Br. Goldin et al., THE EFFECT OF LACTOBACILLUS GG ON THE INITIATION AND PROMOTION OF DMH-INDUCED INTESTINAL TUMORS IN THE RAT, Nutrition and cancer, 25(2), 1996, pp. 197-204
Male Fischer 344 rats were fed a 20% or a 5% corn oil diet and were in
jected subcutaneously with dimethylhydrazine (DMH) weekly for 16 weeks
. In addition, an approximately equal number of animals challenged wit
h DMH were fed daily, until the end of the study, 2 x 10(10) Lactobaci
llus casei subsp. rhamnosus strain GG starting three weeks before DMH
administration or after the ninth weekly injection. The feeding of the
Lactobacillus GG before and during carcinogen treatment resulted in a
significant decrease in the incidence of colon tumors and the number
of small intestinal and colon tumors pet turner-bearing animal for rat
s fed a 20% corn oil diet. This decrease in tumor incidence or number
of tumors was not seen when animals were fed the Lactobacillus after t
he ninth week of carcinogen treatment. Animals fed a 5% corn oil diet
had a lower tumor incidence and number of tumors resulting from the de
crease in dietary fat, in addition the feeding of Lactobacillus GG bef
ore the carcinogen challenge resulted in a lower incidence of colon tu
mors. These studies show that a specific strain oft. casei subsp. rham
nosus designated GG can interfere with the initiation or early promoti
onal stages of DMH-induced intestinal tumorigenesis, and this effect i
s most pronounced for animals fed a high-fat diet.