[Micronutrient deficiencies and linear growth: a systematic review of observational studies]

This article seeks to evaluate the association of iron, vitamin A and zinc deficiencies with linear growth retardation. A systematic review of electronic databases in PubMed, LILACS and SciELO was conducted. Scientific papers published between January 1995 and March 2010 were selected, inserting the key words: (growth OR nutritional status) AND (child, preschool OR infant) AND (zinc AND iron AND vitamin A) OR (zinc AND iron) OR (zinc AND vitamin A) OR (iron AND vitamin A). Fourteen observational design studies were reviewed. In the cohort studies (two), one indicated a statistical association between iron levels and stunting; and the other revealed a statistical association between serum ferritin concentrations and an increase in height. Ten cross-sectional studies investigated the statistical association between micronutrient deficiencies and stunting, three of which resulted in an association with iron, two with vitamin A and none with zinc. Elucidation of the association between stunting and iron, vitamin A and zinc deficiencies involves difficulties of a biological nature and also related to the magnitude of these deficiencies, indicating the importance of a methodological standardization of the studies.