, Volume 29, Issue 8, pp 541–545 | Cite as

Evidence that palmitic acid is absorbed assn-2 monoacylglycerol from human milk by breast-fed infants

  • Sheila M. Innis
  • Roger Dyer
  • Carolanne M. Nelson


Milk fatty acids consist of about 20–25% palmitic acid (16∶0), with about 70% of 16∶0 esterified to thesn-2 position of the milk triacylglycerols. Hydrolysis of dietary triacylglycerols by endogenous lipases producessn-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 thesn-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 assn-2 monopalmitin by comparison of the plasma triacylglycerol total andsn-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 thesn-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. Marked differences were found in the plasma total and the 2 position phospholipid percentage of 20∶4ω6, i.e., 11.6±0.3 and 6.9±0.6 (total), 17.7±1.4 and 9.7±0.6 (sn-2 position) and percentage of 22∶6ω3, 4.6±0.3 and 2.1±0.3 (total), 5.6±0.6 and 2.0±0.2 (sn-2 position) for the breast-fed and formula-fed infants, respectively. These studies provide convincing evidence that 16∶0 is absorbed from human milk assn-2 monoacyl-glycerol. The metabolic significance of the differences in positional distribution of fatty acids in the plasma lipids of breast-fed and formula-fed infants is not known.


Human Milk Cholesteryl Ester Milk Fatty Acid Position Fatty Acid Milk Triacylglycerols 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.



lecithin:cholesterol acyltransferase


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Copyright information

© AOCS Press 1994

Authors and Affiliations

  • Sheila M. Innis
    • 1
  • Roger Dyer
    • 1
  • Carolanne M. Nelson
    • 1
  1. 1.Department of Paediatrics, University of British ColumbiaB.C. Research Institute for Child and Family HealthVancouverCanada

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