In a healthy colon, there are billions and billions of beneficial bacteria. If the conditions are right, they multiply at a proper rate to keep pace with the large numbers that are lost during feces evacuation. Antibiotics, which are strong immuno-suppressants, are prescribed for many common ailments. They not only kill the bad bugs, but also kill off all the friendly lactobacteria in the intestines, thus impairing digestion and assimilation of nutrients. When the quantity of Lactobacillus is low in the colon, partially digested food decays, producing foul gas and also bad breath. Yes, halitosis is the first indication that normal bacteria levels are terribly low.