The effect of variations in dietary fatty acids on the fatty acid composition of erythrocyte phosphatidylcholine and phosphatidylethanolamine in human infants.

Human milk, or one of two formulas that derive their fat from vegetable oil, was fed to infants from birth until 4.5 to 6 months of age. Infants fed human mild received 2% of total fatty acids as 20 to 22 carbon polyunsaturated fatty acids. These fatty acids which are not found in vegetable oils, are synthesized by animals from the essential vegetable-derived fatty acids, linoleic and alpha-linolenic acids. Enfamil (Mead Johnson, Evansville, IN) contained three times as much linoleic acid as human milk or SMA (Wyeth Laboratories, Philadelphia, PA); however, the ratios of linoleic/alpha-linolenic acid were 9.0, 18.8, and 11.7 for Enfamil, human milk, and SMA, respectively. Erythrocyte phosphatidylethanolamine and phosphatidylcholine in infants fed human milk had significantly more 20 to 22 carbon polyunsaturated fatty acids than did those infants consuming only vegetable fat. Concentrations of 20 to 22 carbon polyunsaturated fatty acids in the erythrocyte membrane phosphatidylethanolamine and phosphatidylcholine of SMA and Enfamil-fed infants were similar despite very significant differences in the amount of dietary 18 carbon precursor. The degree of unsaturation of both erythrocyte phosphatidylethanolamine and phosphatidylcholine was highest with the feeding of human milk compared to the formulas, but the relative concentration of the four major erythrocyte phospholipids, and the ratio of membrane phosphorus/cholesterol were not affected by these diets.