Childhood Nutrition Linked to Adult Intellectual Function

Susan Jeffrey

July 11, 2008

July 11, 2008 — Long-term follow-up of men and women in Guatemala who participated as children in a trial of nutritional supplementation suggests that enhanced childhood nutrition is associated with improved intellectual functioning in adulthood, even after the effects of schooling have been controlled for.

"Our data, which suggest an effect of exposure to an enhanced nutritional intervention in early life that is independent of any effect of schooling, provide additional evidence in support of intervention strategies that link early investments in children to continued investments in early-life nutrition and in schooling," the researchers, with first author Aryeh D. Stein, PhD, from the Hubert Department of Global Health, Rollins School of Public Health at Emory University, in Atlanta, conclude.

Their findings are published in the July issue of the Archives of Pediatrics and Adolescent Medicine.

Both Nutrition and Schooling Key

Schooling is a key component to the development of literacy, reading comprehension, cognitive functioning, "and thus of human capital," the authors write. The literature suggests, moreover, that poor nutritional status in early childhood is associated with poor performance on cognitive tests in later childhood or adulthood, they note. "Therefore, both nutrition and early-childhood intellectual enrichment are likely to be important determinants of intellectual functioning in adulthood."

Between 1969 and 1977, the Institute of Nutrition of Central America and Panama (INCAP) conducted a study of growth and development of children living in 4 villages in Guatemala. The villages were randomly assigned to receive supplementation for children consisting of either atole, a supplement containing Incaparina (a vegetable protein), dry skim milk, and sugar, providing 900 kcal/L, or of fresco, a juice drink, containing 330 kcal/L, all from sugar. The trial showed that exposure to atole was associated with improved growth rates and a reduced prevalence of stunting at age 3 years.

Since then, this cohort has been followed prospectively. For this analysis, researchers were able to get adequate information on 1448 (68.4%) of 2118 individuals from the original study group of 2392, who were not known to have died in the meantime. They compared intellectual functioning of individuals who were exposed to atole between birth and 24 months of age with that of individuals who were exposed instead to fresco or who were exposed to atole at other ages.

The main outcomes of interest were scores on the Serie Interamericana (InterAmerican Series) tests of reading comprehension and the Raven Progressive Matrices, obtained between May 1, 2002 and April 30, 2004, when the surviving subjects were an average of 32 years of age. Years of schooling were established by interview.

The authors report that in models controlling for years of schooling and other predictors of intellectual functioning, exposure to atole between birth and 24 months of age was associated with an increase of 3.46 points (95% CI, 0.53 – 8.18) on the InterAmerican Series and 1.74 points (95% CI, 0.53 – 2.95) on the Raven Progressive Matrices.

There was no statistical interaction, they note, between exposure to atole at birth to age 24 months and years of schooling on either of these outcomes.

"Nutrition in early life is associated with markers in child development in this population, and exposure to atole for most of the first 3 years of life was associated with an increase of 0.4 years in attained schooling, with the association being stronger for females (1.2 years of schooling)," the authors conclude. "Thus, schooling might be in the causal pathway between early childhood nutrition and adult intellectual functioning."

The nutrition supplement used in this study, while not commercially available, was made ofwidely available foods (skim milk powder, Incaparina, and sugar), Dr. Stein told Medscape Neurology & Neurosurgery. "Incaparina, a maize-based complementary infant food, is widely used in Guatemala to this day," he added. "The findings from this study should therefore be applicable in other settings of chronic undernutrition."

 

The study team is continuing its investigations on the long-term consequences of improving child nutrition, he noted.

This study was supported by grants from the National Institutes of Health (NIH) and the National Science Foundation. The NIH, the Thrasher Fund, and the Nestle Foundation have funded the work of the INCAP Longitudinal Study since its inception, the paper notes. The authors report no financial disclosures.

Arch Pediatr Adolesc Med. 2008;162:612-618. Abstract

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