ABSTRACT
Calcium from food was a somewhat better predictor of colon cancer risk than total calcium, which included calcium from food supplements. Calcium from food supplements was slightly but not significantly protective, both before and after adjustment for fat and the other risk factors. Cases were patients with histologically confirmed invasive adenocarcinoma of the colon. They were prospectively identified by the population-based tumor registry covering all residents of Los Angeles County. Most calcium in dairy products is in the form of calcium caseinate, which is readily ionized and therefore available for either absorption or for binding with fatty acids in the lumen of the GI tract. Like calcium, total vitamin D intake did not predict risk as a univariate variable but became protective after adjustment for total fat. Estimates of absorbed calcium rise rapidly as a function of intake when intakes are low, but after intakes of about 500 mg per day, absorbed calcium levels rise more slowly.
