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Is sunshine a safe source of vitamin?

September 27, 2009 12:36 am

LIVING IN America today and worrying about vitamin D overdose is like dying of thirst in the desert while worrying about drowning.

This is how one article expresses the changing ideas about vitamin D--ideas that are being radically revised thanks to researchers such as Dr. Michael F. Holick, professor of medicine, physiology and biophysics at Boston University Medical Center.

Somewhat infamous and something of a maverick, Holick claims we are in the midst of an "unrecognized epidemic" of vitamin D deficiency, which is "a disease of neglect."

This deficiency causes not just the classic bone mineralization diseases such as rickets, osteomalacia and osteoporosis, but apparently also hypertension, heart disease, vascular disease, multiple sclerosis, cognitive impairment, diabetes, arthritis and a variety of different cancers.

THE EARLY EPIDEMIC

It was in the Industrial Revolution--when the population moved to dingy cities and away from sunlight--that children were found to be developing weak bones, bowed legs and growth delays from rickets.

Vitamins had just been discovered, and it was realized that this was a deficiency illness that could be corrected with cod liver oil, which contains lots of vitamin D. (Fatty fish and cod liver oil are used for treatment to this day.)

Then it was found that our skin is able to synthesize vitamin D, so exposure to sunlight could help prevent deficiencies.

But use of sunscreens, pigmentation of the skin, obesity and living in northern climes severely restrict this ability. And in winter--especially in the northern states (north of Atlanta, approximately)--the sun is not strong enough to produce vitamin D.

So we tend to be deficient by the end of winter.

THE CONTROVERSY

While there is growing consensus that vitamin D deficiency has become increasingly common, there's debate when it comes to how to treat and prevent it.

Part of what has made Holick somewhat controversial is his recommendation that we deliberately expose ourselves to UV light--either sunlight or with tanning beds. He also questions the wisdom of slathering ourselves with sunscreen.

"You'd wind up on 'America's Most Wanted' list for child abuse if you put your child outside without sunscreen," he quips.

The dogma preached to us by the dermatologists, of course, is to avoid the sun like the plague because of the alarming rise in the prevalence of skin cancers.

Holick, though, notes that most melanomas occur in areas not exposed to the skin. And in his book "The UV Advantage," he advocates sensible sun exposure and use of tanning beds--though this was an embarrassment to his department at Boston University, and he was stripped of the nominal title he also held of "professor of dermatology."

Holick published a review of his research--that showed we need more vitamin D than previously thought, and it's OK to get it from tanning--in the New England Journal of Medicine in 2007. But that enhanced his reputation as a maverick, and got him into even hotter water with the dermatologists when it turned out he received $150,000 worth of funding from the Indoor Tanning Association.

The battle is quite rancorous, with organizations such as the Skin Cancer Foundation--which touts itself as "the leading skin cancer prevention organization"--telling us to wear sunscreen all the time and never tan.

It is not just maverick Holick, however, who is advocating the need for adequate vitamin D levels and claiming the great advantage of adequate vitamin D.

Dr. Edward Giovannucci, a professor of medicine and nutrition at Harvard--speaking at an American Association of Cancer Research meeting in California--noted the remarkable anti-cancer effects of vitamin D, even in protecting against skin cancer. His research suggests that vitamin D might help prevent 30 deaths for each one from skin cancer.

THE DEFICIENCY EPIDEMIC

The debate is sure to continue, as multiple studies have found people deficient in vitamin D. It is "epidemic" in adults over age 50, notes Holick. And "most blacks in the United States are vitamin D deficient," he claims.

Part of what has put people in the deficiency category is the change in what is considered a normal blood level.

Now, it is recommended that levels should probably be in the 30- to 50-ng/mL range--which makes for optimal calcium absorption and bone health--whereas previously, levels of 15 were considered acceptable.

Deficiency appears to be responsible for an ever-growing list of maladies, including bone pain, fatigue and muscle weakness, that are often misdiagnosed as depression or chronic fatigue syndrome.

There also seems to be a correlation with colorectal, breast and prostate cancer, and residents of New England are more likely to die of cancer than those of southern states such as Georgia and Alabama.

Vitamin D also seems to regulate the chemistry of the immune system; it is postulated that we have outbreaks of flu in the winter because at that time, our levels are low.

Ideas about toxicity are changing, also. The previous upper limit of what was thought to be a safe intake (2,000 IU in adults) has now been revised upward to 10,000 IU.

Vitamin D is a hot topic. The latest thinking is that it is not just a vitamin, but also a hormone--which many of us are deficient in and which is associated with an ever-growing list of maladies.

Holick's claim is that we have been too timorous in our supplementation, which should include judicious use of ultraviolet light/sunlight.

Like so many things in medicine, the pendulum swings one way, then back the other. My personal bias is that some UV light/sun is not so harmful--and its ill effects may have been over-emphasized. But I may not be invited to many dermatology cocktail parties if I take that line.

Dr. Patrick Neustatter is a family practitioner in North Stafford. Dr. Patrick Neustatter can be reached at
Email: newsroom@freelancestar.com.