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Is Vitamin D the Wonder Drug of the 21st Century?

Armen Hareyan's picture

Reading the buzz in the press these days, one might think Vitamin D has a major role to play.

A few months ago, I posted a story about vitamin D and breast cancer. It was a post discussing a report presented at this year’s meeting of the American Society of Clinical Oncology that showed that although vitamin D may not prevent the development of breast cancer, there seems to be a correlation between vitamin D levels and distant disease-free survival (the percentage of women alive with no evidence of spread of their disease) in women who develop the disease.

This prompted some interesting discussion in the comments, with one reader talking about taking vitamin D supplements and another expressing concern that people would start taking supplements without understanding potential consequences. Yet another reader, Ryan W., raised the question about whether vitamin D levels alone exert the observed effects, or whether what is really being seen is an interaction between vitamin D and infection/inflammation as discussed in this blog post. These are great points and questions – so I thought I would address some of them.

First of all, vitamin D metabolism is very complicated.

This graphic, borrowed from an excellent website by the University of Washington, shows how vitamin D is made from cholesterol in the liver and activated by sunlight in the skin and then further activated by the liver and kidneys to make the active form, 1, 25 (OH)2 vitamin D. This active form binds to a protein found inside vitamin D-responsive cells called the Vitamin D Receptor. The complex between 1, 25 (OH)2-vitamin D and its receptor then enters the nucleus and changes the activity level of dozens (if not hundreds) of genes. Most of the so-called vitamin D target genes have not yet been identified, so the specific mechanism by which vitamin D does anything, from regulating calcium metabolism to influencing the immune system is not known.

Regardless of how it happens, more and more research is demonstrating beneficial effects of vitamin D in patients with colorectal carcinoma. Just last year, a study was published showing a correlation between vitamin D levels and the risk of developing colorectal carcinoma. This was a type of study called a meta-analysis, which combines the results of several smaller studies to strengthen the statistical support for the conclusion. In this particular report, the results of 5 previously published studies on the correlation between vitamin D and the development of colorectal carcinoma were analyzed together.

Figure 2 of that report, reproduced here, shows that when data from all 5 previous reports are combined, they show a significant (almost 50%) drop in the rate of colorectal carcinoma in the patients with the highest blood vitamin D levels compared to the patients with the lowest levels.

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This does not mean that taking vitamin D supplements can necessarily decrease your risk of getting cancer. It only shows that people who have higher vitamin D levels are less likely to get this particular type of cancer. It shows a correlation, but the cause could be from something else entirely. However, another study published last year suggests that the effect may really derive from vitamin D itself. In this study, 1180 white women older than 55 and in otherwise good health were randomly assigned to one of three groups: 1) placebo, 2) calcium supplementation with a vitamin D placebo, or 3) supplementation with both calcium and vitamin D.

Figure 2 from their paper shows the fraction of women without cancer among the three groups. The group that took both vitamin D and calcium supplementation developed cancer at a lower rate than either of the other two groups.

Just last month, another paper in the Journal of Clinical Oncology was published showing a beneficial relationship between vitamin D and survival from colorectal cancer. In this case, the investigators examined the correlation between prediagnosis vitamin D levels and survival among 304 participants in the Nurses’ Health Study and the Health Professionals Follow-Up Study who were diagnosed with colorectal cancer from 1991 to 2002. They found that higher vitamin D levels in the blood were correlated with improved overall survival.

So does this mean that we should all start taking vitamin D supplements? I don’t think so. First of all, it remains unclear how vitamin D impacts on the development of cancer and on the survival of cancer patients. Other than the study of white women from Nebraska, none of the reports is an “intervention study.” This means that one factor (vitamin D level) was compared with another (survival). A study like this can’t possibly prove that the one causes the other. Maybe the people with high vitamin D levels have better overall eating habits or exercise more in the sun, or have genetic difference in the way that their body metabolizes vitamin D. Any of these might also influence survival and would NOT be duplicated by taking a supplement.

How about the supplement study? The major limitation there is that subjects were all post-menopausal white women from Nebraska. Whether supplementation will help any other population is not clear at all.

Also, as with all other facets of nutrition, too much of a good thing can be a bad thing.

Too much vitamin D can hurt peripheral arteries, causing calcium deposition and inflammation and decreasing their elasticity. Excess vitamin D, if it results in excess serum calcium, can also contribute to the development of kidney stones. So, please, before taking any supplement, please check with your health care provider to determine if this is right for you and your specific medical history.

Regardless of whether or not supplementation is warranted, recent studies do all point to the same thing: vitamin D probably has effects on your body far beyond bone health. Future work will hopefully clarify how vitamin D affects the development of cancer and survival once cancer is diagnosed.



I am a survivor of the vitamin D holocaust! I know that these are strong words but considering the recover that I had I believe that vitamin D is a miracle drug. I like the way that Oliver Gillie says it in his Sunshine Robbery that is it is not a magic bullet but a magic shotgun in how it affects so many systems in the body. The fear of the sun in the last forty years has driven us away from health into an array of chronic disease. This paradigm change will take some time but is well worth it. I would most likely be in a wheel chair or dead if I had not found vitamin D as it has healed my degenerative disc disease as well as my heart. I have been taking it for 3-1/2 years now and my health continues to improve. I used holocaust because Dr. William Grant describes 257,000 less cancer deaths in the US in 2007 if everyone only got 2000 IU per day which is an amount described as safe by current standards. Imagine a similar result in other chronic disease. If everyone took enough to become replete our health care problems would be solved except what to do with the extra health care professionals and health insurance professionals.
This is only about supplements. Why not get your Vitamin D now through MODERATE/RESPONSIBLE UV light? I've been doing this for going on 6 years for a total of 15 minutes a week in a tanning bed. If you get your Vitamin D naturally your body know when to stop producing it. As far as skin cancer don' t get burned and keep your dermatoligist happy by visiting him and dropping him off some money often.
The active version, 1, 25 (OH)2, of vitamin d is closely regulated by the body. It does not vary significantly with vitamin d intake/ creation from sun light. High levels of the active version are only seen with a few diseases eg some lymphomas, where the lymphoma creates the active vitamin d by-passing the regulating mechanism. Increasing the level of active vitamin d is not a good idea, although it is used to treat some medical conditions. It is the so called inactive version, 25 (OH)2, that appears to be important to health and the body makes vast amounts of this given half a chance, the problem these days is we don't give it half a chance, as we tend not to go out at midday. I would also argue that vitamin d3 (the supplement or what is produced in the skin) is a food not a drug. It seems, to me, we worry about drowning while we die of thirst, as publications often report 30-40% of people in the research having inadequate levels of vitamin d ( 25 (OH)2,) although they have normal levels of 1, 25 (OH)2.
Citus fruit (oranges limes etc) was found to ward off scurvy in the 17th century. It was unclear at the time how citrus fruit impacted on the development of scurvy, bit it seemed to work. Does that mean people should have eated citrus fruit? Of course, no need to wait 200 years or more to work out how citrus fruit saved lives was it?
I agree with the previous commenter. The tide is turning for the public's awareness and attitude about the importance of sunshine and vitamin D. We should be asking who are the responsible parties for this situation and hold them responsible. http://www.vitamindcouncil.org/newsletter/2007-nov.shtml