ABSTRACT
Most of the studies in humans were clinical trials in which the effect of short-term calcium supplementation was studied. The germinal study, using proliferation of the colonic epithelium as a biomarker of response, was that of M. Lipkin and H. L. Newmark. Stronger but indirect evidence for the protective role of dietary calcium came from animal studies. Diets high in bile acids and/or fat resulted in large bowel mucosal damage and, therefore, increased epithelial proliferation. This could be reduced by adding calcium or vitamin D to the diet, even in the presence of a carcinogen. An intermediate possible biomarker that is being used is the measurement of epithelial proliferation. Its assessment has been made easier and quicker by the use of bromodeoxyuridine labeling. The newer immunohistochemistry test of proliferating cell nuclear antigen is even faster. Thus, these latter 2 tests should be useful for measurement of risk and response to calcium intervention.
