&NA;Available evidence suggests that the return of an adequate amount of cereal fiber to the diet would virtually abolish constipation, and almost do away with the need for laxatives. It seems likely that it would also greatly reduce the prevalence of certain common, painful, and often fatal diseases that are characteristic of modern western civilization, and it seems possible that it might significantly reduce the incidence of large intestinal cancer. There is, on the other hand, no evidence that an increase in cereal fiber in the quantities envisaged, 2 to 6 g of crude fiber a day, could result in any conceivable harm. This is only a working hypothesis which still requires proof, but no alternative hypothesis which could satisfactorily explain these associations has been suggested. The betting odds in adopting this procedure would therefore appear to be “heads I win and tails I don't lose”—not bad odds!