Use of Asymmetric Models to Estimate the Distribution of Usual Nutrient Intakes

The issue of estimating usual nutrient intake distribution is a challenge for dietitian and statistics. The 24-hour recall is usually one method to collect data and the distributions of usual nutrient intakes are, in general, asymmetric. Thus, this study aims to use asymmetric models in order to estimate the distribution of usual nutrient intakes. Data were drawn from a Health Inquires Survey from São Paulo city, Brazil. It was a cross-sectional population-based study with 1662 individuals. Two 24-hours recalls were collected and it was used in the Nutrition Data System for Research (NDSR) to obtain micronutrient intake data. A random intercept model was used to fit the distribution of micronutrient intake data, which characterizes different measures at the same subject. Asymmetric distributions were proposed for response variable and, for the random effect, a normal distribution was used. The results based on asymmetric models were compared with the National Cancer Institute (NCI) method for amount. No important differences among methods were observed, but this new approach shows advantages: it does not require data transformation and results can be directly interpreted from the estimated parameter of the considered distribution.