There are more than 1,000 different species of bacteria living in each individual, but very few of those are actually probiotics –designed to be consumed on a daily basis in sufficient quantities to illicit a positive health effect. Although lactobacillus and bifidobacterium are among the predominant species of bacteria found naturally in the human intestines, they are not necessarily probiotics because in nature they are never consumed.
The overwhelming numbers of species found in the human digestive tract (which includes lactobacillus and bifidobacterium species) are first transferred from mother to infant during childbirth. That is the only time nature designed them to be introduced into the body. They simply don’t survive outside of the body and certainly cannot survive when re-entering the body through the digestive tract on a daily basis. These species are anaerobes – they need to live in an oxygen-free environment to survive. Nature did not design these strains to be cultivated in factory tanks, encapsulated, and then put in a bottle. That is why most lactobacillus-based probiotic products are found refrigerated in health food stores; the companies are hoping to keep the strains alive. They are very unstable when outside of the body as they are not designed by nature to leave the body and re-enter via oral consumption. Think about it, if they can’t survive at room temperature on the store shelf, how can they survive 98°F and acids in the human stomach? The answer is they simply don’t.