Vitamin D3 made a huge difference for me.
The multivitamins have for too little D3 to make a difference. 2000 I.U. minimum a day is what worked for me.
It is the only vitamin I ever taken that made an immediate and substantial change to my health. Unfortunately I went probably 25 years of my life seriously deficient of it. My skin is very light and I can’t take the sun. I don’t tan, just burn. I had odd immune system related health problems I thought I was going to have to live with the rest of my life, and they literally went away after taking D3.
I became interested in vitamin D deficiency five years ago when I read this article. I posted it on Free Republic at that time.
Before I started taking 'higher' doses of vitamin D, I would have bronchitis at least once and sometimes twice a winter requiring a doctors visit...Now, no bronchitis in at least four years.