title: Missing anti-proliferative effect of fish oil on rectal epithelium in healthy volunteers consuming a high-fat diet: potential role of the n-3:n-6 fatty acid ratio.
abstract: Several studies have indicated dietary fish oil (FO) as a protective agent in colon carcinogenesis. Rectal cell proliferation as an intermediate biomarker of cancer risk was shown to be reduced by dietary FO in patients with adenomatous polyps and healthy subjects consuming a low-fat diet. Because the synthesis of prostaglandins (PG) which seem to be involved in this process is dependent on the ratio of n-3:n-6 fatty acids in the diet, the present study was designed to investigate whether this FO effect is also detectable in volunteers eating a high-fat diet (50% of energy) with a low n-3:n-6 ratio of 0.25. Twelve healthy volunteers received in addition to a controlled basal diet either FO (4.4 g n-3 fatty acids/day) or corn oil supplements (double-blind, crossover) for two 4-week periods. No significant differences between the two study periods were found for rectal cell proliferation as assessed by bromodeoxyuridine immunohistochemistry and ornithine decarboxylase activity, as well as for mucosal PGE2 release and mucosal membrane fatty acid composition. The results emphasize the importance of dietary n-3:n-6 ratio in determining the effects of FO on rectal cell proliferation.
authors.affiliation: Department of Medicine, University of Würzburg, Germany.
authors.forename: H P
authors.initials: HP
authors.lastname: Bartram
authors.forename: A
authors.initials: A
authors.lastname: Gostner
authors.forename: B S
authors.initials: BS
authors.lastname: Reddy
authors.forename: C V
authors.initials: CV
authors.lastname: Rao
authors.forename: W
authors.initials: W
authors.lastname: Scheppach
authors.forename: G
authors.initials: G
authors.lastname: Dusel
authors.forename: A
authors.initials: A
authors.lastname: Richter
authors.forename: F
authors.initials: F
authors.lastname: Richter
authors.forename: H
authors.initials: H
authors.lastname: Kasper
mesh_terms: D000284:Administration, Oral; D000328:Adult; D002455:Cell Division / Q000187:drug effects; D018592:Cross-Over Studies; D004042:Dietary Fats, Unsaturated / Q000008:administration & dosage / Q000378:metabolism*; D015232:Dinoprostone / Q000378:metabolism; D004311:Double-Blind Method; D004847:Epithelial Cells; D004848:Epithelium / Q000187:drug effects / Q000378:metabolism; D015525:Fatty Acids, Omega-3 / Q000008:administration & dosage / Q000378:metabolism*; D043371:Fatty Acids, Omega-6; D005231:Fatty Acids, Unsaturated / Q000008:administration & dosage / Q000378:metabolism*; D005260:Female; D005395:Fish Oils / Q000494:pharmacology*; D006801:Humans; D008297:Male; D009955:Ornithine Decarboxylase / Q000378:metabolism; D012007:Rectum / Q000166:cytology / Q000187:drug effects* / Q000378:metabolism
chemical_list: D004042:Dietary Fats, Unsaturated; D015525:Fatty Acids, Omega-3; D043371:Fatty Acids, Omega-6; D005231:Fatty Acids, Unsaturated; D005395:Fish Oils; D009955:Ornithine Decarboxylase; D015232:Dinoprostone