Remember all the advice we’ve heard about skin cancer — stay out of the sun, cover up, wear sunblock?
Now some doctors are saying that it has resulted in a new health problem - millions of people worldwide are suffering from vitamin D deficiency. And the scientific and therapeutic disagreements between dermatologists and nutritionists are heating up.
Dr. Michael Holick, a Boston University professor of medicine and physiology and author of a forthcoming book “The Vitamin D Solution,” has called the deficiency “probably the most common nutritional and medical condition in the world,” affecting “more than 50 percent of the world’s population.”
Seventy-seven percent of Americans have insufficient amounts of vitamin D, according to a November article from Consumer Reports on Health, which cited a study published in the Archives of Internal Medicine that was based on government figures. Late last month, the journal Pediatrics published the first assessment of vitamin D levels in U.S. children ages 1 to 11, which said at least one-fifth don’t get enough vitamin D.
As research papers on the subject keep proliferating, more primary care doctors are recommending that patients take increased vitamin D doses through over-the-counter supplements.
The vitamin is actually an inert hormone produced photochemically in the skin of humans and most animals, a process stimulated by sunlight - and that’s where some of the rub is. Dermatologists have long maintained that exposure to the sun at peak hours without sunblock raises the risk of skin cancer, including deadly forms of melanoma.
“Dermatologists have gone way overboard in telling people to stay out of the sun,” Dr. Andrew Weil, a best-selling author, said in an interview. “A more useful view is that solar radiation can both increase and decrease cancer through a complex environmental interaction involving many variables, including differences in genes, biochemistry and lifestyle.”
Dr. Holick said his advice was to “be sensible,” though he lost his job as professor of dermatology at Boston University School of Medicine in 2004 as a result of his belief in the benefits of sunshine. “Fortunately, I had other appointments” elsewhere at the medical school, he said.
Dr. Marvin Lipman, chief medical adviser for Consumers Union, said he has no qualms about getting vitamin D by exposing his face and arms to the sun for 15 or 20 minutes midday with minimal or no sunblock. He had found his own levels low and, even though he is a “nonbeliever in supplements per se,” he recognizes that the vitamin “is one we don’t get enough of from food.”
Nor was he hesitant when, in talking about the differing views among professionals, he said in a half-joking way: “You can see a turf war coming up.”
But dermatologists say, vitamin D deficiency or not, that the cancer risks of sun exposure are certain and there’s no way to make a medical recommendation on “safe sun.”
“We know there is a known carcinogen in ultraviolet rays. So to say ’five minutes or such is safe’ - safer than what?” asked Dr. Sandra Read, a Washington dermatologist. “We are all so different in our skin types and composition, it would be hard to tailor a message that is safe.”
“What I tell my patients is that if you are deemed to be low [in vitamin D] by your doctor, you can do it safely by supplements and nutrients,” Dr. Read said.
Dr. Elizabeth Tanzi, a D.C. laser and cosmetic dermatologist who has a vitamin D deficiency herself, agreed that there are better and safer sources than the sun.
“What matters is where you are getting it,” she said. “You may be trading off something healthy with something that is a known risk. It is a slippery slope, a question of amounts, because no one can say exactly how much one needs.”
Dr. Holick’s work on the benefits of sunshine has come under attack in the past. Dr. Barbara Gilchrest, chairwoman of Boston University’s dermatology department, has called it “an embarrassment for this institution and an embarrassment for him.”
Though not referring specifically to Dr. Holick, Dr. Tanzi also said that “unfortunately, there is a lot of misinformation out there. It seems to pit physician against physician, and it shouldn’t.”
She acknowledged the studies showing vitamin D as aiding treatment of certain cancers, but also noted that very intense sun is linked to at least 65 percent of melanoma cases.
The American Academy of Dermatology issued a new position statement this summer acknowledging vitamin D deficiency as a widespread medical problem, though without changing its stance on sun exposure and the use of sunscreen.
“The Academy encourages those with concerns about their levels of vitamin D to discuss options for obtaining sufficient dietary or supplementary sources of vitamin D with their physician,” it says.
A study reported this year by the British Association of Dermatologists showed that 83 percent of Australian dermatologists during winter 2006 had only the minimum amounts of vitamin D needed for good health, lower than that of elderly inpatients in a Melbourne hospital.
Dr. Holick acknowledged that sunlight does increase the risk of the milder nonmelanoma forms of skin cancer, but he said that’s mainly because people falsely think using sunscreen will protect them and thus don’t limit or moderate their time in the sun.
As for deadly melanoma, he said there is not an inevitable relationship to spending time in the sun, provided one doesn’t regularly get sunburns.
“If you think about it, most melanomas occur on the least sun-exposed areas, and an occupation requiring sun exposure decreases the risk. It turns out when you put sunscreen on, you weren’t protected from [the sun’s ultraviolet radiation], which alters your immune system,” he said.
Dr. David Heber, professor of medicine and director of the University of California at Los Angeles’ Center for Human Nutrition, said that more complex factors may be at work in skin cancers and that dermatologists shouldn’t be so dogmatic.
“We don’t understand melanoma and its association with sun exposure,” he said.
Vitamin D’s main role is promoting the absorption of calcium and encouraging bone growth, the lack of which can cause a range of deformities and ailments. It also is essential for cell growth and an optimally functioning immune system.
A blood test can tell the level of vitamin D in a person’s body, but primary care doctors have not always requested patients be tested.
“We used to think it was just appropriate for bones and teeth, and now we hear about [its importance to] the brain, heart and muscles,” said Dr. Lipman, an endocrinologist.
Its lack “spans basically all chronic diseases,” Dr. Holick said in an interview. “Every tissue and cell on the body has a vitamin D receptor, which means every cell needs D to function. … It regulates bone health and increases the efficiency of the intestines to absorb the calcium that is critically important for nerve and muscle function. We now recognize most body tissues can activate vitamin D to regulate up to 2,000 genes.”
Just 700 to 1,000 IUs per day reduced falls in people older than 65, the British Medical Journal reported in early October. The IU is an international unit of measurement used for vitamins and other biologically active substances.
Women, who generally suffer bone loss after menopause, require special monitoring, but other conditions cause concern as well.
A report at an Oct. 8 symposium of the American Society of Clinical Oncology showed that 70 percent of women being treated for breast cancer at any age have low levels of vitamin D, subjecting them to decreased bone mass and greater risk of fractures.
The solution was to give them high doses of the vitamin - more than 7,000 IUs a day.
“The research is just exploding. It’s so different from what I was taught in medical school,” Dr. Weil said.
The vitamin “may reduce risk” of some of the most common and dangerous types of cancers by 50 percent or more, he states in his latest book, “Why Our Health Matters: A Vision of Medicine That Can Transform Our Future.”
Academic medicine doesn’t always agree on what is a proper supplement dose needed for optimum health.
But doctors do agree that while it’s possible to get enough vitamin D from diet, it’s rare and difficult. According to Dr. Holick, “that would require consuming more fortified milk, anchovies, sardines, wild salmon, egg yolks [and] cod liver oil than most people would find palatable.”
The standard in most multivitamin pills is only 400 IU. But many experts are recommending at least 800 IU per day, and Dr. Heber and Dr. Weil take 2,000 IU without fear. Dr. Weil said he does so with the biggest meal of the day, to help with absorption.
“The body deactivates excess, and there are just a few places in metabolism where this happens,” Dr. Heber said, explaining that a person would have to take more than 50,000 IU a day to worry about toxicity.
The vitamin’s boosters have traveled a zigzag path since the discovery in the 1930s of its connection to rickets, a bone-weakening disease that occurs at about age 6 in children who are deficient.
“That was a big issue all over the world, and it started to disappear when vitamin D was put into fortified milk,” Dr. Heber recalled. What happened next was that “population scientists looked at latitudes and saw that as you go towards the north pole and get away from the sun, you have more incidence of cancer of all kinds.”
Results of a clinical trial published in the New England Journal of Medicine showed the incidence of polyps - precursors of colon cancer - was much lower in people taking supplements of calcium and vitamin D.
Experts are divided on whether it matters when supplements are taken, but most agree that age and skin color are key considerations.
The older a person and the darker that person’s natural skin color is, the more difficult it is to make vitamin D in the skin. Sun exposure increases the number of vitamin D receptors in the skin but the number diminishes with age.
Today, people are indoors working or watching television or driving around in cars. When they are out in the sun, especially during peak hours - the period of 10 a.m. to 3 p.m., most useful for absorbing the vitamin’s benefits - they are advised by most physicians to wear sunblock.
“What Mother Nature did was design us to live outdoors. Back in the 1940s, 100 units prevented rickets, but now not even fortified milk does the job, and the incidence of rickets - even in the United States - is on the rise, especially among breast-fed infants,” Dr. Holick said.
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