Experts clash over sun exposure to boost vitamin D

May 19, 2004

May 19, 2004

Boston, MA - An advocate of moderate exposure to the sun to satisfy the body's requirement for vitamin D has clashed with dermatologists who say it is imperative that people protect themselves from ultraviolet (UV) radiation [ 1 ].

"As a dermatologist who treats the ravages of skin cancer on a daily basis, it is appalling to me that anyone in good conscience could make the claim that intentional sun exposure—for any length of time—is beneficial," says Dr Darrel Rigel (New York University Medical Center, NY).

But that is exactly what Dr Michael Holick (Boston University School of Medicine, MA) is doing in his new book, The UV Advantage. Aimed at the general public and on sale as of this month, the book has already created a storm of controversy and has also led to a call for his resignation. In the book, Holick claims that moderate exposure to the sun has powerful health benefits and that current advice to avoid the sun has led to an epidemic of vitamin-D deficiency.

"Many who practice dermatology and their supporters in the sunscreen industry have scared the public right out of the sun, the best way to produce the vitamin D that the body needs," Holick maintains. "These naysayers have ignored the mountain of peer-reviewed science that demonstrates that moderate exposure to natural or artificial sunlight has a powerful, beneficial impact on health."

"There are important medical consequences of this continuing rhetorical campaign of fear and exaggerated claims," Holick maintains. "There is no doubt vitamin D is the best way for the body to control abnormal cell growth," he says, stating that sun exposure could lead to:

  • Improved bone health and prevention of osteoporosis, osteomalacia, and rickets.

  • Reduced risk of heart disease, stroke, and breast, colon, and other cancers.

  • Alleviation of skin disorders.

  • Decreased risk of autoimmune disorders, including multiple sclerosis, type 1 diabetes mellitus, and rheumatoid arthritis.

  • Enhanced mental health and lessening symptoms of seasonal affective disorder, premenstrual syndrome, and depression.

Some experts agree. Dr Robert Heaney (Creighton University, Omaha, NE) says: "Holick provides a much-needed antidote to the scare tactics of the skin mafia." Dr John Adams (University of California, Los Angeles and Cedars-Sinai Medical Center) says that the book Holick has written "provides the clinical community with the first balanced, unbiased view of the benefits and dangers of sunlight exposure in the last 50 years." Dr Jim Leyden (University of Pennsylvania, Philadelphia) has known Holick for 25 years and describes him as "an incredibly creative person who's made some really fundamental observations and discoveries in several areas," adding, "He's ahead of his time."

Dermatologists are furious

But dermatologists are furious, as his views are in direct contrast to their firm advice on UV protection. In a recent press release, the American Academy of Dermatology (AAD) said that the reports of health benefits of vitamin D from unprotected sun exposure are "unsubstantiated" and are causing further confusion among the public. "For decades, dermatologists have advised the public to practice proper sun protection to prevent skin cancer—and that same advice holds true today, despite any claims to the contrary."

The AAD advises everyone to practice a "comprehensive sun protection program, including avoiding outdoor activities between 10 am and 4 pm when the sun's rays are strongest, seeking shade wherever possible, wearing a broad-spectrum sunscreen with a sun-protection factor (SPF) of at least 15 and reapplying it every 2 hours, and wearing sun-protective clothing."

Separately, 2 medical institutions, the Mayo Clinic and the University of Alabama at Birmingham, have recently issued press releases emphasizing the need for sunscreen to reduce the risk of skin cancer. "Slather on the sunscreen. . . . Remember this when enjoying summer outdoor activities: there's no such thing as a safe tan," warns the May issue of the Mayo Clinic Health Letter.

Holick was even asked to resign from the dermatology department of Boston University earlier this year, when the contents of the book were first revealed. Although he hadn't trained as a dermatologist, Holick had been asked to join the department because so much of his research focused on skin conditions. But he was asked to leave in February by department chair Dr Barbara Gilchrest, an authority on melanoma. In an interview with the Boston Globe, she said that the book is "an embarrassment for this institution and an embarrassment for him," and added, "I read better things in ladies' magazines."

Gilchrest criticized his conclusions and suggested that his ties to the tanning industry may have influenced his research. (The Indoor Tanning Association is donating $150 000 for research over the next 3 years and has hired a publicist to promote the book.)

The resignation is largely symbolic, the newspaper reported, as Holick remains the director of the Bone Health Clinic at Boston University Medical Center and is continuing to teach with no loss in salary. He commented at the time that he was "being punished for challenging one of the dogmas of dermatology" and contends that public-health officials have been so insistent on painting sunshine as the enemy that they can't stand to hear about the substantial benefits of sunlight, including promoting strong bones and easing depression.

"It's easier for them to say just don't be exposed to sunlight instead of providing the thoughtful, intelligent recommendation that maybe a little sun is good for you," says Holick.

"I am not advocating a return to the baby-oil and sun-reflector tanning days of the past," he points out. "This is about spending a few minutes in natural or artificial sunlight several times a week—without sunscreen—to satisfy your body's vitamin requirement. It is not about damaging the skin."

AAD adamant about avoiding the sun

The AAD says Holick is "irresponsible" and likens his advice on going unprotected into the sun for health benefits to suggesting "smoking to combat anxiety." The academy emphasizes the risk of skin damage and skin cancer, reiterating its message at a recent news briefing to launch its Melanoma/Skin Cancer Detection and Prevention Month.

Speaking at the event, dermatologist Rigel pointed out that the US Department of Health and Human Services has declared UV radiation as a known carcinogen. One American dies every hour from melanoma, the most serious form of skin cancer, he points out. "The fact is, skin cancer is increasing at an alarming rate, and scientific research confirms that our best defense is avoiding excessive, unprotected sun exposure."

"Until there is science that tells us otherwise, it is imperative that people protect themselves from the sun. Anyone concerned about not getting enough vitamin D should either take a multivitamin or drink a few glasses of vitamin-D-fortified milk every day," he commented. "Normal vitamin-D levels are easily maintained through routine daily activities (even when wearing sunscreen) and a normal diet," he maintains, "so supplemental vitamin-D tablets are typically not needed."

Holick strongly disagrees. "It is improper for unenlightened dermatologists, many of whom know little about human nutrition, to suggest that consumers can get all their vitamin D from diet. It would require drinking 10 glasses of milk or fortified orange juice every day."

"The literature is clear. Adequate amounts of vitamin D cannot be achieved at the current low levels set years ago by the Institute of Medicine—200 IU a day," Holick says. "Consumers should routinely be taking 5 times that amount, 1000 IU a day of vitamin D. It is misleading to suggest that nutritional supplementation is the answer. It is not practical to get our daily 1000 IU of vitamin D from popping a pill. More important, supplements do not provide the same benefits as sunshine, and if taken in too large a dose, they can cause vitamin-D toxicity."

Epidemic of vitamin-D deficiency

"Today we face what is, in fact, a 'medically significant' epidemic of vitamin-D-deficient people," Holick says. Between 40% and 60% of Americans are seasonally or chronically vitamin-D deficient, he claims.

Other experts have also voiced concerns about vitamin-D deficiency. Late last year the issue was discussed at a conference organized by the US National Institutes of Health to assess the "alarming prevalence of low circulating levels of vitamin D in the US population." The meeting heard speculation that low levels of the vitamin could be due to a lower intake of vitamin-fortified foods, particularly milk and cereal; an increase in the use of sun block and decreased sun exposure; and an increase in the popularity of breast-feeding.

Even Gilchrest acknowledges that many people are vitamin-D deficient, but she says the risk is very small compared with the danger of melanoma, which is expected to strike 55 000 Americans this year. She says vitamin-D deficiency is "hardly an epidemic. What I see every single week is people with skin cancer."

"Consumers should be knowledgeable about the potential risk of skin cancer," Holick concurs, but he points out that "fewer than 0.5% of those who develop nonmelanoma skin cancer die, about 1200 people a year in the US."

In contrast, "mortality rates indicate that 150 000 people die of diseases that can be prevented by sensible sun exposure," he says.


  1. Holick M. May 2004. The UV Advantage 


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