alt Hacker NewsThank you. Fixing a vitamin deficiency is an obvious benefit to physical health. But does it "cure depression"? To the extent that your depression was caused by vitamin deficiency, sure. But then didn't you just cure a vitamin deficiency? I'm sure a lot of things starting improving once your body starts getting proper nutrients after years of neglect! That doesn't indicate causality.
As far as we can tell, "depression" is a label we put onto a big bag of issues with similar symptoms, but that may require different interventions. Vitamin D deficiency may very well be or lead to one of those, and it definitely doesn't help when coexisting with something else either.