The disaccharide lactulose (β-D-galactopyranosyl-(1-4)-D-fructofuranose) is thought to be poorly hydrolized by intestinal enzymes but is broken down by microorganisms in the colon. Thus lactulose shares with pectin similar characteristics . Lactulose is used in the food industry and in the treatment of constipation. There is preliminary evidence that dietary lactulose (5%, w/w) causes increased cocentrations of serum and her cholesterol in rats when compared with pectin . This paper describes dose-response relationships between dietary lactulose and cholesterol in either serum or liver.