I think the thing about vitamin B is that stress uses up your B vitamins, so they assume that depression stresses you, and you need extra vitamin B. I find that MSM helps me.

I also forget to take my vitamins when I'm depressed, so I don't know if they help me or not. I know I have a little more energy after I've taken them regularly for awhile, and I sleep better. I'm not on meds, so don't know about that.