UBC Theses and Dissertations
Influence of dietary fatty acids and positional distribution of dietary fatty acids on plasma lipids, visual acuity and cognitive development in term infants Nelson, Carolanne Michele
Arachidonic acid (20:4n-6) and 22:6n-3 are incorporated into the CNS during development. Deficiency of 18:3n-3 during development reduces 22:6n-3 and alters function of the retina and brain. As of 1999, infant formulas in North America contain 18:2n-6 and 18:3n-3, but not 20:4n-6 or 22:6n-3, whereas formulas in Europe, Asia and South American may contain Ion-chain fatty acids from sources that include fish oils, egg phospholipids and single cell oils. It is not known if 20:4n-6 and 22:6n-3 are essential nutrients for normal brain and retina development in term infants. Human milk TG has 16:0 preferentially esterified at the sn-2 position, whereas in infant formula 16:0 is predominantly at the sn-1,3 position. The effect of milk and formula TG fatty acid distribution on plasma lipid fatty acids is not known. These studies determined whether preferential looking acuity or novelty preference differs between breast-fed infants and infants fed formula with 18:3n-3 (1% of energy) and no 20:4n-6 or 22:6n-3. The influence of the milk and formula TG fatty acid distribution on the distribution of fatty acids in plasma lipids and lipoproteins was also determined in a randomized double-blind study with infants fed formula with 16:0 preferentially esterified at the 2 position, a standard formula or breast-fed. These studies found no association between visual acuity and erythrocyte or plasma PL 22:6n-3 at three mo, and no difference in visual acuity at any age to 18 mo between breast-fed and formula-fed infants. 16:0 was found to be higher in the plasma TG 2 position of the breast-fed infants and the infants fed the synthesized TG formula than infants fed the standard formula. These studies also showed about 50% of the 2 position 16:0 of milk and synthesized TG formula was conserved through digestion, absorption, reesterification to TG and secretion in chylomicron TG. Furthermore, the distribution of TG in milk and formula did influence plasma lipids, notably, 18:3n-3. Analysis of the lipoprotein lipids showed high 20:4n-6 and 22:6n-3 in lysoPL, 18:2n-6 and 18:3n-3 in albumin fatty acids, and 20:4n-6 and 22:6n-3 in HDL PL. The role of these lipids in n-6 and n-3 fatty acid delivery to brain remains to be determined.
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