Abstract
New methods and analytical approaches are important to challenge and/or validate established beliefs in any field including the metabolism of polyunsaturated fatty acids (PUFA; polyunsaturates). Four methods that have recently been applied toward obtaining a better understanding of the homeostasis of PUFA include the following: whole-body fatty acid balance analysis, magnetic resonance imaging (MRI), 13C nuclear magnetic resonance (NMR) spectroscopy, and gas chromatography-combustion-isotope ratio mass spectrometry (GC-C-IRMS). Whole-boby balance studies permit the measurement of both the percentage of oxidation of linoleate and α-linolenate and their conversion to long-chain PUFA. This method has shown that β-oxidation to CO2 is normally the predominant metabolic fate of linoleate and α-linolenate. Furthermore, models of experimental undernutrition in both humans and animals show that β-oxidation of linoleate and α-linolenate markedly exceeds their intake, despite theoretically sufficient intake of linoleate or α-linolenate. Preliminary results suggest that by using MRI to measure body fat content, indirect whole-body linoleate balance can be done in living humans, 13C NMR spectroscopy provided unexpected evidence that linoleate and α-linolenate were metabolized into lipids synthesized de novo, an observation later quantified by tracer mass balance done using GC-C-IRMS. This latter method showed that within 48 h of dosing with 13C-α-linolenate, >80% underwent β-oxidation to CO2 by suckling rats, whereas 8–9% was converted to newly synthesized lipids and <1% to docosahexaenoate. Further application of these recently developed methods in different models should clarify the emerging importance of β-oxidation and carbon recycling in PUFA homeostasis in mammals including humans.
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Abbreviations
- GC:
-
gas chromatography
- GC-C-IRMS:
-
GC-combustion-IRMS
- IRMS:
-
isotope ratio mass spectrometry
- LC:
-
long chain
- MRI:
-
magnetic resonance imaging
- NMR:
-
nuclear magnetic resonance spectroscopy
- PUFA:
-
polyunsaturated fatty acids
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Cunnane, S.C. Application of new methods and analytical approaches to research on polyunsaturated fatty acid homeostasis. Lipids 36, 975–979 (2001). https://doi.org/10.1007/s11745-001-0808-3
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DOI: https://doi.org/10.1007/s11745-001-0808-3