A study led by scientists at the UCL Institute of Child Health (ICH) provides evidence for the first time that breast milk in the infant diet is associated with changes in the structure of the brain. The study has been published by Pediatric Research in the USA.
Many studies suggest that breastfed babies perform better cognitively later in life but none has attempted to explain the actual structural effect of breast milk on the developing brain. In an unprecedented UK study, conducted in collaboration with experts at Harvard Medical School and funded by the MRC and Welcome Trust, scientists at the ICH studied a group of 50 adolescents born preterm who were breastfed as infants. Depending on the mothers’ success, the infants received between 0 and 100% of their diet as breast milk. In adolescence the researchers measured IQ and obtained brain scans.
Senior Research Fellow at the ICH and lead author of the study, Dr Elizabeth Isaacs, explains, “We looked at the proportion of breast milk in the diet and its relationship to IQ and brain structure at adolescence. All the significant relationships we found were in the boys. The greater the proportion of breast milk in their infant diet, the larger their total brain volume and the volume of white matter they had at adolescence. Furthermore, their Verbal IQ increased with a greater proportion of breast milk. We saw no such relationships among the girls. I would emphasize that this doesn’t mean that the boys’ IQ was boosted higher than that of the girls in the group; in fact, the overall cognitive scores of the boys and the girls were equal
“It seems that the brain in preterm boys is sensitive to one or more constituents in breast milk. Likely candidates are the fatty acids and cholesterol that naturally occur in breast milk. We speculate that these are contributing to the process of myelination, in which fatty deposits insulate the nerves and lead to better neural conduction. This is important in the early weeks of brain development and results in increases in white matter Breast milk may very well have an effect in girls too but in a way that our imaging did not detect.”
“The dose effect that we’ve shown here plays down the idea that IQ is solely influenced by socio-economic factors."
“These data support the hypothesis that breast milk promotes brain development, particularly white matter growth. The selective effect in males accords with animal and human evidence regarding gender effects of early diet. Our data have important neurobiological and public health implications and identify areas for future study.”
Professor Alan Lucas, a co-author and Director of the MRC Nutrition Unit at ICH, which conducted the follow-up study, commented, “In the last decade we have seen major advances in our understanding of the ways that breast milk may affect long term health and development. These effects we have observed on the structure of the brain will help to focus future research on the importance of breastfeeding, and of early nutrition in general, on long term mental ability.”
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