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Conjugated linoleic acids: Physiological effects in animal and man with special regard to body composition
Author(s) -
Jahreis Gerhard,
Kraft Jana,
Tischendorf Frank,
Schöne Friedrich,
von Loeffelholz Christian
Publication year - 2000
Publication title -
european journal of lipid science and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.614
H-Index - 94
eISSN - 1438-9312
pISSN - 1438-7697
DOI - 10.1002/1438-9312(200011)102:11<695::aid-ejlt695>3.0.co;2-j
Subject(s) - conjugated linoleic acid , chemistry , lipolysis , food science , adipose tissue , composition (language) , linoleic acid , polyunsaturated fatty acid , sunflower oil , isomerization , biochemistry , fatty acid , philosophy , linguistics , catalysis
Institute of Nutrition, Friedrich Schiller University of Jena, Jena, Germany In the last decade, conjugated linoleic acids (CLA) have been shown to have some beneficial (but also unfavourable) effects: anticarcinogenic properties, immune modulation, reduction of body fat and increase of lean body mass, normalisation of impaired glucose tolerance, promotion of fatty streak formation, and isomer‐specific effects. The research base on CLA has been derived almost exclusively from animal models, while some of the biological properties have been fairly well‐documented, others are still open to question. For about 5 years a lot of commercial CLA mixtures have been offered. These mixtures produced from linoleic acid‐rich oil like sunflower or safflower oil by alkali isomerization contained, besides cis ‐9, trans ‐11 and trans ‐10, cis ‐12 CLA isomers (about 20—40% of each), parts of cis , cis and trans , trans isomers as well. The quality of the recent products is significantly improved and they contain only two CLA isomers: cis ‐9, trans ‐11 and trans ‐10, cis ‐12. CLA play apparently a key role in regulating body composition. Several studies showed a reduction in body fat mass and a slight increase in lean body mass depending on the species. A possible explanation for the decrease of body fat may be a stimulation of lipolysis and a reduction of lipoprotein lipase activity in adipocytes. In adipose and muscle tissue a CLA‐stimulated increase of carnitine palmitoyltransferase activity resulting in an enhanced fatty acid oxidation was shown. There is evidence that CLA provide protection against cytokine‐induced (Tumour necrosis factor‐α, interleukin‐1) skeletal‐muscle catabolism (anabolic effect). The body composition modulating effects are most impressive in rodents and seem to become smaller in pigs and in humans. Data on humans are insufficient. Further research is essential to characterize the multifunctionality of CLA in humans, in order to identify the specific physiological mechanism of the biologically active isomers and to determine the optimal level of these isomers for beneficial effects.