Vitamin D Newsletter


Sunlight Reduces Cancer

Shannon from Massachusetts writes:

Dr. Cannell: My mother died of breast cancer and my sister has had it for two years. Now I have it. How much vitamin D should I take?

Dr. Cannell replies:

As I've said before, if I had cancer, I'd take at least 10,000 IU  of vitamin D every day in the colder months. In the warmer months, I'd stop the vitamin D and get a safe amount of noontime sunshine. I'd keep my 25-hydroxy vitamin D levels between 50–80 ng/mL, year around. However, I do that now and I've not been diagnosed with cancer. Several recent studies are relevant to breast cancer. Dr. Carlo Palmieri, and his group from the Imperial College in London, found that women with early stage breast cancer had higher vitamin D blood levels than women with more advanced cancers. 

Even more important was the third study reported to date, this time by Dr. Lim at the King's College in London, showing improved survival when cancer is diagnosed in sunnier months. Studies of season of diagnosis and cancer survival are very important because they imply a treatment effect from higher vitamin D blood levels.

In terms of sunlight and cancer incidence, a recent literature review found 94 studies. The authors threw out 67 of the papers for not meeting their strict criteria, although every one of the discarded papers looking at the big three (prostate cancer, breast cancer, and colon cancer) showed sunlight reduces cancer. Of the remaining 27 papers, 8 of 8 prostate cancer papers, 7 of 7 breast cancer papers, and 5 of 6 colon cancer papers showed sunlight prevented cancer. The authors concluded, "There is increasing and conclusive evidence that sunlight has a preventative effect on the initiation and/or progression of prostate and breast cancer, colon and possibly also ovarian cancer." Someone needs to tell that to Professor Gilchrest.

All this leaves us with a question, "Are physicians responsible for their advice?" When dermatologists or other physicians subvert the vitamin D steroid hormone system by telling patients to avoid the sun, do they assume an affirmative duty to assess and maintain the vitamin D system they have subverted? Do they have a duty to inform their patients about relevant risks of sun-avoidance? Do they have a duty to inform their patients about relevant risks of vitamin D deficiency? How many dermatologists even bother to check vitamin D levels in their pale-as-ghost patients? How many bother to advise vitamin D supplements? If they do advise supplements, how many advise enough vitamin D to compensate for lack of sunlight? These are questions for tort lawyers.

Page last edited: 16 August 2010