While research suggests that multi-strain probiotics seem to bring greater digestive benefits and digestive distress relief, single strain or lower strain probiotics can be especially beneficial for those who do not tolerate higher levels well and for those that may need a specific targeted strain for a certain condition. One advantage of a single strain probiotic is that they allow users to pick and choose which healthy bacteria to increase. Everyone has a different ecosystem of bacteria, and sometimes there is a deficiency or total lack of certain beneficial bacteria that a single strain can help replenish. You can read more about which strains support which conditions here.