Influence of dietary calcium and vitamin D on colon epithelial cell proliferation and 1,2-dimethylhydrazine-induced colon carcinogenesis in rats fed high fat diets.
We investigated whether increased levels of dietary calcium and vitamin D could inhibit colon carcinogenesis in rats injected with a single dose of 1,2-dimethylhydrazine. Rats were given a single subcutaneous injection (200 mg/kg body wt) 2 wk before they were fed purified diets containing 20% fat for 32 wk. Diets contained one of three levels of calcium (5, 10 or 15 g/kg diet) as calcium gluconate and one of three levels of vitamin D (0.025, 0.05 or 0.1 mg/kg diet) as cholecalciferol in a 3 x 3 factorial design. Rats receiving the highest level of vitamin D had greater plasma concentrations of 25-hydroxy-vitamin D. Autoradiographic examination of [3H]thymidine-treated rats demonstrated that a higher dietary level of calcium as well as higher levels of vitamin D significantly affected cellular kinetic indices. The total tumor incidence and tumor incidence in the distal colon was 45% lower in rats fed the highest level of both calcium and vitamin D compared with the other eight groups, although this decrease was not statistically significant (P = 0.12). The possible importance of these observations is discussed.
Beaty
M M
MM
Department of Nutrition and Food Science, A. B. Chandler Hospital, Lexington, KY.
Lee
E Y
EY
Glauert
H P
HP
D019813:1,2-Dimethylhydrazine; D000818:Animals; D001345:Autoradiography; D001835:Body Weight / Q000187:drug effects; D002112:Calcifediol / Q000097:blood; D002136:Calcium, Dietary / Q000494:pharmacology*; D002273:Carcinogens / Q000494:pharmacology; D002455:Cell Division / Q000187:drug effects; D003106:Colon / Q000166:cytology / Q000187:drug effects; D003110:Colonic Neoplasms / Q000139:chemically induced / Q000517:prevention & control*; D004041:Dietary Fats / Q000494:pharmacology*; D004127:Dimethylhydrazines; D004847:Epithelial Cells; D004848:Epithelium / Q000187:drug effects; D008297:Male; D010758:Phosphorus / Q000097:blood; D051381:Rats; D011916:Rats, Inbred F344; D014807:Vitamin D / Q000494:pharmacology*
D002136:Calcium, Dietary; D002273:Carcinogens; D004041:Dietary Fats; D004127:Dimethylhydrazines; D014807:Vitamin D; D010758:Phosphorus; D019813:1,2-Dimethylhydrazine; D002112:Calcifediol