There is some evidence that vitamin D deficiency is associated with prostate cancer: https://clincancerres.aacrjournals.org/content/20/9/2289.abstract https://c

There is some evidence that vitamin D deficiency is associated with prostate cancer: https://clincancerres.aacrjournals.org/content/20/9/2289.abstract https://clincancerres.aacrjournals.org/content/20/9/2289.abs... There are a number of other studies on this. From what little I've read, if the effect is real,it seems the it is relatively weak, but still worth doing.