Nov 26, 2012 by MAE CHAN
Canadian Researchers Discover New Evidence That Vitamin D Shuts Down Cancer Cells
Researchers at McGill University have discovered a molecular basis for the cancer preventive effects of vitamin D, whereby its active form essentially shuts down cancer cells.
People with higher blood levels of vitamin D live significantly longer than people who have low blood levels of the vitamin.
The team, led by McGill professors John White and David Goltzman, of the Faculty of Medicine’s Department of Physiology, discovered that the active form of vitamin D acts by several mechanisms to inhibit both the production and function of the protein cMYC. cMYC drives cell division and is active at elevated levels in more than half of all cancers. Their results are published in the latest edition of Proceedings of the National Academy of Sciences.
For the past several years, there has been considerable interest in the role vitamin D plays in improving health and preventing disease. Previous finding show that low levels of vitamin D have been directly associated with various forms of cancer and cardiovascular disease. Stephen B. Kritchevsky, PhD, Professor of Internal Medicine and Transitional Science at the Wake Forest School of Medicine found a signficant correlation.
"We observed vitamin D insufficiency (defined as blood levels <20 ng/ml), in one third of our study participants. This was associated with nearly a 50 percent increase in the mortality rate in older adults," said Kritchevsky. "Our findings suggest that low levels of vitamin D may be a substantial public health concern for our nation's older adults."
Although vitamin D can be obtained from limited dietary sources and directly from exposure to the sun during the spring and summer months, the combination of poor dietary intake and sun avoidance has created vitamin D deficiency or insufficiency in large proportions of many populations worldwide. It is known that vitamin D has a wide range of physiological effects and that correlations exist between insufficient amounts of vitamin D and an increased incidence of a number of cancers. These correlations are particularly strong for cancers of the digestive tract, including colon cancer, and certain forms of leukemia.
“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”.
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. Moreover, other mice, which lacked the specific receptor for vitamin D, were found to have strongly elevated levels of cMYC in a number of tissues including skin and the lining of the colon. The finding suggests that topical vitamin D may be just as effective as ingested to prevent cancer.
Chemoprevention Through Vitamin D Without The Side Effects
“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. We hope that our research will encourage people to maintain adequate vitamin D supplementation and will stimulate the development of large, well-controlled cancer chemoprevention trials to test the effects of adequate supplementation,” said Dr. White.
It's been known that vitamin D can prevent that genetic damage. When vitamin D binds to specific receptors, it sets off a chain of events by which many toxic agents including cancer cells are rendered harmless. However, if there is not enough vitamin D the system can become overwhelmed and cancer can develop. "This is one of the reasons that people living closest to the equator have a much lower incidence (or absence) of specific cancers which consequently increase in locations further from the equator."
The link between vitamin D intake and protection from cancer dates from the 1940s when Frank Apperly demonstrated a link between latitude and deaths from cancer, and suggested that sunlight gave "a relative cancer immunity".
Both D3 and D2 precursors are hydroxylated in the liver and kidneys to form 25- hydroxyvitamin D (25(OH)D), the non-active 'storage' form, and 1,25-dihydroxyvitamin D (1,25(OH)2D), the biologically active form that is tightly controlled by the body.
There is growing evidence that 1,25(OH)2D has anticancer effects, but the discovery that non-kidney cells can also hydroxylate 25(OH)D had profound implications, implying that higher 25(OH)D levels could protect against cancer in the local sites.
Theories linking vitamin D deficiency to certain cancers have been tested and confirmed in more than 200 epidemiological studies, and understanding of its physiological basis stems from more than 2,500 laboratory studies, according to epidemiologist Cedric Garland, DrPH, professor of family and preventive medicine at the UC San Diego School of Medicine. "This is the number one chemopreventive substance on the planet and its natural without side effects."
Dr. Garland’s findings only lend further credence to the mountain of growing evidence that optimal levels of vitamin D are essential for your health. Here are just a few highlights into some of the most noteworthy findings:
* Some 600,000 cases of breast and colorectal cancers could be prevented each year if vitamin D levels among populations worldwide were increased, according to previous research by Dr. Garland and colleagues. And that’s just counting the death toll for two types of cancer.
* Optimizing your vitamin D levels could help you to prevent at least 16 different types of cancer including pancreatic, lung, ovarian, prostate, and skin cancers.
* A large-scale, randomized, placebo-controlled study on vitamin D and cancer showed that vitamin D can cut overall cancer risk by as much as 60 percent! This was such groundbreaking news that the Canadian Cancer Society has actually begun endorsing the vitamin as a cancer-prevention therapy.
* Light-skinned women who had high amounts of long-term sun exposure had half the risk of developing advanced breast cancer (cancer that spreads beyond your breast) as women with lower amounts of regular sun exposure, according to a study in the American Journal of Epidemiology.
* A study by Dr. William Grant, Ph.D., internationally recognized research scientist and vitamin D expert, found that about 30 percent of cancer deaths -- which amounts to 2 million worldwide and 200,000 in the United States -- could be prevented each year with higher levels of vitamin D.
Inflammation is likely at the root of many cases of vitamin D deficiency, and all chronic degenerative diseases.
Stay Away From Sunscreen
Skin color adapts to sunlight intensities which produce vitamin D or ultraviolet light damage to folic acid. Researchers at the University of Leeds suggest that people with very pale skin may be unable to spend enough time in the sun to make the amount of vitamin D the body needs -- while also avoiding sunburn. The key is to stay away from conventional subscreen and use non-toxic alternatives to extend exposure time.
The further you live from the equator, the longer exposure you need to the sun in order to generate vitamin D. Canada, the UK and most U.S. states are far from the equator and the logic of using sunscreen is quickly becoming illogical even in scientific circles.
Unlike fads that sizzled and fizzled, the evidence for Vitamin D's health benefits is now strong and keeps growing. If it bears out, it will challenge one of medicine's most fundamental beliefs: that people need to coat themselves with sunscreen whenever they're in the sun. Doing that may actually contribute to far more cancer deaths than it prevents, some researchers think.
The vitamin is D, nicknamed the "sunshine vitamin" because the skin makes it from ultraviolet rays. Sunscreen blocks its production, but dermatologists and health agencies have long preached that such lotions are needed to prevent skin cancer. Now some scientists are questioning that advice. The reason is that vitamin D increasingly seems important for preventing and even treating many types of cancer.
- Comprehensive scientific reviews indicate that 83% of 785 sunscreen products offer inadequate protection from the sun, or contain ingredients with significant safety concerns. Only 17% of the products on the market are both safe and effective, blocking both UVA and UVB radiation, remaining stable in sunlight, and containing few if any ingredients with significant known or suspected health hazards. The assessment is based on a review of nearly 400 scientific studies, industry models of sunscreen efficacy, and toxicity and regulatory information housed in nearly 60 government, academic, and industry databases.
- Many products lack UVA protection. Fully 12% of high SPF sunscreens (SPF of at least 30) protect only from sunburn (UVB radiation), and do not contain ingredients known to protect from UVA radiation, the sun rays linked to skin damage and aging, immune system problems, and potentially skin cancer. FDA does not require that sunscreens guard against UVA radiation.
- Sunscreens break down in the sun. Parodoxically, many sunscreen ingredients break down in the sun, in a matter of minutes or hours, and then let UV radiation through to the skin. Our analyses show that 54% of products on the market contain ingredients that may be unstable alone or in combination, raising questions about whether these products last as long as the label says. FDA has not proposed requirements for sunscreen stability.
Mae Chan holds degrees in both physiology and nutritional sciences. She is also blogger and and technology enthusiast with a passion for disseminating information about health.