Dietary fiber-mediated mechanisms in carcinogenesis
Klurfeld, D.M.
Cancer Research 52(7 Suppl): 2055s-2059s
1992
ISSN/ISBN: 0008-5472 PMID: 1311988 Document Number: 399477
A review. Dietary fibre may affect the development of cancers of the gastrointestinal tract and the breast. The biological intermediates studied most have been faecal bile acids; both human and animal studies suggest a tumour-promoting role of bile acids in the development of colon tumours, although there are conflicting data from human studies. Short-chain fatty acids are major fermentation products of bacterial degradation of dietary fibre. If short-chain fatty acids explained the tumour-inhibiting properties of dietary fibre, the readily fermentable fibres such as guar and pectin would be more protective than cellulose and wheat bran, which has not been observed. Because these 2 hypotheses do not adequately explain modulation of tumour growth of dietary fibre, investigation of other intermediates is indicated. These included physical characteristics of the faeces, such as abrasiveness; intestinal microflora; aqueous-phase bile acids, which may represent the bioavailable pool; alterations in mucins; mutagenicity of intestinal contents; alterations in mucosal cytokinetics; activities of enzymes, such as ornithine decarboxylase or aryl hydrocarbon hydroxylase; neurogenic effects caused by changes in intestinal bulk of short-chain fatty acids; gut hormones or other peptide growth factors (local or systemic)l enterophepatic circulation of hormones; transit time; pH; or decreased availability of total dietary energy.