Huffington Post Health Watch: Vitamin D and Breast Cancer
Click on the Living Section of the Huffington Post today (August 24, 2009) and you'll see large photo of a woman rubbing her breasts.
The large lavander-colored headline above it "Protect Your Breasts With Vitamin D"
The post is written by Dr. Christiane Northrup, who I've mentioned both in my Salon pieces on Oprah Winfrey and Arianna Huffington. In it, Northrup dives into the opinion that Vitamin D prevents breast cancer.
"Exciting new research shows that in the U.S. alone, thousands of new cases of breast cancer could be prevented every year if more women had optimal levels of vitamin D." she writes. Then Northrup cites her proof:
"A study conducted by Cedric Garland and other prominent vitamin D researchers determined that women with vitamin D levels above 52 ng/ml have half the risk of developing breast cancer as those with 13 ng/ml! Garland (et al) estimates that 58,000 new cases of breast cancer in the U.S. could be prevented per year by raising vitamin D levels to 52 ng/ml. Imagine what the global impact could be!"
Later, she concludes: "This is preventive medicine at its finest."
That's a bold statement. In wanting to continue to follow the story about the Post's dubious health advice, I took a closer look at Dr. Northrup's claim. To do that, I had to dig into the medical literature first, since Dr. Northrup, true to HuffPo tradition, didn't add a link to the study she referenced.
I searched for studies under Dr. Garland's authorship between 1950 to August 2009. I found the study from April of 2006 Journal of Steroid Chemistry and Molecular Biology that seems to contain the information Dr. Northrup is referring to (I've linked to the abstract here. If you want to read the paper, you unfortunately need to pay for access).
The study does conclude that indeed, Vitamin D can prevent cancer. But there are a couple of important caveats:
- the data comes from observational studies--in plain English, an observational study is one where the researchers just watch their subjects. That's in contrast to a controlled study, where researchers divide subjects into groups and collect data based on what they assign those groups to take or do. In general, controlled studies are higher quality ones than observational studies.
- Second, the amount of Vitamin D the paper suggests is twice the recommended amount --- 4000 International Units (IU) versus 2000 IU. While you may think too much of a vitamin really isn't bad for you, in the case of Vitamin D (and several others, like Vitamin A), there is the potential to overdose. Among other things, Hypervitaminosis D can lead to bone and kidney problems.
What Dr. Northrup fails to mention is that since 2006, studies looking into the vitamin D-breast cancer link have , in many cases, failed to find an association.
Perhaps the most convincing evidence of that came out late last year, when researchers conducted a more stringent study in over 36,000 postmenopausal women. This was a prospective, randomized-controlled trial in which they gave one group of women vitamin D and the other placebo over 7 years. The result was that "invasive breast cancer incidence was similar in the two groups (528 supplement vs 546 placebo...." (by the way, that link is to the entire study because it's a journal published by the National Cancer Institute, funded by our tax dollars).
In fairness, this subjects in this study took only 400 IU of Vitamin D,and the authors noted that other observational studies have suggested (albeit very, very weakly), that doses over 400 IU can protect women from breast cancer.
On the other hand, women aren't trading one serious health problem (cancer) for another (vitamin D toxicity) by taking megadoses of a vitamin that isn't strongly proven to do anything.
One final point: at the end of her blog post Dr. Northrup recommends that women visit a tanning salon that offers UVB rays to accumulate vitamin D under the skin (sunlight is the main catalyst your body uses to generate vitamin D on its own).
A tanning salon? Really? What about the risk of tanning booths and skin cancer?
http://www.cancer.gov/newscenter/tip-sheet-tanning-booths
http://www.skincancer.org/the-case-against-indoor-tanning.html
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My advice, stay away from that Huffington Place.
Who is to know?
However, researchers point out that "Vitamin D discovery outpaces FDA decision making." They point out that "vitamin D not only regulates the expression of genes associated with calcium homeostasis, but also genes associated with cancers, autoimmune disease, and infection."
From the May 2007 issue of Life Extension Magazine:
"Vitamin D Guards Against Breast, Colorectal Cancers
Two newly published meta-analyses conclude that higher blood levels of vitamin D could prevent up to two thirds of colorectal cancers cases and up to half of breast cancer cases in the US.*
The colorectal cancer meta-analysis reviewed data from five studies in which blood collected from 1,448 healthy participants was tested for vitamin D and subjects were followed for up to 25 years. The researchers reported that raising serum levels of 25-hydroxyvitamin D to 115 nmol/L, corresponding to a daily intake of 2000 IU of vitamin D3, would reduce the incidence of colorectal cancer by two thirds.
The breast cancer meta-analysis included data from studies involving 1,760 women whose vitamin D levels ranged from less than 33 to 130 nmol/L.
women with the lowest blood levels had the highest rates of breast cancer, which dropped as blood levels of 25-hydroxy-vitamin D increased. The researchers concluded that the serum level associated with a 50% reduction in risk could be maintained by taking 2000 IU of vitamin D3 daily."
*Available at: http://health.ucsd.edu/news/2007/2_07_Garland.htm. Accesssed February 12, 2007.
From the Sept. 2008 Life Extension:
"Vitamin D Prolongs Breast Cancer Survival
Breast cancer patients with inadequate vitamin D blood levels may have poorer survival and prognosis than those with adequate levels of the "sunshine vitamin."*
In a study presented at a recent meeting of the American Society of Clinical Oncology, scientists from the University of Toronto measured vitamin D blood levels in 512 women with an averrage age of 50 years who had been newly diagnosed with breast cancer and tracked their progress for a median of 12 years.
...The study authors noted this is "the first time that vitamin D has been linked to breast cancer progresion." They added that "vitamin D deficiency is common at breast cancer diagnosis" and emphasized blood tests to ensure adequate levels of the vitamin, especially in women with breast cancer."
*Available at http://www.asco.org/ASCO/Abstracts+%26+Virtual+Meeting/Abstracts?vmview=abst_detail_view&conflD=55&abstractlD=31397. Accessed June 12, 2008.
Given the plethora of studies indicating the positive health benefits of higher serum levels of vitamin D in the blood, it is irresponsible to not point out the myriad benefits of supplementing your diet with vitamin D.
Vit D toxicity is nothing to sneeze at. Are they indifferent or just stupid?
http://tiny.cc/tSazW
thanks for your links--I haven't looked at all of them, but a couple of things
1) they are all magazine articles before the 2008 study I'm referring to that seems to discredit the notion of Vit D and breast cancer (I am not speaking to vitamin D and other kinds of cancers)
2) we may observe that women with breast cancer are deficient in Vitamin D, that doesn' t necessarily mean that Vitamin D could have prevented their cancer. It's an observation, but not causation.
That being said, I think Dr. Northrup's enthusiasm for vitamin D is based on relatively old research that now, may not prove to be true. In addtion, it bothers me that she one, suggests excessive vitamin D given that this prescription has risks and two, she suggests tanning salons. I've never seen a doctor suggest that given the risks.
2) Observation of years of meta-analysis reviewed data that raising the serum levels of Vit D is beneficial as a preventative, for improving prognosis and survival rates.
3) My point is that there are studies that show the benefits to higher serum levels of vit D. I made no mention of Dr. Northrup. The study you cite from last year (as you point out) only used 400 IU of vit D, not the recommended therapeutic 2000 IU that reduces by 50% the risk of breast cancer.
In both Europe and the U.S. tanning salons are regulated and the amount of UVB is limited. They are primarily UVA which does not have the redeeming quality of fostering vitamin D production.
I do think that sunlight is very important. We now know about vitamin D but sunlight also initiates the synthesis of other chemicals which may also be important to human health. I would like to see indoor lighting that mimics sunlight.
right--on the third point about dosing of Vitamin D--if you read the comments in the paper (by the way, I was told the link was broken, but I've fixed it), then you'll see that the data at that time showed a very weak association between doses of Vit D >400 IU and breast cancer.
Observational studies are helpful but they can't really answer whether something is true or not. The RCT that the folks at UCLA conducted is a much higher quality study. That being said, I am also aware that other controlled studies are underway.
amen to that! as a pediatrician, we're really pushing vitamin D for our patients.
http://www.huffingtonpost.com/dr-frank-lipman/vitamin-d-what-you-need-t_b_308973.html?utm_source=Goop+Newsletter&utm_campaign=cbcfd4a346-Goop55_11_05_2009&utm_medium=email
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