Probiotics

Probiotics seems to be the new buzz word.  Capsules of "good bacteria" are available in drug stores and even in supermarkets.  There are very few clinical studies with respect to probiotic bacteria and whether injesting them have a benefical effect.  Hundreds of species of bactera number to multi trillions of bacteria.  These bacteria live in a balance and a delicate ecosystem.  If we decrease the numbers of a certain specie (using antibiotics) we may cause others to increase in numbers, this alters that fine ecosystem resulting in disease.  What happens if we increase the numbers of a certain specie using probiotics?