[Within-person variance of the energy and nutrient intake in adolescents: data adjustment in epidemiological studies].

OBJECTIVE The aim of this paper is to calculate within-person variance component of the energy and nutrient intake that can be useful to adjust intake distribution from adolescents when is available only a single 24-hour recall for each participant. It will also give an example of its use in the intake distribution adjustment in adolescents from another sample. METHODS It was used 24 hour recall from 215 adolescents living in São Paulo, Brazil. The variance components were estimated using the Software for Intake Distribution Estimation (PC-SIDE). It was made a model for each nutrient and sex of which were included covariates for day and month of intake and weight variable as well. RESULTS The within-person variance component ranged from 0.55 for mono saturated fat (female) up to 0.96 for folate (male). I was found higher values regarding to macronutrient and energy for males. In the example of the use of the variance component, it was estimated the distribution of intake of vitamin B6 with less bias, when compared to the distribution with no adjustment. CONCLUSION These results can be used to estimate habitual energy and nutrient intake for adolescent population when it is only a single dietary measurement.