The Importance of Long Chain Polyunsaturated Fatty Acids in Infant Development and Immune Response.

M.T. Clandinin, C.J. Field, and J. Van Aerde.

Nutrition and Metabolism Research Group

University of Alberta, Edmonton, Alberta, Canada T6G 2P5

Essential fatty acids are required for infant growth and development. Longer chain metabolites of 18:2 n-6 and 18:3 n-3 are significant structural components of membranes in many cell types and are essential to a variety of functions (ex. in brain and retina) and have potential to impact on the development of the immune system.

Infants are born with a degree of immunological immaturity and T lymphocyte function is poorly developed at birth. The reduced ability of infants to respond to mitogens may be the result of the low number of memory/antigen primed/T cells in the infant or limited ability to produce cytokines (particularly IFN-, IL-4 and IL-10). There have been many important changes in optimizing breast milk substitutes for infants, however few have been directed at replacing factors in breast milk that convey immune benefits. Recent research has been directed at the neurological, retinal and membrane benefits of adding 20:4n-6 (AA) and 22:6n-3 (DHA) to infant formula. In adults and animals, feeding DHA impacts on T cell function. However, the effect of these lipids on development and function of the infants’ immune system is not known. Compared to a standard formula, feeding a formula containing DHA + AA increases the proportion antigen mature (CD45RO+) CD4⁺ cells, improves IL-10 production and reduces IL-2 production to levels similar to that of human milk-fed infants.