Effects of fish oil on rectal cell proliferation, mucosal fatty acids, and prostaglandin E2 release in healthy subjects

Abstract Background: Experimental studies have indicated dietary fish oil as a protective agent in colon carcinogenesis. Prostaglandins have been suggested to be involved in this process. In the present study, the effects of fish oil on rectal cell proliferation (i.e., intermediate biomarker of cancer risk), mucosal membrane fatty acids, and prostaglandin E 2 (PGE 2 ) release were investigated in 12 healthy volunteers. Methods: In addition to a controlled basal diet, the test subjects received either fish oil (4.4 g ω-3 fatty acids/day) or corn oil supplements for two 4-week periods in a double-blind, crossover trial. Rectal cell proliferation was determined by bromodeoxyuridine immunohistochemistry and ornithine decarboxylase activity. After 2-hour incubation with bromodeoxyuridine, PGE 2 concentration in the incubation medium was measured by radioimmunoassay. Mucosal membrane fatty acids were analyzed by gas chromatography. Results: Bromodeoxyuridine labeling index (9.2% vs. 10.9%; P −1 ·h −1 ; P 2 release from rectal biopsy specimens (435.5 vs. 671.5 pg/ mg wet tissue; P Conclusions: The results support the hypothesis that dietary fish oil may protect against colon cancer.