Effects of dietary fiber, fat, and carcinogen on the early stages of colon carcinogenesis in rats /
Colon cancer is the second leading cause of death from cancer and is the cancer considered to be most affected by diet. Among dietary factors, dietary fibers and fats are most linked to colon tumor development. Poorly fermentable fibers, such as cellulose or n-3 fatty acids (rich in fish oil) are be...
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| Format: | Thesis Book |
| Language: | English |
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[Place of publication not identified] :
[publisher not identified] ;
1999.
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| Subjects: | |
| Online Access: | http://proxy.library.tamu.edu/login?url=http://proquest.umi.com/pqdweb?did=731681481&sid=1&Fmt=2&clientId=2945&RQT=309&VName=PQD |
| Summary: | Colon cancer is the second leading cause of death from cancer and is the cancer considered to be most affected by diet. Among dietary factors, dietary fibers and fats are most linked to colon tumor development. Poorly fermentable fibers, such as cellulose or n-3 fatty acids (rich in fish oil) are believed to be protective compared to highly fermentable fibers such as pectin or n-6 fatty acids (rich in corn oil), respectively. Most studies investigating the elect of diet on colon tumorigenesis and prevention have focused on the middle or late stages of colon carcinogenesis. Thus, the purpose of this study is to determine the effect of different dietary fibers or fats on colon tumorigenesis in the early stage of colon carcinogenesis, and to elucidate the possible mechanisms. Cellulose supplementation increased differentiation and apostasis in the proximal colon and decreased cell proliferation in the distal colon compared to pectin supplementation in the 6 wk post carcinogen injection study. In the initiation study (within 12 h post carcinogen injection), pectin with fish oil or corn oil was selected because the protective effect of fish oil was enhanced when pectin was in the diet (Chang et al. 1997). Dietary fish oil increased DNA repair enzyme expression in the proximal colon, and decreased DNA damage by an increase of apostasis in the distal colon compared to the corn oil diet within 12 h post carcinogen injection. The enhancing elect of dietary fish oil on apostasis may be, in part, through the lowering of bcl-2 expression in the top 1/3 of the crypt of the distal colon. Azoxymethane-induced DNA damage was similar in rat proximal and distal colon, but the response (apoptosis and DNA repair enzyme expression) to the damage was greater in the distal colon compared to the proximal colon. These results suggest that dietary fish oil ants as an anticarcinogen by increasing targeted apostasis in the distal colon and thus decreasing DNA adduct levels. In conclusion, dietary fibers or fats may modulate colon tumorigenesis at the early stages of colon carcinogenesis. |
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| Item Description: | Vita. "Major Subject: Nutrition". |
| Physical Description: | xiv, 315 leaves : illustrations ; 28 cm. Issued also on microfiche from University Microfilm Inc. |
| Bibliography: | Includes bibliographical references (leaves 181-221). |