Within- and between-person variations as determinant factors to calculate the number of observations to estimate usual dietary intake of adolescents

Abstract

Resumo

How many 24-hour recalls or food records are required to estimate usual energy and nutrient intake?

“…Nevertheless, our results were close to other similar studies, particularly those related to the within/between variances in adolescents and to the number of 24hR or diet records replications for women 4,23 .…”

“…The study showed that to rank the adolescents' energy intake considering a correlation coefficient of 0.9, at least four replications of 24hR or food records would be necessary for boys and seven replications for girls. Costa et al 4 estimated the variances ratio ranging between 1.35 and 2.62, and also calculated that at least six replications of 24hR are needed in order to estimate the usual diet of adolescents from São Paulo, Brazil.…”

“…The variance ratios for the macro and micronutrient intake were higher than for energy. Costa et al 4 also referred to the need for at least 10 dietary assessment repetitions to estimate the usual intake of fat among adolescents from São Paulo. Therefore, studies that seek to calculate associations' measurements between the intake of specific dietary components, like the subtypes of fat, and the risk of developing diseases should be aware of Table 4 Number of days required for the estimation of energy and nutrients intake according to two different calculations.…”

“…Food records and 24hR recalls are based on foods and amounts actually consumed by an individual on one or more specific day. FFQ obtain retrospective information on the intake of specific foods during a longer period 3 , allowing to estimate usual diet, which can be described as the mean intake over an extended period of time 3,4,5 .…”

Reprodutibilidade, validade relativa e calibração de um questionário de frequência alimentar para adultos da Região Metropolitana de Porto Alegre, Rio Grande do Sul, Brasil

“…O número de replicatas do IR24h é outra limitação, uma vez que para capturar a variabilidade dia a dia de alguns nutrientes poderia ser necessário mais do que os três utilizados neste estudo, conforme demonstrado no trabalho de Costa et al 33 , em que o menor e o maior números de dias de observação da dieta foram seis e onze para carboidratos e proteínas, respectivamente 34 . Entretanto, pode não ser factível a realização de mais IR24h, uma vez que isto exigiria maior disponibilidade dos participantes, aumentando a possibilidade de perdas, como foi o caso neste estudo.…”