For decades, scientists have been trying to increase the amount of activated vitamin D in cancer cells, in the hope that it will slow cancer’s growth, without causing high blood calcium at the same time. In many ways, activated vitamin D is the ideal anticancer drug, as it forces cells to die when they are supposed to do so (apoptosis) and it increases specialization (differentiation) of cells, unlike cancer cells that try to avoid dying and are often highly undifferentiated.
Although many cancers destroy the vitamin D system as soon as they can, not all cancers do. That is, some cancer cells retain both the enzymes and the receptors needed for the vitamin D system to work. Therefore, beginning in the 1980s, the search was on for an activated vitamin D-like molecule that would go inside cancer cells but not cause high blood calcium at the same time.
The struggle to increase activated vitamin D in cancer cells has led scientists to develop several hundred analogues (variations to the molecule that allow scientists to patent it) of activated vitamin D. However, all analogues to date are problematic because they still cause high blood calcium. Furthermore, they do not get inside cancer cells to the degree needed to kick the vitamin D system into high gear. If they do, blood calcium levels become dangerously high.
At the April 2012 meeting of the American Association for Cancer Research, Professor Reinhold Vieth and his group reported taking another approach. Instead of giving activated vitamin D or its analogues, they simply gave increasing doses of plain old vitamin D in hopes the cancer cells would take up 25(OH)D and make high amounts of activated vitamin D inside the cell.
They first randomized 66 men scheduled for removal of a cancerous prostate (radical prostatectomy) to one of 3 doses of plain vitamin D: 400, 10,000 or 40,000 IU/day. They administered these doses for three to eight weeks before the surgery. Then, after the surgery, they measured the amount of activated vitamin D inside the prostate cancer, as well as two “markers” of cancer growth.
To everyone’s surprise (except perhaps Professor Vieth?), his group found that activated vitamin D levels inside the cancerous prostate increased significantly with each increasing dose of plain vitamin D. 40,000 IU/day resulted in the highest levels of activated vitamin D inside the prostate cancer. These higher levels of activated vitamin D inside the cancer were associated with significantly lower levels of a “bad” marker (Ki67, a protein that indicates prostate cancer cell growth) and higher levels of a “good” marker, one having to do with growth inhibition of the cancer.
This is an exciting discovery. It means that plain vitamin D may help slow the growth of some cancers. If you are scheduled for prostate cancer surgery, Professor Vieth does not advise you to take 40,000 IU of vitamin D/day for 2 months before the surgery. However, I can advise you to keep your vitamin D levels in the high range of normal (70-90 ng/ml), which will mean about 10,000 IU/day for most men.
Remember that in 2009, a Norwegian group found that “high” vitamin D levels at the time of diagnosis of prostate cancer were associated with remarkable reductions in subsequent death rates (RR=.09).
As the authors said, “To conclude, this study shows a strong association between 25(OH)D levels and mortality in patients with prostate cancer.” They classified “high” vitamin D levels as anyone above 32 ng/ml, levels easily achieved with 5,000 IU per day in just about everyone, regardless of their weight or genetics.