Taking vitamin D daily did wonders for my psoriasis. Over the years it had gotten to the point where I was breaking out in patches all over my body, and only getting worse as time went on. I went from like 2% coverage to 20%.
Started taking vitamin D and am now back at 2% (where it has sat for 4 years now since I started).
I had an outbreak of erythrodermic psoriasis (usually just have mild plaque psoriasis) over the winter and had it all over my trunk, arms and legs - approx 80% coverage. Luckily it wasn't as severe as it could be (no hospitalisation necessary), but I had a lot of trouble with body heat regulation for a while.
I ended up using topical steroids which cleared it up remarkably quickly, but am now trying to reduce my usage of that (stopping steroids can be a trigger for erythrodermic psoriasis) which has led to it becoming more pronounced again.
Started taking vitamin D and am now back at 2% (where it has sat for 4 years now since I started).