title: Cis-9, trans-11 conjugated linoleic acid is synthesized from vaccenic acid in lactating women.
abstract: We studied the incorporation of the trans-11 vaccenic-1-(13)C acid ((13)C-VA) into milk and endogenous synthesis of cis-9, trans-11 conjugated linoleic acid (CLA) in lactating women. Subjects (n = 4) were 247 +/- 30 d postpartum, weighed 70.8 +/- 3.7 kg, breast-fed at least 6 times/d and consumed self-selected diets. After an overnight fast, they consumed the (13)C-VA (2.5 mg/kg body wt). Milk samples were obtained by complete breast expression at 0, 2, 4, 8, 12, 18, 24, and 48 h post-(13)C-VA ingestion. Lipid was extracted using chloroform:methanol. Fatty acids were methylated and converted to dimethyl disulfide and Diels-Alder derivatives before analysis by gas chromatography mass spectrometry. The mean (13)C-enrichment of milk VA was 3.1% at 8 h and reached maximal enrichment of 7.6% at 18 h. The (13)C enrichment of milk cis-9, trans-11 CLA reached a maximum of 0.4% at 18 h, confirming its conversion of VA to the Delta9-desaturase enzyme product. In the subjects examined, a portion (<10%) of the cis-9, trans-11 CLA present in milk was endogenously synthesized from VA.
authors.affiliation: Department of Food Science and Human Nutrition, Washington State University, Pullman, WA 99164-6376, USA.
authors.forename: Erin E
authors.initials: EE
authors.lastname: Mosley
authors.forename: Michelle K
authors.initials: MK
authors.lastname: McGuire
authors.forename: Janet E
authors.initials: JE
authors.lastname: Williams
authors.forename: Mark A
authors.initials: MA
authors.lastname: McGuire
mesh_terms: D002247:Carbon Isotopes; D002788:Cholesterol Esters / Q000378:metabolism; D004032:Diet; D015930:Diet Records; D005227:Fatty Acids / Q000378:metabolism; D005260:Female; D008401:Gas Chromatography-Mass Spectrometry; D006801:Humans; D007700:Kinetics; D007774:Lactation; D044243:Linoleic Acids, Conjugated / Q000032:analysis / Q000096:biosynthesis* / Q000097:blood; D008055:Lipids / Q000097:blood; D008745:Methylation; D008895:Milk, Human / Q000737:chemistry; D009829:Oleic Acids / Q000378:metabolism*; D010743:Phospholipids / Q000097:blood; D014280:Triglycerides / Q000097:blood
chemical_list: D002247:Carbon Isotopes; D002788:Cholesterol Esters; D005227:Fatty Acids; D044243:Linoleic Acids, Conjugated; D008055:Lipids; D009829:Oleic Acids; D010743:Phospholipids; D014280:Triglycerides; C503589:cis-9, trans-11-conjugated linoleic acid; C050413:11-octadecenoic acid