Based on the ability of the probiotics in the gut microflora modification, they can have the beneficial effects on diseases in the short and/or the long term. In previous study, we revealed that unlike Bifidobacterium bifidum, the amount of Lactobacillus acidophilus remained almost unchanged in mice gut microflora in the long term, indicating more stability of L. acidophilus than B. bifidum which can be used to prevent some incurable diseases such as cancer. Thirty-eight male BALB/c mice were divided into four groups, control, azoxymethane (AOM), L. acidophilus, and B. bifidum probiotics, to evaluate the protective effects of the probiotics on AOM-induced mouse colon cancer. Except for the control group, the rest of the animals were weekly given AOM (15 mg/kg, s.c) in three consecutive weeks. Colon lesion incidence was 74% in the AOM group in comparison with the control (0%) (P < 0.05). The lesions were varied from mild to severe dysplasia and colonic adenocarcinoma. Administration of the probiotics inhibited the incidence of colonic lesions by about 57% in L. acidophilus (P < 0.05) and 27% in B. bifidum (P > 0.05) compared to the AOM group. The serum levels of CEA and CA19-9 tumor markers were significantly decreased in L. acidophilus in comparison with the AOM group (P < 0.05). Moreover, the serum levels of IFN-γ and IL-10 and the number of CD4 and CD8 cells were significantly increased in L. acidophilus compared to AOM (P < 0.05). Our study highlighted the more potential effects of L. acidophilus probiotic than B. bifidum on mouse colon cancer.

Background/aim: Thirty male BALB/c mice were equally divided into three groups: control, L. acidophilus, and B. bifidum for the assessment of the probiotics' stability in the gut microflora.Materials and methods: First, the gut microflora of the mice was checked every 3 days (days 3, 6, 9, and 12) without probiotic consumption, and then the mice were daily given orally 1.5 g of probiotics in 30 cc of drinking water. The consumption of probiotics was then stopped for recovery and then the consumption continued for 5 months.Results: On day 9 after the consumption of the probiotics, L. acidophilus and B. bifidum were significantly increased from 4% to 83% and from 1% to 61%, respectively. L. acidophilus count showed no significant decrease at the end of 5 months compared to day 9 of probiotic consumption (74%), but B. bifidum count was dramatically decreased to 45% and 36% at the end of 1 and 5 months, respectively. Conclusion:Our results revealed that, unlike B. bifidum, the amount of L. acidophilus remained almost unchanged in the long term, indicating more stability of L. acidophilus than B. bifidum in the gut microflora.