PROTECTIVE ROLE OF LACTULOSE IN INTESTINAL CARCINOGENESIS

Primary bile acids are converted to carcinogenic secondary bile acids by colonic bacteria when the colonic pH is high. Therefore acidificati on of the luminal contents may reduce the cancer risk. The ability of lactulose to reduce colonic pH, secondary bile acid production, mucosa crypt cell production rate and tumour formation was measured in a rat model of intestinal carcinogenesis. Eighty Wistar rats were divided i nto four groups receiving normal diet alone or with lactulose, azoxyme thane or both azoxymethane and lactulose. The addition of lactulose wa s associated with a significant fall in small intestinal and colonic p H. Lactulose was associated with a sharp rise in the secondary to prim ary bile acid ratio. The crypt cell production rate fell significantly with lactulose. The addition of lactulose was associated with a signi ficantly reduced tumour yield in small intestine but not in colon. Lac tulose therefore can reduce this is of no value in humans at risk of d eveloping colorectal carcinoma.