Probiotics are living organisms claimed to provide health benefits on consumption. These generally help by improving the gut flora and the digestive system. These have been know to maintain the natural balance of microbes in the gut if at all disrupted by any illness or treatment.
Probiotics are generally sold as food than medicines, thus, they do not undergo the stringent process of regulations and development of medicines.
As such, it is difficult to know is the given probiotic has the product actually contains the bacteria stated on the food label or the product contains enough bacteria to have an effect or the bacteria are able to survive long enough to reach your gut.