title: Evidence that palmitic acid is absorbed as sn-2 monoacylglycerol from human milk by breast-fed infants.
abstract: Milk fatty acids consist of about 20-25% palmitic acid (16:0), with about 70% of 16:0 esterified to the sn-2 position of the milk triacylglycerols. Hydrolysis of dietary triacylglycerols by endogeneous lipases produces sn-2 monoacylglycerols and free fatty acids, which are absorbed, reesterified, and then secreted into plasma. Unesterified 16:0 is not well absorbed and readily forms soaps with calcium in the intestine. The positioning of 16:0 at the sn-2 position of milk triacylglycerols could explain the high coefficient of absorption of milk fat. However, the milk lipase, bile salt-stimulated lipase, has been suggested to complete the hydrolysis of milk fat to free fatty acids and glycerol. These studies determined whether 16:0 is absorbed from human milk as sn-2 monopalmitin by comparison of the plasma triacylglycerol total and sn-2 position fatty acid composition between breast-fed and formula-fed term gestation infants. The human milk and formula had 21.0 and 22.3% of 16:0, respectively, with 54.2 and 4.8% 16:0 in the fatty acids esterified to the 2 position. The plasma triacylglycerol total fatty acids had 26.0 +/- 0.6 and 26.2 +/- 0.6% of 16:0, and the sn-2 position fatty acids had 23.3 +/- 3.3 and 7.4 +/- 0.7% of 16:0 in the three-month-old exclusively breast-fed (n = 17) and formula-fed (n = 18) infants, respectively.(ABSTRACT TRUNCATED AT 250 WORDS)
authors.affiliation: Department of Pediatrics, University of British Columbia, Vancouver, Canada.
authors.forename: S M
authors.initials: SM
authors.lastname: Innis
authors.forename: R
authors.initials: R
authors.lastname: Dyer
authors.forename: C M
authors.initials: CM
authors.lastname: Nelson
mesh_terms: D001942:Breast Feeding; D005227:Fatty Acids / Q000378:metabolism; D005989:Glycerides / Q000378:metabolism*; D006801:Humans; D007225:Infant Food; D007231:Infant, Newborn; D007408:Intestinal Absorption / Q000502:physiology*; D008055:Lipids / Q000097:blood; D008895:Milk, Human / Q000737:chemistry*; D019308:Palmitic Acid; D010169:Palmitic Acids / Q000493:pharmacokinetics*; D010743:Phospholipids / Q000097:blood
chemical_list: D005227:Fatty Acids; D005989:Glycerides; D008055:Lipids; D010169:Palmitic Acids; D010743:Phospholipids; D019308:Palmitic Acid