately 16% of records included at least 1 atypical day. Reporting less-than-usual intake was associated with younger age, higher income, and higher body mass index. Black women were less likely to report more-than-usual intake than whites and Hispanics. Records with less-than-usual intake had lower intakes of all nutrients analyzed except alcohol; however, there were no differences in nutrient densities. Records with more-than-usual intake had higher intakes of alcohol and all nutrients except beta carotene and vitamin C, with higher nutrient density measures of alcohol and decreased nutrient density measures of protein, vitamin C, and fiber.
Atypical intake days are common in 4DFRs and they have a large effect on mean total intakes of most nutrients.
It is important for researchers to collect information on atypical intake days included in a 4-day food record. Strategies are needed to incorporate information on atypical intake days when analyzing and interpreting research results.