title: The inverse association between relative abundances of oleic acid and arachidonic acid is related to alpha -linolenic acid.
abstract: BACKGROUND
  Many health effects of oils rich in oleic acid (OA, 18:1 n9) seem to be opposite those of arachidonic acid (AA, 20:4 n6), i.e. concerning cardiovascular risk. In recent studies in humans and in the rat we observed that percentages of OA and AA were inversely related, raising the question of whether the inverse association is a general one, and how it might be explained. In the present work we examine whether percentages of OA and AA are inversely associated in breast muscle lipids of chickens, and whether alpha-linolenic acid (ALA) may be related to the OA/AA ratio.
  
  
  METHODS
  The study group consisted of 163 chickens. Breast muscle was collected, and the concentration of fatty acids in muscle lipids was determined using gas chromatography. We studied association between fatty acids using bivariate correlations (Pearson) and linear regression. Synthesis of OA from stearic acid (Stear) was estimated using the OA/Stear ratio, and formation of AA from linoleic acid (LA) was estimated by the AA/LA ratio.
  
  
  RESULTS
  We found a strong inverse relationship (r = -0.942, p < 0.001; n = 163) between % OA and % AA in breast muscle lipids of the chickens. There was an inverse association (r = -0.887, p < 0.001) between the OA/Stearic acid ratio, estimating Delta9 desaturase, and the AA/LA ratio, estimating desaturases/elongase activities. Furthermore, there was a strong negative association between % AA and the OA/Stearic acid ratio (r = -0.925, p < 0.001), and % OA correlated negatively (r = -0.914, p < 0.001) with the AA/LA ratio. ALA was positively associated (r = 0.956, p < 0.001) with the OA/AA ratio, and this association prevailed when controlling for the other fatty acids. ALA was positively associated (r = 0.857, p < 0.001) with the OA/Stear ratio, but was negatively related (r = -0.827, p < 0.001) to the AA/LA ratio.
  
  
  CONCLUSIONS
  The relative abundances of OA and AA that are inversely related in muscle lipids of chickens may be explained by a feedback regulation between the synthesis of OA and AA, and related to ALA, which seems to stimulate formation of OA, and inhibit synthesis of AA, but further studies are required to clarify whether this hypothesis is valid.
authors.affiliation: Section of Preventive Medicine and Epidemiology, University of Oslo, Norway, Institute of Health and Society, Box 1130 Blindern, 0318 Oslo, Norway. a.t.hostmark@medisin.uio.no.
authors.forename: Arne Torbjørn
authors.initials: AT
authors.lastname: Høstmark
authors.forename: Anna
authors.initials: A
authors.lastname: Haug
mesh_terms: D000818:Animals; D016718:Arachidonic Acid / Q000378:metabolism*; D002645:Chickens; D018482:Muscle, Skeletal / Q000378:metabolism; D019301:Oleic Acid / Q000378:metabolism*; D017962:alpha-Linolenic Acid / Q000378:metabolism*
chemical_list: D017962:alpha-Linolenic Acid; D016718:Arachidonic Acid; D019301:Oleic Acid