title: Lowering dietary n-6 polyunsaturated fatty acids: interaction with brain arachidonic and docosahexaenoic acids.
abstract: OBJECTIVE
  Arachidonic (ARA) and docosahexaenoic (DHA) acids are the most abundant polyunsaturated fatty acids (PUFA) in the brain, where they have many biological effects, including on inflammation, cell-signaling, appetite regulation, and blood flow. The Western diet contains a high ratio of n-6: n-3 PUFA. Although interest in lowering this ratio has largely focused on increasing intake of n-3 PUFA, few studies have examined lowering dietary n-6 PUFA. This review will evaluate the effect of lowering dietary n-6 PUFA on levels and metabolism of ARA and DHA in animal models and in humans, with a primary focus on the brain.
  
  
  RESULTS
  In animal models, lowering dietary ARA or linoleic acid generally lowers levels of brain ARA and raises DHA. Lowering dietary n-6 PUFA can also modulate the levels of ARA and DHA metabolizing enzymes, as well as their associated bioactive mediators. Human studies examining changes in plasma fatty acid composition following n-6 PUFA lowering demonstrate no changes in levels of ARA and DHA, though there is evidence of alterations in their respective bioactive mediators.
  
  
  CONCLUSIONS
  Lowering dietary n-6 PUFA, in animal models, can alter the levels and metabolism of ARA and DHA in the brain, but it remains to be determined whether these changes are clinically meaningful.
authors.affiliation: Department of Nutritional Sciences, Faculty of Medicine, University of Toronto, Toronto, Ontario, Canada *Shoug M. Alashmali and Kathryn E. Hopperton contributed equally to the writing of this article.
authors.forename: Shoug M
authors.initials: SM
authors.lastname: Alashmali
authors.forename: Kathryn E
authors.initials: KE
authors.lastname: Hopperton
authors.forename: Richard P
authors.initials: RP
authors.lastname: Bazinet
mesh_terms: D000818:Animals; D001921:Brain / Q000378:metabolism*; D004281:Docosahexaenoic Acids / Q000378:metabolism; D043371:Fatty Acids, Omega-6 / Q000378:metabolism*; D005231:Fatty Acids, Unsaturated / Q000378:metabolism; D006801:Humans
chemical_list: D043371:Fatty Acids, Omega-6; D005231:Fatty Acids, Unsaturated; D004281:Docosahexaenoic Acids