Vitamin D and Cancer

From the September 2005 edition of Dr. Fuhrman's Healthy Times:

Laboratory, animal, and epidemiologic evidence suggests that vitamin D may be protective against cancer. Epidemiologic studies suggest that a higher dietary intake of calcium and vitamin D, and/or sunlight-induced vitamin D synthesis, correlates with lower incidence of cancer, including lymphoma, breast, prostate, and colon cancer.1 In fact, for over 60 years, researchers have observed an inverse association between sun exposure and cancer mortality,2 and those with more sun exposure had fewer cancers. The inverse relationship between higher vitamin D levels in blood and lower cancer risk in humans shows a significantly lower risk among those with the highest vitamin D intake.

In addition to its significant cancer-protective effects, recent studies demonstrate that vitamin D also can inhibit the growth of existing breast and prostate cancer cells. Likewise, it helps inhibit the progression and metastasis of a wide spectrum of cancers, suggesting therapeutic value in the treatment of those who already have cancer.3

Interestingly, one dermatologist, Dr. Michael Holick, even wrote a book, The UV Advantage, advocating a moderate dose of sunlight. He was promptly kicked off the faculty of the Boston University School of Dermatology. Dr. Boni E. Elewski, president of the American Academy of Dermatology, maintained that even a few minutes of sun can be dangerous and promote skin cancer. Dr. Holick’s critics pointed out that the Indoor Tanning Association contributed $150,000 to his research.

In Dr. Holick’s defense, we must consider the keynote address that was presented at the meeting of the American Association for Cancer Research, where Dr. Edward Giovannucci, professor of medicine and nutrition at Harvard, said that his research suggests that deaths from cancer in cases where vitamin D would have been of benefit outnumber skin cancer deaths 30 to one. “I would challenge anyone to find a nutrient or any factor that has such considerable anti-cancer benefits as vitamin D,” he said.

Avoiding sun damage or not should not be the point here, because even a little bit of sun, as
Dr. Holick suggests, is not really necessarily going to guarantee you an ideal blood level of vitamin D. Most of us simply need to supplement with an appropriate dose of vitamin D. The RDA of 400 IU may be an appropriate dose to obtain a normal blood level in many people, but there is still a significant portion of people who need more. To be safe, you should take more vitamin D or measure the vitamin D level in the blood to assure you are taking enough. While common sense might lead you to think that the vitamin D your body produces from sunshine is superior to the vitamin D from supplements, the documented beneficial effects of both sources are the same, and with supplements you don’t risk damaging your skin.

For more on vitamin D, check out these previous posts:
1. Martinez ME, Willett WC. Calcium, vitamin D, and colorectal cancer: a review of the epidemiologic evidence. Cancer Epidemiol Biomark Prev 1998;7:163-68. Lieberman DA, Prindiville S, Weiss DG, Willett W. Risk factors for advanced colonic neoplasia and hyperplastic polyps in asymptomatic individuals. J Am Med Assoc 2003; 290:2959-67.

2. Heaney RP. Long-latency deficiency disease: insights from calcium and vitamin D. Am J Clin Nutr 2003;78:912-9.

3. O’Kelly J, Koeffer HP. Vitamin D analogs and breast cancer. Recent Results Cancer Res 2003;164:333-48. Giovannucci E. The epidemiology of vitamin D and cancer incidence and mortality: a review. Cancer Causes Control 2005; 16(2):83-95.
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Edward Hutchinson - March 15, 2007 5:54 AM

There is an informative, easy to follow, graphical representation of the way Vitamin D is made in the skin here http://www.uvguide.co.uk/vitdpathway.htm. It may help people understand why staying out in the sunshine for too long is counterproductive.
As Vitamin d synthesis is complete in a quarter of the time it takes to burn, those who get even the slighest burnt have been out in the sun for far too long.
The benefits of regular LIMITED sun exposure though do need to be stressed.
Perhaps readers would find The Antibiotic Vitamin http://www.sciencenews.org/articles/20061111/bob9.asp interesting particularly the references. Since that article was published there has been more to support it.
The vitamin D system in skin may also be part of an intrinsic protective mechanism against UV damage.
http://www.ncbi.nlm.nih.gov/entrez/query.fcgi?db=pubmed&cmd=Retrieve&dopt=AbstractPlus&list_uids=17170736

will - November 25, 2007 4:45 AM

what is the problem/diseases do you get if not enough vitamin d is intaken

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