Submitted to: Present Knowledge in Nutrition Book Chapter
Publication Type: Peer reviewed journal
Publication Acceptance Date: 12/1/2000
Publication Date: 8/1/2001
Citation: Pawlosky, R.J., Novotny Dura, J., Britz, S.J., Clevidence, B.A. 2001. Methods for determining the metabolism of alpha-linolenic acid in humans from intrinsically-labled food. Present Knowledge in Nutrition. Book Chapter.56:75-77. Interpretive Summary: An analysis was made of the metabolism of alpha-linolenic acid (18:3n-3) to the long-chain polyunsaturated fatty acids (PUFAs), 20:5n-3, 22:5n-3, and 22:6n-3 that had been labeled with carbon-13 from kale that had been grown in a carbon-13 atmosphere and fed to a human subject. Gas-chromatography and mass spectrometry were used to measure the fatty acids. The time-course profiles and rate constants were determined using a software program (WinSAAM, Windows Simulation and Modeling program, National Cancer Institute, NIH). This model was useful in providing an understanding on how long- chain polyunsaturated fatty acids are made in humans beginning with linolenic acid that was derived from a labeled-food. The results were compared to another human study that was carried out using a chemically synthesized form of the compound.
Technical Abstract: A physiologic multi-compartmental model for the metabolism of alpha-linolenic acid (13C-18:3n-3) to the long-chain polyunsaturated fatty acids (PUFAs), 13C-20:5n-3, 13C-22:5n- 3, and 13C-22:6n-3 was constructed from data obtained from a human subject who had consumed 0.513 g of 13C-18:3n-3 from a labeled-food (kale). The concentrations of the labeled-fatty acids were determined by gas-chromatography-mass spectrometry in the negative ion mode and GC-flame ionization detection was used to determine the fatty acid total amounts of the fatty acids. The kinetic profiles and fractional transfer rate constants were determined by using the WinSAAM (Windows Simulation and Modeling program) to construct the appropriate time-curves, which were fitted to the data. This compartmental model was useful in providing a framework for quantifying long-chain PUFA production in the metabolism of linolenic acid that was derived from a labeled-food and the results were comparable to a study that was carried out using a chemically synthesized form of labeled-linoleate.