Nutritional supplementation in early childhood, schooling, and intellectual functioning in adulthood: a prospective study in Guatemala.

OBJECTIVE To estimate the association of improved nutrition in early life with adult intellectual functioning, controlling for years of schooling. DESIGN Prospective cohort study. SETTING Four villages in Guatemala, as well as locations within Guatemala to which cohort members migrated. PARTICIPANTS Individuals who had participated as children in a nutrition supplementation intervention trial from March 1, 1969, through February 28, 1977 (N = 2392). From May 1, 2002, through April 30, 2004, adequate information for analysis was obtained from 1448 of 2118 individuals (68.4%) not known to have died. INTERVENTIONS Individuals exposed to atole (a protein-rich enhanced nutrition supplement) at birth through age 24 months were compared with those exposed to the supplement at other ages or to fresco, a sugar-sweetened beverage. We measured years of schooling by interview. MAIN OUTCOME MEASURES Scores on the Serie Interamericana (InterAmerican Series) tests of reading comprehension and the Raven Progressive Matrices, obtained from May 1, 2002, through April 30, 2004. RESULTS In models controlling for years of schooling and other predictors of intellectual functioning, exposure to atole at birth to age 24 months was associated with an increase of 3.46 points (95% confidence interval, -1.26 to 8.18) and 1.74 points (95% confidence interval, 0.53-2.95) on the InterAmerican Series and Raven Progressive Matrices tests, respectively. There was no statistical interaction between exposure to atole at birth to age 24 months and years of schooling on either outcome (P = .24 and P = .60, respectively). CONCLUSION Improved early-life nutrition is associated with increased intellectual functioning in adulthood after taking into account the effect of schooling.