ACtually it would to more damage then good to the bacterias because teh good bacterias would be eliminated, allowing candidia or yeast to multiply. Though I think most of that is higher in the digestive system then the colon.

If intestinal health is your concern, why not start adding yogurt and live good bacterias to your diet. Take yeast fighters, follow the candidia restricted diet for just a week to get things balanced, abd look into FOS, a form of fiber that supports healthy bacterias.