5.04.07 Prostate Health & Vitamin D, Calcitriol & PCa, PC and Sunlight, Prostate Diet Books.

Normal prostate cells are one of the sites where calcidiol converts to calcitriol. This is important to prostate health because when vitamin D levels are too low, the risk of benign prostatic hypertrophy or BPH rises. Why? Well, calcitriol slows the growth of prostate cells, keeping the gland normal in size.

One very interesting recent observation is that prostate cancer cells lose this capacity to convert calcidiol to calcitriol. And there’s now extensive evidence that calcitriol suppresses prostate cancer cell growth. When prostate cells become cancerous, they lose the capacity to manufacture calcitriol from calcidiol. Because many prostate cancer cells do not make their own calcitriol, the only way they get exposed to the compound is through calcitriol in the blood stream. This fact explains why many epidemiology studies link calcitriol to metastatic prostate cancer risk or death from prostate cancer. In fact, Giovannucci and colleagues at the Harvard School of Public Health found that the risk of metastatic prostate cancer was significantly lower if a man’s calcitriol blood level was above 40 pg/ml.

While calcitriol alone can slow prostate cancer growth in patients, this active form of vitamin D also changes the cancer in ways that make it more sensitive to other forms of cancer treatment. The most dramatic example of this is calcitriol’s impact on taxotere’s activity (Docetaxel). Adding high dose calcitriol one day prior to taxotere nearly doubles the response rate to this chemotherapy drug with very little increase in side effects.

When prostate cancer involves bone, it increases the amount of calcium deposited at the site of involvement; this increase comes at the expense of the rest of the skeleton. For this reason, men with prostate cancer often develop osteopenia or osteoporosis in the rest of their skeleton. In advanced prostate cancer, the flow of calcium into the involved bone sites can be so great that patients suffer from an abnormally low blood calcium level. The body responds to this challenge by producing parathyroid hormone, a hormone that breaks down bone to liberate enough calcium to restore normal blood levels of this mineral. Not only does this process accelerate the destruction of the bone not involved in the cancer, but also it causes bone pain. Calcitriol is a very effective treatment for an elevated parathyroid hormone level and can significantly slow bone breakdown as well as lessening the generalized bone discomfort.

For all of these reasons, I don’t think that there is any controversy about the fact that it is important for prostate cancer patients to maintain an adequate calcitriol blood level. The major controversy is how best to do this.

To read more about Vitamin D and prostate cancer, click here to purchase Vol 9 # 2.