Arachidonic acid to eicosapentaenoic acid ratio in blood correlates positively with clinical symptoms of depression.
Adams PB, Lawson S, Sanigorski A, Sinclair AJ. Lipids. 1996 Mar;31 Suppl:S157-61.

Dietary ratio of (n-6)/(n-3) polyunsaturated fatty acids alters the fatty acid composition of bone compartments
and biomarkers of bone formation in rats.
Watkins BA, Li Y, Allen KG, Hoffmann WE, Seifert MF. J Nutr. 2000 Sep;130(9):2274-84.

Effect of omega-3 fatty acid supplementation on the arachidonic acid:eicosapentaenoic acid ratio
Burns T, Maciejewski SR, Hamilton WR, Zheng M, Mooss AN, Hilleman DE.
Pharmacotherapy. 2007 May;27(5):633-8. Pharmacotherapy. 2007 May;27(5):633-8.

Evolutionary aspects of diet, the omega-6/omega-3 ratio and genetic variation: nutritional implications for chronic diseases.
Simopoulos AP. Biomed Pharmacother. 2006 Nov;60(9):502-7. Epub 2006 Aug 28. 

Imbalances in Dietary Consumption of Fatty Acids, Vegetables, and Fruits Are Associated With Risk for Crohn's Disease in Children.
Amre DK, D'Souza S, Morgan K, Seidman G, Lambrette P, Grimard G, Israel D, Mack D, Ghadirian P, Deslandres
C, Chotard V, Budai B, Law L, Levy E, Seidman EG. Am J Gastroenterol. 2007 Jul. 7

Omega-6 and omega-3 fatty acids predict accelerated decline of peripheral nerve function in older persons.
Lauretani F, Bandinelli S, Benedetta B, Cherubini A, Iorio AD, Blè A, Giacomini V, Corsi AM, Guralnik JM, Ferrucci L.
Eur J Neurol. 2007 Jul;14(7):801-8.

Tissue n-3 and n-6 fatty acids and risk for coronary heart disease events.
Harris WS, Poston WC, Haddock CK. Atherosclerosis. 2007 Jul;193(1):1-10. Epub 2007 May 15.

Depressive symptoms, omega-6:omega-3 fatty acids, and inflammation in older adults.
Kiecolt-Glaser JK, Belury MA, Porter K, Beversdorf DQ, Lemeshow S, Glaser R. Psychosom Med. 2007 Apr;69(3):217-24. Epub 2007 Mar 30.

Relationship of plasma polyunsaturated fatty acids to circulating inflammatory markers.
Ferrucci L, Cherubini A, Bandinelli S, Bartali B, Corsi A, Lauretani F, Martin A, Andres-Lacueva C, Senin U, Guralnik JM. J Clin Endocrinol Metab. 2006 Feb;91(2):439-46. Epub 2005 Oct 18.

Omega-3 fatty acids upregulate adult neurogenesis
Beltz BS, Tlusty MF, Benton JL, Sandeman DC. Neurosci Lett. 2007 Mar 26;415(2):154-8. Epub 2007 Jan 7.