This logic tends to be a generally accepted urban legend (at least in my opinion). Most references/discussions of treatment with an anti-diarrhea medication almost always carries the suggestion to delay the use of such medication to allow the body to flush out the agent. While I cannot say that 100% of diarrhea is not a body’s defense mechanism, I think I can safely say it is not a major defense mechanism. The mechanism of diarrhea is more likely caused by the direct pathological (disease causing) effect the organism is having on the body, either though the production of toxins (exo- and endo-) and/or the physical invasion of intestinal mucosa.

Many of these organisms invade (viruses essential invade and take over a cell’s mechanics to produce more virus) or closely associate with the intestinal mucosa. Flushing (diarrhea) will likely have little effect on their populations. Two significant factors in the non-medicated treatment of diarrhea, is the body’s ability to mount an immune response and being out-competed (in the case of bacterial diarrhea) by the other intestinal flora. A relatively healthily individual is capable of mounting an immune response quicker and with greater vigor than a run-down individual. Maintaining hydration and vigor is critical, in combating diarrhea. Likewise, with respect to bacterial diarrhea is maintaining a healthy population of beneficial bacteria. Personally, I encourage the use of pro-biotics (taking a bacterial supplement or eating active culture yogurt / keefer) to maintain a healthy and pathogenic resistant intestinal tract. The best example for supporting this view is in comparing the relative resistance of axenic (germ-free) mice vs. mice with a normal population of intestinal flora. It takes a single Salmonella organism in the axenic mouse to establish an infection whereas in the intestinally normalized mice it takes in excess of 10^5 Salmonella organisms to establish an infection.

Here is a link to one article examining the mechanism of bacterial diarrhea:

Surface Structures of Escherichia coli That Produce Diarrhea by a Variety of Enteropathic Mechanisms


Pete