Suberized plant cell walls suppress formation of heterocyclic amine-induced aberrant crypts in a rat model

Dietary fibre is believed to protect against a range of Western diseases, including colorectal cancer. Whole plant cell walls make up most of the dietary fibre in Western diets, but their role in disease protection has rarely been studied. At least in vitro, suberized plant cell walls possess novel properties that suggest they could have exceptional potential for cancer protection. Our aim was to test in a rat model the abilities of suberized cell walls from potato skins and commercial cork to decrease gastrointestinal transit time and to protect against the development of aberrant crypts, an early marker of colon cancer. Groups of six rats were fed a modified AIN-76(TM) diet as the control diet and this diet supplemented with 5% dietary fibre from the following sources: commercial cork, commercial-cork cell walls and potato-skin cell walls. A diet supplemented with wheat bran was used as a positive control. The colon carcinogen IQ (2-amino-3-methylimidazo[4,5-f]quinoline) was administered for 3 weeks and after another 12 weeks the number of aberrant crypts determined. Transit times were determined after feeding the diets for 4 weeks. Compared with rats fed the control diet, rats fed diets supplemented with the suberized cell-wall preparations had decreased transit times and had significantly fewer aberrant crypts, with no aberrant crypt foci containing four or more crypts. The diets supplemented with suberized cell walls were more effective than the diet supplemented with wheat bran. We conclude that suberized and lignified cell walls, but particularly suberized, may play an important role in protection against Western diseases, including colorectal cancer. Failure to distinguish suberized and lignified plant cell walls from other sources of non-starch polysaccharides may provide a major limitation in current assessments of the role of dietary fibre in preventing colorectal cancer in humans. (C) 1998 Elsevier Science Ireland Ltd. All rights reserved.