Identification of the trans isomers of octadecenoic acid in human milk.

The presence of trans octadecenoic acid isomers was detected and analyzed in 24 hr pooled samples of human milk. Amounts of the trans isomers of the C18 monoenes ranged from 2% to 4% of the total fatty acids. For purposes of comparison, three commonly used brands of infant formula were also analyzed and found to contain 0.1% to 1.3% of trans monoene isomers. Data indicate that breast-fed and bottle-fed infants are receiving minimal levels of trans fatty acids via milk.