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

Abstract

Background: In vitro and in vivo studies suggest that selected strains of probiotic bacteria can form tight complexes with aflatoxin B 1 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 1 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. © 2006 American Society for Nutrition.