They probably won't help you unless your depression is very minor. What is true is that much research is focusing on the connection between probiotics and mental health, and that if you've had a die-off of probiotics due to, say, the use of antibiotics, it can cause mental illness. The problems is, which ones do you need and are they available as a supplement? Now, anyone can go to the best local health food store and buy the best probiotic formula from the refrigerated section of the supplement department, and it would only help your overall health, so if you want to try it, it's risk-free -- if your body doesn't need them, they just travel on through and if your body does need them, they will move into your intestinal tract and do what they do. One of the things they do, by the way, that involves mental health is produce B vitamins, essential to good mental health. As this research progresses, the solution will more likely be something like fecal transplants to fix the whole system unless somehow they discover one or two probiotics among the tons of different ones in our systems that help with this problem. Most of the supplements we take are better known for helping with fungal infections and digestive problems. But again, no loss in trying.