Nervonic acid in red blood cell sphingomyelin in premature infants: an index of myelin maturation?

The present study addresses the question whether nervonic acid (24:1n-9) accumulation in sphingomyelin (SM) of red blood cells (RBC) could yield information on cerebrum maturation in premature infants. The study included 28 premature eutrophic infants of 31.5 wk gestational age. Eleven were fed with human milk, nine with a regular formula and eight with an alpha-linolenate-enriched formula. The fatty acid composition of the SM fraction was determined by gas-liquid chromatography on a 50-m fused silica capillary column. At 32 wk gestational age, the main fatty acids in SM were 16:0, 18:0, 20:0, 22:0, 24:0 and 24:1n-9. After five weeks of feeding, at week 37 of postconceptional age, the most striking variation was a rise in 24:1n-9, from 9.9 +/- 0.7 to 12.8 +/- 0.9 (P < 0.02), regardless of regimen in all three feeding groups. The rise in 24:1n-9 after birth in premature eutrophic infants is the beginning of a trend toward the higher levels in 24:1n-9 observed in mature newborns and older infants. The 24:1n-9 level in SM of RBC from premature infants may reflect 24:1n-9 levels in SM of brain and could thus reflect brain maturity.