Blood lipid docosahexaenoic and arachidonic acid in term gestation infants fed formulas with high docosahexaenoic acid, low eicosapentaenoic acid fish oil.

The effect of fish oil high in docosahexaenoic acid (22:6n-3) and low in eicosapentaenoic acid (20:5n-3) in formula on blood lipids and growth of full-term infants was studied. Infants were fed formula with about 15% oleic acid (18:1), 32% linoleic acid (18:2n-6), 4.9% linolenic acid (18:3n-3) and 0, 0.10, or 0.22% 22:6n-3, or 35% 18:1, 20% 18:2n-6, 2.1% 18:3n-3 and 0, 0.11, or 0.24% 22:6n-3 from 3 d to 16 wk of age (n = 16,18,17,21,17,16, respectively). The formulae had < 0.1% 20:5n-3 and no arachidonic acid (20:4n-6). Breast-fed infants (n = 26) were also studied. Plasma phospholipid and red blood cell (RBC) phosphatidylcholine (PC) and phosphatidylethanolamine (PE) fatty acids were determined at 3 d and 4, 8, and 16 wk of age. These longitudinal analyses showed differences in blood lipid 22:6n-3 between breast-fed and formula-fed infants depending on the feeding duration. At 16 wk, infants fed formula with 0.10, 0.11% 22:6n-3, or 0.22% 22:6n-3 had similar 22:6n-3 levels in the plasma phospholipid and RBC PC and PE compared with breast-fed infants, and higher 22:6n-3 than infants fed formula without 22:6n-3. Formula with 0.24% 22:6n-3, however, resulted in higher plasma phospholipid 22:6n-3 than in breast-fed infants at 16, but not 4 or 8 wk of age. Plasma and RBC phospholipid 20:4n-6 was lower in formula-fed than breast-fed infants, but no differences in growth were found. Higher blood lipid C20 and C22 n-6 and n-3 fatty acids in infants fed formula with 20% 18:2n-6 and 2.4% 18:3n-3 compared with 32% 18:2n-6 and 4.9% 18:3n-3 show the increase in blood lipid 22:6n-3 in response to dietary 22:6n-3 depending on other fatty acids in the formula.