In response to a now-deleted post: all antibiotics
Post# of 72440
No one is going to deny someone a life-saving antibiotic because that antibiotic wipes out good bacteria too. Why would anyone think it was a good idea to risk the life of someone because of a transient, fixable problem with death of gut bacteria?
In fact, there is great disagreement about what the "ideal" mix of beneficial bacteria is, and there is very little hard evidence from clinical trials. There was one clinical trial that identified a bacterium that seemed to be present in many thin and normal-weight people, but that was lacking in obese people. However much more needs to be done in this field, and there is no generally accepted consensus by scientists as yet.
There are lots of companies out there trying to sell stuff to gullible people by making all kinds of dubious claims and pseudo-scientific rationales for why you should take their vitamins or use their products. Probiotics and prebiotics can be beneficial, but anything you read should be taken with a grain of salt. Or at least a dose of probiotics by a reputable manufacturere.