Cancer news about sunlight isn’t all bad
Stress for Success
March 4, 2008


Is the sun more friend or foe? 1960s researchers found both higher rates of cancer in regions with less sunlight and more melanoma where there’s greater sunshine. The “foe” research has dominated warning us ever since to slather on the sunblock. Recently, however, some are questioning the wisdom of too much sun avoidance.

Sunshine is definitely the biggest source of vitamin D, which builds strong bones. But vitamin D also helps regulate almost every physical system, leading some scientists to advise that some unprotected sun exposure can be vitally important in preventing autoimmune disorders, cardiovascular disease and even cancer, sending shockwaves through skin cancer professionals.

Consider some of the research:
§ If you live at high latitudes you're more likely to develop and die from cancers of the colon, pancreas, prostate, ovaries, and breast leading to the possibility that direct sunlight protects against cancer.
§ In 1980, mortality rates from colon cancer deaths in the United States were the highest for those with the least amount of natural light exposure - in big cities and in rural areas at high latitudes suggesting a link to vitamin D.

The evidence is so convincing that some scientists say the most effective way to protect against cancer, besides not smoking and moderating alcohol use, is to get enough vitamin D.

It’s also now known that most tissues and cells, including in the colon, breast, immune system, and the brain, have receptors for vitamin D. Beyond producing calcium, vitamin D stimulates the secretion of insulin, impacts the immune system, and helps to regulate how cells grow, mature, reproduce, differentiate and die. "There's good evidence that every cell and tissue in the body needs vitamin D for optimal function," says Michael Holick, world-renowned vitamin D expert and professor of medicine at Boston University.

§ Vitamin D suppresses autoimmune reactions, perhaps explaining why multiple sclerosis, a disease thought to cause immune cells to attack the body's own nerve cells, is 50% lower in people who live in latitudes below 35°.
§ Hypertension and cardiovascular disease are more prevalent at higher latitudes and among those with dark skin pigmentation, which limits skin manufacture of vitamin D.
§ In a 1998 Holick experiment, hypertensive patients were treated with ultraviolet light three times a week for nine weeks increasing their vitamin D levels by 180% and returning their blood pressure to normal.

Europeans researching vitamin D compared death rates of those receiving the vitamin with those taking a placebo. "The results were remarkable," says Edward Giovannucci of Harvard’s School of Public Health. "People taking supplements of 300-2000 IU of vitamin D had a statistically significant reduction in mortality from any cause." The study also revealed no downsides to these doses.

Others caution that this evidence only shows association, not cause and effect, just like with beta-carotene and vitamin E studies that promised cancer protection but failed when rigorously tested. Giovannucci counterpoints that there have been no randomized trials showing that using sunscreen reduces melanoma either; just observational data.

Whom to believe? Next week we’ll consider this further.

Jacquelyn Ferguson, M. S., of InterAction Associates, is a trainer and a Stress Coach. E-mail her at www.jackieferguson.com with your questions or for information about her workshops (like Slow Down You Move Too Fast at FGCU on March19) on this and other topics and to invite her to speak to your organization.