FLAVONOID GLUCOSIDES ARE HYDROLYZED AND THUS ACTIVATED IN THE ORAL CAVITY
You can add this one to the damaging effects of antibiotics. Always irks me when all the concern about antibiotic overuse focuses on antibiotic resistance, when the real, long term damage comes from destroying normal bacterial flora.
This study finds that the bacterial conversion of certain flavonoids (genistein from soy and quercetin from onions) can occur as early as the oral cavity, thus producing more effective compounds to protect the oral cavity from diseases such as cancer. So, while antibiotics may not cause cancer, they may remove some of the potential protective effects given to us by foods. We have seen an association with antibiotic use and breast cancer recently as well.