Probiotic supplementation reduces a biomarker for increased risk of liver cancer in young men from Southern China

Background: In vitro and in vivo studies suggest that selected strains of probiotic bacteria can form tight complexes with aflatoxin B, and other carcinogens. Objective: The aim of the present study was to determine whether administration of probiotic bacteria could block the intestinal absorption of aflatoxin B, and thereby lead to reduced urinary excretion of aflatoxin B-1-N-7-guanine (AFB-N-7-guanine), a marker for a biologically effective dose of aflatoxin exposure. Elevated urinary excretion of this aflatoxin-DNA adduct is associated with an increased risk of liver cancer. Design: Ninety healthy young men from Guangzhou, China, were randomly assigned to 2 groups; one group received a mixture of Lactobacillus rhamnosus LC705 and Propionibacterium freudenreichii subsp. shermanii strains 2 times/d for 5 wk, and the other group received a placebo preparation. The subjects provided 4 urine samples: at baseline, at 3 and 5 wk after starting the supplementation, and at the end of the 5-wk postintervention period. Results: The percentage of samples with negative AFB-N-7-guanine values tended to be higher in the probiotic group than in the placebo group during the 5-wk intervention period (odds ratio: 2.63, P = 0.052), and a statistically significant decrease in the concentration of urinary AFB-N-7-guanine was observed in the probiotic group. The reduction was 36% at week 3 and 55% at week 5. The geometric means for the probiotic and placebo groups were 0.24 and 0.49 ng AFB-N-7-guanine/mL, respectively, during the intervention period (P = 0.005). Conclusion: A probiotic supplement reduces the biologically effective dose of aflatoxin exposure and may thereby offer an effective dietary approach to decrease the risk of liver cancer.