| dc.description.abstract | The effect of dietary beta carotene on colon carcinogenesis
Induced by 1,2-dimethylhydrazine «DMH) CAS: 540-73-81
was studied in female inbred Swiss Webster (ICR) mice. At age
10 weeks and continuing throughout the experiment, mice received
diets consisting mainly of natural foods (laboratory chow)
and containing 2 or 22 mg p-carotene/kg. At age 15 weeks they
received 7 weekly sc injections of DMH (total dose: 196 mg
DMH-diHCI/kg body wt). When autopsied 31 weeks after the first
DMH injection, the incidence (percent of mice with tumors) and
multiplicity (number of tumors/tumor-bearing mouse) of colon
tumors were reduced by half in the mice supplemented with beta carotene.
There was a much greater decrease in adenocarcinomas
than in adenomas. Mice observed for 13 additional weeks revealed
that the mortality rate, due largely or wholly to colon cancer, was
only about half in supplemented mice. Mice sacrificed 12 weeks
after the first dose of DMH (Le., well before tumors appeared)
showed mild colon mucosal hyperplasia. p-Carotene supplementation,
however, did not alter this, Indicating that the protective effect
against colon cancer may have occurred at a late stage of
carcinogenesis. | en |
