Bread -> Baker's Yeast

Hi everyone, I've just joined the forums and noticed that a lot of you have quite a lot of knowledge under your belts! So, here's the question, does anyone know what risks are associated with eating bread (which contains baker's yeast)? I recall hearing about some studies between Japanese and American women saying that Japanese women had a far lower chance of getting breast cancer, which is mot likely because they have a far lesser yeast intake. Does anyone have an more information?