Habitual Intake of Lactic Acid Bacteria and Risk Reduction of Bladder Cancer

<i>Introduction:</i> A kind of lactic acid bacteria, <i>Lactobacillus casei</i> strain Shirota, shows antitumor activity in experimental animals. One clinical trial using <i>L. casei</i> showed a significant decrease in the recurrence of superficial bladder cancer. So, to assess the preventive effect of the intake of <i>L. casei</i>, widely taken as fermented milk products in Japan, against bladder cancer, we conducted a case-control study. <i>Methods:</i> A total of 180 cases (mean age: 67 years, SD 10) were selected from 7 hospitals, and 445 population-based controls matched by gender and age were also selected. Interviewers asked them 81 items. The conditional logistic regression was used to estimate adjusted odds ratios (OR). <i>Results:</i> The OR of smoking was 1.61 (95% confidence interval: 1.10–2.36). Those of previous (10–15 years ago) intake of fermented milk products were 0.46 (0.27–0.79) for 1–2 times/week and 0.61 (0.38–0.99) for 3–4 or more times/week, respectively. <i>Conclusion:</i> It was strongly suggested that the habitual intake of lactic acid bacteria reduces the risk of bladder cancer.