Calcium carbonate suppresses haem toxicity markers withoutcalcium phosphate side effects on colon carcinogenesis
2011
Salah Eldin Allam, Ossama | Bahuaud, Diane | Tache, Sylviane | Naud, Nathalie | Pierre, Fabrice
Red meat intake is associated with increased risk of colorectal cancer. We have previously shownthat haemin, haemoglobin and red meat promote carcinogen-induced preneoplastic lesions,aberrant crypt foci, in the colon of rats. We have also shown that dietary calcium phosphateinhibits haemin-induced promotion, and normalizes faecal lipoperoxides and cytotoxicity.Unexpectedly, high-calcium phosphate control diet-fed rats had more preneoplastic lesions in thecolon than low-calcium control diet-fed rats. The present study was designed to find a calciumsupplementation with no adverse effect, by testing several doses and types of calcium salts. One invitro study and two short-term studies in rats identified calcium carbonate as the most effectivecalcium salt to bind haem in vitro and to decrease faecal biomarkers previously associated withincreased carcinogenesis: faecal water cytotoxicity, thiobarbituric acid reactive substances. A longterm carcinogenesis study in dimethylhydrazine-injected rats demonstrated that a diet containing100 μmol/g calcium carbonate did not promote aberrant crypt foci, in contrast with previouslytested calcium phosphate diet. The results suggest that calcium carbonate, and not calciumphosphate, should be used to reduce haem-associated colorectal cancer risk in meat-eaters. Theysupport the concept that the nature of the associated anion to a protective metal ion is importantfor chemoprevention.
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