Article summary with Early nutrition influences developmental myelination and cognition in infants and young children by Deoni a.o. - 2018

What is the role of myelination in brain connectivity in early neurodevelopment?

During infancy and early childhood, the brain grows rapidly and nearly all cognitive, behavioral, and social-emotional functions emerge. The brain´s networks that are being shaped are being refined through different processes, including myelination. There is strong overlap in the emergence of cognitive functions and the myelination of brain regions and networks serving those functions. Early trajectories of myelination are associated with cognitive abilities and outcomes.

What is the role of nutrition regarding myelination?

The production and maintenance of myelin requires certain nutrients, such as lipids and fatty acids, proteins, minerals, and other micronutrients. Also important are choline, iron, cholesterol, zinc, phospholipids, and sphingomyelin. Deficiencies in these nutrients during infancy can significantly alter myelin content and composition and potentially disrupt normal brain function and impair cognitive outcomes.

Why is it important to research the differences between breast milk and formula milk with regards to myelination?

Differences in the nutritional composition between breast milk and formula milk may help explain the functional and cognitive differences often seen between exclusively breast versus formula-fed children. Human breast milk provides the nutrition that supports healthy physical growth, immune system development, and brain maturation. Though formula milk also contains many of these nutrients, they are often not present in the same concentration and also differ in the changing nutritional composition of human milk across an individual feed.

What are the limitations of the research comparing breast and formula feeding?

Cognitive and brain imaging studies are often cross-sectional with children pooled across large age-ranges, which makes it difficult to draw causative conclusions. The researches were often performed in older children and adolescents and relied on parental recall of infant feeding. Additionally, they treated formula-fed children as a single group, despite the variability between formula compositions.

What can be concluded with regards to the differences between breastfed children and formula-fed children?

A longitudinal study examined trajectories of brain and neurocognitive development in children who were exclusively breastfed versus formula-fed for at least three months. These are the main conclusions that can be drawn from that study:

• Exclusive breastfeeding for at least three months is associated with improved myelination, including early and late maturing brain regions and networks associated with many different cognitive and behavioral skills.
• Improved overall cognitive ability and cognitive development, including verbal and non-verbal functions, in breastfed children compared to formula-fed children.
• Structural and cognitive differences between breast-fed children and formula-fed children become evident by eighteen months of age and persist into early childhood.
• Observed differences in myelination may be predictive of previously observed white matter volume and integrity changes in older children and adolescents who were breastfed.
• It is not completely clear if the neurocognitive outcomes that are associated with breastfeeding are due to the specific nutritional, hormonal, and other constituents of breast milk per se, or if they are driven by maternal-child interaction and other environmental differences.

What can be concluded with regards to the differences in myelination in children who were formula-fed and the formula composition that they were given?

• The formula compositions associated with the highest myelin levels and cognitive scores had the highest concentration of long-chain PUFAs, choline, sphingolipids, folid acid, and phosphatides.
• Formula compositions that are high in iron, but lower in LC-PUFAs and sphingolipids appear to be associated with slower and reduced overall myelination.
• It is not possible to infer which particular nutrient or combination of nutrients is most associated with myelination trajectories. That can only be investigated through pre-clinical models in which individual nutrients can be varied and the effects followed.

What is the role of iron with regards to myelination?

Research indicates associations between iron deficiency and hypomyelination, reduced oligodendrocyte functioning, and decreased myelin basic protein concentrations. Children with prolonged iron deficiency suffer a variety of behavioral and cognitive impairments. Little is known about the effects of oversupplementation of iron. Breast milk contains little iron, and exclusively breastfed children may experience an iron deficiency. However, when healthy non-anaemic children are supplemented with iron they show reduced growth and increased fever and illness.