Effects of dietary fat and fiber on the oxidative status of the small intestine and colon of rats

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Title: Effects of dietary fat and fiber on the oxidative status of the small intestine and colon of rats
Author: Sanders, Lisa Merle
Abstract: Colon cancer is one of the most commonly diagnosed cancers in the US , yet small intestine cancer is a rare event . While there are many similarities between these two tissues , inherent differences such as redox status , may contribute to the variation in cancer occurrence . We examined the difference in reactive oxygen species (ROS ) generation , antioxidant enzyme activity and oxidative DNA damage in the small and large intestine of rats under normal conditions and following exposure to exogenous oxidative stress . Basal ROS and antioxidant enzyme activities were greater in the colon than the small intestine , and the balance of ROS to antioxidant enzymes in the colon was more pro -oxidant than in the small intestine . During oxidative stress , ROS and oxidative DNA damage were greater in the colon than the small intestine . Thus the colon responds to oxidative stress less effectively than the small intestine , possibly contributing to increased cancer incidence at this site . We next wanted to understand how diets containing a combination of fish or corn oil and pectin or cellulose may alter the redox environment of the colon . ROS , oxidative DNA damage , antioxidant enzyme activity and apoptosis were measured in colonocytes of rats fed one of four diets containing either corn oil or fish oil and cellulose or pectin . Measurements were madein rats untreated with carcinogen and rats exposed to a chemical carcinogen and radiation . In rats not treated with a carcinogen , fish oil enhanced ROS , and fish oil /pectin suppressed antioxidant enzymes as compared to corn oil /cellulose . Oxidative DNA damage was inversely related to ROS in the fish oil /pectin diet and apoptosis was enhanced relative to other diets . In carcinogen treated and irradiated rats , a similar protective effect was seen with fish oil /pectin as evidenced by a reduction in oxidative DNA damage and enhancement of apoptosis . This suggests that a diet containing fish oil /pectin may protect against colon carcinogenesis by modulation of the redox environment to promote apoptosis and minimize oxidative DNA damage .
URI: http : / /hdl .handle .net /1969 .1 /3764
Date: 2006-08-16

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Effects of dietary fat and fiber on the oxidative status of the small intestine and colon of rats. Available electronically from http : / /hdl .handle .net /1969 .1 /3764 .

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