I am no expert, but you need healthy bacteria for the colon to work properly. Healthy bacteria keeps candida and other stuff in order.
I've had all kinds of bowel issues in the past including constipation and loose bowels. Since I started eating home made kefir with berries every morning and every night I've virtually had no issues whatsover.
It's also cheap. People will ship you the grains for the price of an envelope and some stamps.