By Craig Weatherby
Apparent links between higher levels of vitamin D and reduced cancer risks have been accumulating since the 1940’s.
Indications are particularly strong for cancers of the digestive tract, including colon cancer, and certain forms of leukemia.
However, these associations have emerged from epidemiological studies, which cannot prove a cause-effect relationship.
(Our reports on some of these studies can be found in the Vitamin D & Immunity
section of our news archive.)
The credibility of these links is bolstered by studies in human cells and animals … which suggest some possible explanations for why vitamin D appears to curb the development and spread of cancers.
As researchers wrote earlier this year, “… vitamin D participates in cell growth regulation, apoptosis and cell differentiation. In addition, it has been implicated in the suppression of cancer cell invasion, angiogenesis and metastasis.” (Lopes N et al. 2012)
Vitamin D can be obtained from supplements, fatty seafood, and exposure to strong sunrays during the spring and summer months.
Sadly, sun avoidance and lack of fatty fish and/or supplements has made vitamin D deficiency or insufficiency common in North America and in many countries worldwide.
Fish fit the bill:
Sockeye stand out
In addition to getting vitamin D from supplements, certain fish rank among the very few substantial food sources of vitamin D, far outranking milk and other D-fortified foods.
Among fish, wild sockeye salmon rank as the richest source, with a single 3.5 ounce serving surpassing the US RDA of 600 IU by about 15 percent:
Vitamin D per 3.5 oz*
Sockeye salmon 687 IU
Albacore tuna 544 IU
Silver salmon 430 IU
King salmon 236 IU
Sardines 222 IU
Sablefish 169 IU
Halibut 162 IU
*Click here for our our full test results.
Now, researchers at Montreal’s McGill University have discovered another reason why vitamin D appears to exert cancer-preventive and cancer-curbing effects.
Cell study suggests a new anti-cancer power of vitamin D
A team led by McGill professors John White and David Goltzman discovered that vitamin D acts in several ways to inhibit the production and function of a key protein called cMYC (Salehi-Tabar R et al. 2012).
They just published their findings in the latest edition of the prestigious U.S. journal, Proceedings of the National Academy of Sciences.
The cMYC protein drives cell division and is active at high levels in more than half of all cancers. “For years, my lab has been dedicated to studying the molecular mechanisms of vitamin D in human cancer cells, particularly its role in stopping their proliferation,” said Prof. White.
“We discovered that vitamin D controls both the rate of production and the degradation of cMYC. More importantly, we found that vitamin D strongly stimulates the production of a natural antagonist of cMYC called MXD1, essentially shutting down cMYC function”. (MU 2012)
The team also applied vitamin D to the skin of mice and observed a drop in the level of cMYC and found evidence of a decrease in its function.
And mice that lacked the specific receptor for vitamin D had very high levels of cMYC in a number of tissues, including skin and the lining of the colon.
“Taken together, our results show that vitamin D puts the brakes on cMYC function, suggesting that it may slow the progression of cells from premalignant to malignant states and keep their proliferation in check”, said Dr. White (MU 2012).
He went on to make two key points: “We hope that our research will encourage people to maintain adequate vitamin D supplementation and will stimulate the development of large, well-controlled cancer chemo-prevention trials to test the effects of adequate supplementation.” (MU 2012)
Their study was funded by the Canadian Institutes of Health Research and the National Cancer Institute/Canadian Cancer Society Research Institute.
Lopes N, Paredes J, Costa JL, Ylstra B, Schmitt F. Vitamin D and the mammary gland: a review on its role in normal development and breast cancer. Breast Cancer Res. 2012 May 31;14(3):211.
McGill University (MU). Newly discovered effects of vitamin D on cancer: Vitamin D slows the progression of cells from premalignant to malignant states, keeping their proliferation in check November 22, 2012. Accessed at http://www.mcgill.ca/newsroom/channels/news/newly-discovered-effects-vitamin-d-cancer-219089
Patel JB, Patel KD, Patel SR, Shah FD, Shukla SN, Patel PS. Recent candidate molecular markers: vitamin D signaling and apoptosis specific regulator of p53 (ASPP) in breast cancer. Asian Pac J Cancer Prev. 2012;13(5):1727-35.
Salehi-Tabar R, Nguyen-Yamamoto L, Tavera-Mendoza LE, Quail T, Dimitrov V, An BS, Glass L, Goltzman D, White JH. Vitamin D receptor as a master regulator of the c-MYC/MXD1 network. Proc Natl Acad Sci U S A. 2012 Nov 13;109(46):18827-32. doi: 10.1073/pnas.1210037109. Epub 2012 Oct 29.