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Diet and colon cancer: investigation into the role of cholesterol in an experimental model

Barton, Tina Patricia; (1990) Diet and colon cancer: investigation into the role of cholesterol in an experimental model. Doctoral thesis (Ph.D), UCL (University College London). Green open access

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Abstract

Epidemiological studies have implicated dietary fats in the pathogenesis of colon cancer. More specifically cholesterol in the diet has been shown to be co-carcinogenic in animals and there is indirect evidence for a similar role in man. This study investigates how cholesterol may exert such an influence using the dimethylhydrazine (DMH)-induced rat colon cancer model. Changes in serum and hepatic lipids and faecal acid and neutral sterols were measured in rats sequentially killed following DMH treatment. Rats were fed on a standard diet (41B), an elemental cholesterol-free diet Vivonex (V) or Vivonex + cholesterol (VCh). Saline-injected and dietary controls were included. The data was related to the time of sacrifice and tumour load at that time. Rats fed 41B had a significantly faster tumour development rate than those fed V whilst the VCh fed rats were intermediate. Rats with tumours had significantly higher levels of serum free cholesterol, serum phospholipids were decreased and total serum cholesterol was unchanged. Hepatic lipids were little effected by the presence of tumours but V feeding resulted in fatty liver. No changes were seen in faecal bile acids in any of the three dietary groups. Neutral sterols, in particular the ratio of cholesterol to its metabolites, coprostanol and coprostanone show an upward trend in rats with tumours but this did not reach statistical significance. The % cholesterol degradation was significantly lower in the 41B group compared to the other two whilst the VCh fed group was intermediate to and significantly different from the other two. These findings support the theory that dietary cholesterol is implicated in the pathogenesis of colon cancer. It is postulated that dietary cholesterol is diverted into the colon where it exerts its co-carcinogenic action. It is also postulated that the Vivonex diet protects via the liver and the pattern of cholesterol breakdown.

Type: Thesis (Doctoral)
Qualification: Ph.D
Title: Diet and colon cancer: investigation into the role of cholesterol in an experimental model
Open access status: An open access version is available from UCL Discovery
Language: English
Additional information: Thesis digitised by ProQuest.
Keywords: Health and environmental sciences
URI: https://discovery.ucl.ac.uk/id/eprint/10123582
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