Background: There are controversial reports about the therapeutic effects of fish oil in patients with ulcerative colitis. Polyunsaturated fatty acids cause an oxidative injury at the site of inflammation because of a decrease in the colonic antioxidant defense system. Vitamins A and E inhibit lipid peroxidation in the tissues. The aim of the present study was to evaluate possible useful effects of fish oil, vitamin A and vitamin E enriched diets on the improvement of colonic damage and reduction of inflammation in experimental acute ulcerative colitis.

Materials and Methods: Eighty adult Wistar rats were randomly divided into treatment and pretreatment groups. Rats in the treatment groups received intrarectal saline (control group, n=10) or acetic acid (1 ml, 4%) to induce acute ulcerative colitis. After the induction of colitis, rats were fed for 1 wk with standard diet (colitis group, n= 10), diet enriched with fish oil (10%) and 1.2 mg/Kg vitamin A (FA group n=10), or diet enriched with fish oil (10%) and 2 gr/Kg vitamin E (FE group, n=10). The control group was fed with standard diet. After 1 wk the degree of tissue injuries was assessed by macroscopical and histopathological scores of colonic mucosa. In pretreatment groups, rats were fed for 1 wk with standard diet (colitis group, n=10), diet enriched with fish oil (10%) and 1.2 mg/Kg  vitamin A (PFA group n=10) and or diet enriched with fish oil (10%) and 2 gr/Kg  vitamin E (PFE group, n=10) and then they received intrarectal acetic acid to induce ulcerative colitis. The control group was fed with standard diet and received intrarectal saline. Two days after the induction of colitis the degree of tissue injuries was assessed by macroscopical and histopathological scores of colonic mucosa.

Results: Acetic acid administration induced severe macroscopic (Total score=5.0±0.0) and microscopic damages to mucosal tissue (Total score=9.7±1.3). The Rats with colitis in the treated group FE at 1wk showed significantly less macroscopic (Total score=1.0±0.3) and microscopic colonic damage (Total score=2.7±0.7) compared with those in colitis group. However in the FA group with macroscopic (Total score=3.2±0.7) and microscopic colonic damage (Total score=7.8±.8) there was no significant difference with colitis group. Pretreatment of acetic acid-treated rats with FA and FE diets did not result in any improvements in macroscopic and microscopic scores.

Conclusion: These results may reflect that fish oil and vitamin E enriched diets could be beneficial in the treatment of ulcerative colitis.