Editor,—It is interesting that Macrae et al (Gut 1997;41:239–45) found that unprocessed wheat bran had a greater effect than processed bran or oat bran on the reduction of labelled cells in the top two fifths of rectal epithelial crypts. There is evidence that wheat bran may have effects on other mucosal surfaces, particularly that of the duodenum. The prevalence of duodenal ulceration is lower in India in the unrefined wheat eating areas of the Punjab than in the polished rice eating areas of the South.1-3 Our experimental work on several animal models has shown that wheat bran is protective against peptic ulceration and that this protection is linked with its lipid content.4 ,5 The evidence so far suggests that this effect may be related to a unique combination of lipids in certain cereal fibres and not to a particular type of fibre.