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 diseas es, including colorectal cancer. Whole plant cell walls make up most o f the dietary fibre in Western diets, but their role in disease protec tion has rarely been studied. At least in vitro, suberized plant cell walls possess novel properties that suggest they could have exceptiona l 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 followi ng sources: commercial cork, commercial-cork cell walls and potato-ski n cell walls. A diet supplemented with wheat bran was used as a positi ve control. The colon carcinogen IQ (2-amino-3-methylimidazo[4,5-f]qui noline) was administered for 3 weeks and after another 12 weeks the nu mber of aberrant crypts determined. Transit times were determined afte r feeding the diets for 4 weeks. Compared with rats fed the control di et, rats fed diets supplemented with the suberized cell-wall preparati ons had decreased transit times and had significantly fewer aberrant c rypts, 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 importa nt role in protection against Western diseases, including colorectal c ancer. 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 prev enting colorectal cancer in humans. (C) 1998 Elsevier Science Ireland Ltd. All rights reserved.