The incidence of lactose malabsorption in ulcerative colitis

120 Danish patients with ulcerative colitis, admitted consecutively to a Department of Gastroenterology, were investigated for lactose malabsorption. The prevalence was 9.2 percent, which is not significantly higher than that in a mixed Danish gastroenterological material, There was no difference in distribution according to age and sex, and the incidence was not correlated to the severity of the ulcerative colitis. The possible reasons for the wide variation in the incidence of lactose malabsorption in materials of patients with ulcerative colitis are discussed, and it is concluded that the main cause must be that the materials with the highest incidence include patients of races and ethnic groups in which lactose malabsorption is a common finding.