The researchers found that the intakes of various foods and nutrients could influence the risk of bladder cancer, because most metabolites are excreted through the urinary bladder.
With regard to dietary factors, consumption of milk and other dairy foods could potentially reduce the risk of bladder cancer.
82,002 Swedish women and men who were cancer-free and who completed a 96-item food-frequency questionnaire in 1997 were evaluated. Incident cases of bladder cancer were identified in the Swedish cancer registries. 485 participants were diagnosed with bladder cancer during a mean follow-up of 9.4 years.
Total dairy intake was not significantly associated with risk of bladder cancer, however, a statistically significant inverse association was observed for the intake of cultured milk (sour milk and yogurt).
The intake of milk or cheese was not associated with bladder cancer risk.
Cultured milk products contain lactic acid bacteria, which have been shown to suppress bladder carcinogenesis in rodents. The mechanism accounting for the antitumor effect of lactic acid bacteria is not clear, but it may be related to modulation of the immune system.
In addition, oral administration of lactic acid bacteria has been shown to suppress food-derived urinary mutagenicity in humans, thus possibly reducing bladder carcinogenesis.
The researchers conclude that that a high intake of cultured milk may
lower the risk of developing bladder cancer.