Probiotics are good for people with stomach aches. Is there a medical risk that regular consumption of probiotics without exceeding daily dosage will cause bad effects like addiction or harm to health over the long-term? Probiotics are actually bacteria and bacteria sounds harmful.
If we consider that the numbers of bacteria far exceed that of human cells then you will realise that bacteria are not necessarily harmful.
Addictions require some type of immediate positive reinforcement eg. through opioid receptors or cannabinoid receptors and since probiotic organisms are usually mixed in with food, this seems highly unlikely to cause an addiction.
Furthermore, probiotics have been taken in one form or another for millennia; their use is not new, and they often have beneficial effect on human health.
It became clear that intestinal microflora had metabolic functions, such as fermenting indigestible dietary residues and endogenous mucus, saving of energy, production of vitamin K, and absorption of ions (O’Sullivan et al., 1992). Probiotics have roles in epithelial cell proliferation and differentiation, and the development and the homeostasis of the immune system (Cammarota et al., 2009). Probiotics are not an invention but existed in our traditional foods such as beverages, salty fishes, yogurt, different types of cheeses and so on since olden times (Amara, 2012). Such food structures contain different types of useful bacteria. It might be that the first real use of food containing Probiotics was fermented milk (Hosono, 1992). Humans learned that fermented milk has a good taste. Later they learned how to convert it into cheese, yogurt and so on (Metchnikoff and Mitchell, 1910; Metchnikoff, 2004; Amara, 2012). Before the discovery of the microscope, humans knew how to prepare different types of milk products with different tastes and structures (Amara, 2012). This is a result of the action of different microbial reactions induced by different microbes (Bourdichon et al., 2012).