Prostate cancer is the second most common type of cancer diagnosis in men—the most common being skin cancer. David Feldman, MD, of Stanford University, has been studying how vitamin D and soy may slow or stop the growth of prostate cancer.
In an American Institute for Cancer Research newsletter, Dr. Feldman explains that vitamin D isn’t really a vitamin. “Vitamin D is a precursor to a potent hormone called calcitriol that regulates hundreds of genes in most tissue of he body. Taking vitamin D is more like taking a substance that the body then converts to an active drug.”
Calcitriol helps the body absorb calcium, which is why it’s often in calcium supplements. Calcitriol is has anti-cancer effects on certain pathways involved in the growth of cancer cells. Vitamin D is being studied for its potential to reduce the risk for prostate, breast and colorectal cancers.
Dr. Feldman cautions men from trying to find the right amount of vitamin D and soy without the help of their medical team. While the combination of vitamin D and soy is being studied to see if it protects against the development or progression of prostate cancer, the combination can have significant and toxic side effects (including fatality).
By getting a blood test, your doctor will know how much calcium and vitamin D is in your body, and can then suggest proper doses of supplements. Dr. Feldman and his colleagues are extending their studies through a new American Institute for Cancer Research-funded study.
Until we know the findings are solid, get your calcium and vitamin D in reasonable doses, unless otherwise told to do so, increase the amounts through foods.
A note about soy to women: If you’ve had family members with estrogen receptive cancer —if you don’t know the answer, but know someone in the family had breast or ovarian cancer, I highly recommend women avoid soy. I’m not a doctor. I’m a woman who had estrogen receptive breast cancer, and a reoccurrence of it. I tested positive for being high risk for ovarian cancer and had my ovaries removed to prevent an estrogen receptive site from having the opportunity to host cancer. I’ve been told to not take any soy supplements. Talk with your oncologist.