Actually, I am asked this question almost daily. Although, I don't discount the possibility for some benefits from taking probiotic supplements, I have yet to see someone who actually improved or cured the digestive problems for which they are recommended. Taking probiotics, in my opionion, is more of a bandaid that may provide some temporary relief or support to the intestinal flora, but it doesn't realy address the core issues of the disturbed flora. For one thing, lack of bile secretion naturally leads to over-population of destructive bacteria due to the increased need for decomposing excessive waste matter. Another simple cause for a disturbed flora is eating the main meal of the day in the evening when secretions digestive enzymes, HCL and bile are naturally at the lowest. There are many other reasons contributing to such as situation, which I mentioned in my book, Timeless Secrets of Health & Rejuvenation. Most medical drugs, including antibiotics affect digestive functions and lead to destruction of beneficial bacteria. Yeast overgrowth is not a disease, it is survival mechanism to deal with the acidic waste and toxic environment caused by an overtaxed digestive system. Once the liver and instestines have been cleaned out properly, and are supported through a healthy, balanced diet and lifestyle, candida bacteria will retreat to where they belong, the mucus lining of the GI tract. The return to the normal pH of the GI tract, which requires a clean environment, will help restore the normal population of probiotic bacteria. Implanting or ingesting large amounts of probiotic bacteria in a filthy, acidified intestinal milieu will not improve the pH. Therefore, most of these probiotic bacteria will quickly perish, leaving billions of corpses behind. A colon that is cleansed during a colonic will have very few bacteria left. But the appendix will quickly breed new ones and within 48 hours have restored normal bacteria levels, unless the new foods passing through the intestines change that again. Nobody can really know the exact normal ratio, as this depends on body type and diet.
If taking probiotics makes you feel better, by all means, take them. In the long term, though, it is best to stimulate its own production of these bacteria. Those people who had their appendix removed, need to take extra care to keep their intestines clean through liver and colon cleansing and a balanced diet/lifestyle.