Assessment of feeding different amounts of arachidonic and docosahexaenoic acids in preterm infant formulas on the fatty acid content of lipoprotein lipids.

This study evaluated preterm infants of less than 2.3 kg birth weight fed commercial formula (Preemie SMA) devoid of arachidonic acid (AA) and docosahexaenoic acid (DHA) and compared this control group with similar infant groups fed one of three formulas containing a range of 0.32-1.1% AA and 0.24-0.75% DHA in the fat component of the formula. An analogous group of infants fed on their mothers' breast milk and a breast milk fortifier was also studied. Individual lipoprotein fractions were isolated from blood samples collected at 12 d of age and after a further 4 wk of feeding. The fatty acid content of individual lipid components, isolated from each lipoprotein fraction was quantitatively determined in order to identify change in marker pools of essential fatty acid. The high density lipoproteins (HDL) and low density lipoproteins (LDL) phospholipid and cholesterol ester fractions contain most of the AA and DHA found in the lipoprotein fractions (total of 0.49% and 0.35%, respectively). Infants fed a formula without AA and DHA showed a reduction in AA level in the phospholipid fraction of all lipoproteins and in the HDL and LDL cholesterol ester fraction. A reduced level of DHA was also observed primarily in the lipoprotein phospholipid fraction in comparison with infants fed breast milk or infant formula containing AA and DHA. Supplementing infant formula with increasing levels of AA and DHA produced a clear dose response in the level of AA found in the HDL and LDL phospholipid fraction. From comparison of the fatty acid levels present in the lipoproteins it appears that a formula level of 0.49% AA and 0.35% DHA provides sufficient levels of these fatty acids to achieve a similar fatty acid content to that of infants fed breast milk for the major lipoprotein fractions examined.