title: Determination of intra- and inter-individual variability and its effect on the number of days required to assess the usual intake of a 1-year-old infant population.
abstract: Diet variability influences the accuracy of the assessment of the relationship between nutrient intake and disease. The present study investigates intra- and inter-individual variability in an infant population at 12 months. The mothers of 79 infants completed a 7-day weighted food record. No significant difference in nutrient intake was observed between males and females. For some nutrients an intra-/inter-individual variability ratio > 1 was found. Adjustment for total calorie intake slightly altered the intra-/inter-individual variability ratio of many nutrients. An error margin of 10% or less for calories can be expected within an 18-day study. Most nutrients however would need to be studied for over 30 days to give an error margin < or = 10%. For dietary cholesterol, vitamins A, B6, C, and E, bracketing the error within the 10% margin would require an unrealistic time frame. Adjustments for calorie intake reduced the number of days in the dietary record for some nutrients. A lower intra/inter-individual variability ratio was seen when data for adults and older infants were compared.
authors.affiliation: Fifth Department of Paediatrics, University of Milan, Italy.
authors.forename: R
authors.initials: R
authors.lastname: Bellù
authors.forename: M T
authors.initials: MT
authors.lastname: Ortisi
authors.forename: E
authors.initials: E
authors.lastname: Riva
authors.forename: M
authors.initials: M
authors.lastname: Giovannini
mesh_terms: D000704:Analysis of Variance; D015930:Diet Records; D002149:Energy Intake / Q000502:physiology*; D004734:Energy Metabolism; D005260:Female; D006801:Humans; D007206:Individuality; D007223:Infant; D007225:Infant Food; D007558:Italy; D008297:Male; D009749:Nutrition Surveys; D013997:Time Factors