The fact is that your organism depends on numerous good bacteria living in it. In fact, your digestion cannot function without them. Of course, there are some good ones, but also some bad ones there, and they should be well-balanced. In some cases, for example when you have to use antibiotics, most of these bacteria get destroyed, and you have to replace the good ones. Vegan probiotics supplements are designed to do exactly this.
Of course, preventing diarrhea caused by antibiotics is not the only reason for taking probiotics supplements. They make you feel better and are really good for your immune system. They improve the absorption of good substances from the food you eat and improve your digestion. Without these good bacteria, your body cannot use valuable vitamins and minerals as it should.