The vitamin appears to reduce inflammation in the prostate gland, and this slows the growth of the cancer or even reverses it, say scientists at the Medical University of South Carolina.
It could be the perfect way to support the period of 'watchful waiting' when men with low-grade or less aggressive forms of prostate cancer regularly monitor the progress of the cancer. Only aggressive and high-grade cancers are treated-either with radiotherapy or radical surgery-as side-effects usually interfere dramatically with quality of life, and can make the man incontinent or impotent, or both.
In an experiment with 37 men who had chosen to have surgery on their low-grade cancers, half were given 4,000 IUs (around 1200 mcg) of Vitamin D a day, and the rest had a placebo. After 60 days, the tumours in those taking the vitamin had reduced in size, whereas they had grown or stayed the same in those given the placebo.
The researchers say that they treated the men with modest levels of vitamin D. The body can make up to 20,000 IUs (around 6000 mcgs) every day just from exposure to strong sunlight.
(Source: Proceedings of the American Chemical Society, March 22, 2015)