Copyright © 2008 by Indian Society of Gastroenterology Original Article T he intestinal microflora is a complex and exactly balanced ecosystem of various bacteria. Some of these bacteria such as bifidobacterium and lactobacilli have beneficial effects for the body. They are involved in the prevention of infectious diarrhea, 1 protection of intestinal barrier system, 2,3,4 production of short-chain fatty acids for enterocytes, metabolism of carcinogenic substances and neurotoxic components, 5 vitamin synthesis, and stim- ulating of the immune system. 5 It is suggested that they have beneficial effects in attenuating some disorders such as certain allergies, 6–9 irritable bowel syndrome, 10,11,12 non-alcoholic steatohepatitis, 13 hypothalamic pituitary ad- renal axis disturbances, 14 and infectious diseases. 1,15 Recent studies indicate that probiotics can ameliorate inflammatory bowel disease and its related conditions such as arthralgia and colon cancer. 16,17,18 On the other hand, some studies have shown that fatty acids high in n-3 can attenuate inflammation of colitis; 19 but there is no study evaluating the interaction between these fatty acids and probiotics in intestinal inflammation. This study aimed to examine the effects of different dietary oils on the number of different cecal bacteria in experimental colitis. Methods Animals and diets Six- to eight-week-old female BALB/C mice (18–20 g) were obtained from the Pasteur Institute (Tehran, Iran). Mice were raised in the animal care facility with a 12 h–12 h light-dark cycle with unlimited access to food and water. Mice were randomized into the following diet groups of 8 mice each: (a) standard chow diet containing beef tallow as its fat component, or (b) a semi-synthetic diet, with 20% energy from the following oils (Table 1): safflower oil (high in 18:2n-6), canola oil (high in 18:1n-9 and 18:3n-3) and fish oil (high in 20:5n-3, 22:6n-3). Experimental diets were produced in-house (Table 2). All diets were isocalor- ic and isonitrogenous. The diets were stored in airtight containers in a cold room at 4 o C, and fed to the animals daily. Weight and mortality were monitored for 4 weeks. Induction of colitis: After 3 weeks, mice were fasted for 24 h before induction of colitis. After ether anesthesia, a thin catheter was inserted 5 cm into the rectum, and 1 mL of 4% acetic acid (pH 2.3) was slowly infused into the rectal lumen. After 30 sec exposure, excess fluid was The effect of dietary oils on cecal microflora in The effect of dietary oils on cecal microflora in The effect of dietary oils on cecal microflora in The effect of dietary oils on cecal microflora in The effect of dietary oils on cecal microflora in experimental colitis in mice experimental colitis in mice experimental colitis in mice experimental colitis in mice experimental colitis in mice Azita Hekmatdoost, 1 Mohammad M Feizabadi, 2 Abolghasem Djazayery, 1 Abbas Mirshafiey, 3 Mohammad R Eshraghian, 4 Samira M Yeganeh, 2 Reza Sedaghat, 5 Kevan Jacobson 6 Departments of 1 Human Nutrition, 3 Immunology and Pathobiology, and 4 Biostatistics and Epidemiology, School of Health, Tehran University of Medical Sciences, Tehran; 2 Department of Microbiology, School of Medicine, Tehran University of Medical Sciences, Tehran; 5 Division of Pathology, Shahed University of Medical Sciences, Tehran, Iran; and 6 Division of Gastroenterology, BC Children’s Hospital, Vancouver, Canada Objectives: In spite of growing evidence indicating the benefits of probiotics, the effects of different dietary oils on intestinal microflora and probiotics have not been elucidated. This study aimed to examine the effects of different dietary oils on intestinal microflora in an experimental model of colitis. Methods: Eight-week mice were fed isocaloric diets varying only in fat composition for 4 weeks. The oils used were fish oil, canola oil, safflower oil, and chow diet containing beef tallow. Colitis was induced by intracolonic administration of acetic acid on day 21. The inflammation and fecal microflora and serum lipid profiles were evaluated 1 week after induction. Results: Inflammation was highest in the chow diet group followed by safflower, canola, and fish oil fed groups, respectively. The number of fecal bacteroideceae was greater, whereas the number of fecal bifidobacteria was lower in mice fed beef tallow than the other ones. In addition, fish oil reduced the plasma level of triacylglycerole significantly. Conclusion: Polyunsaturated fatty acids (PUFAs) can affect intestinal microflora increasing the number of probiotics. PUFAs might be recommended in addition to probiotics for the prevention and/ or maintenance treatment of colitis. Indian J Gastroenterol 2008 Sep-Oct; 27: 186-189.