Aside from the fact that DHA can be retroconverted to EPA in the body, any zoner (Eiconut?) aware of any studies showing whether DHA has any direct effect on delta-5 desaturase? Thanks a lot. Matt

Hey Matt- sorry for the delay in response--I know you are working on a paper for this---to be honest, I couldn't find much. A couple rat studies (1)(2) indicate DHA's inhibitory effect of D5D, but I am unsure if this would be the result of DHAs retroconversion back to EPA or an effect of DHA itself. That second study was quite interesting as DHA showed an inhibitory effect on the delta-9 desaturase enzyme as well. This enzyme is also under hormonal influence by insulin-- and an increase in its activity increases the desaturation of stearic acid (18:0) to oleic acid (18:1n-9). Known as the Saturation Index, the ratio of stearic-oleic acid is believed to be a marker of membrane fluidity, and a lowering of the index (lower stearic relative to oleic) has been seen in breast cancer (3)(4), colorectal cancer (5), gall bladder carcinogenesis (6) and a number of other malignancies (6). Would love to have the opportunity to read the finished product when you're finished-- -- aka Eiconut (1) Gronn M, et al "Effects of dietary purified eicosapentaenoic acid (20:5(n-3)) and docosahexaenoic acid (22:6(n-3)) on fatty acid desaturation and oxidation in isolated rat liver cells" Biochem Biophys Acta 1992 Apr 8;1125(1):35-43 (2) Engler MM, et al "Dietary docosahexaenoic acid affects stearic acid desaturation in spontaneously hypertensive rats" Lipids 2000 Sep;35(9):1011-5 (3) Pala V, et al "Erythrocyte membrane fatty acids and subsequent breast cancer-a prospective Italian study" J Natl Cancer Institute 2001 Jul 18;93(14):1088-95 (4) Chajes V, et al "Fatty-acid composition in serum phospolipids and risk of breast cancer: an incident case-control study in Sweden" Int J Cancer 1999 Nov 26;83(5):585-90 (5) Kelly SB, et al "Erythrocyte stearic acid desaturation in patients with colorectal carcinoma" Dis Colon Rectum 1990, 33:1026-30 (6) Manoj Pandey, et al "Erythrocyte membrane fatty acid profile and saturation index in gall bladder carcinogenesis: a case control study" World Journal of Surgical Oncology 2003

Hi Eiconut – Sorry, too, for my delay but I was finishing up with finals and the holidays before responding back. Thanks for the references…I, too, could not find a study showing whether DHA has a direct effect on D5D, but I agree with you that any inhibitory effect on D5D is probably due to its retroconversion to EPA. My paper is finished and I would love for you to read it and add to it, edit it, comment on it, etc. What is your email? I hope it can receive large attachments (it is over 40 pages of MS Word so quite a big file). Thanks again, Matt

You can reach me at eiconut@comcast.net. Looking forward to it.