August 14, 2008
Cancer Society wrong on melanoma risk
SUNLIGHT: THE BEST MEDICINE?
The Jury Is In
For three years now, sunsafe campaigners have been appealing for calm and "more research" before making "hasty" decisions about the dangers of UV rays. But now two new scientific studies have confirmed one of medical science's worst fears – sunsafe campaigns could actually be far more hazardous to your health than sunbathing. IAN WISHART, JOHN FAUBER and RON KOTULAK have the story
For two decades now, we've been told to slip, slop, slap; that the sun is dangerous and will kill us. We've encouraged an entire generation of kids to grow up with these secret fears, reinforced by politically-correct and well-intentioned community advertising campaigns. But all the way through, some things just didn't seem to gel. Firstly, humans have always had plenty of sun exposure in the past, yet it is only since the widespread use of sunscreens that skin cancer rates have appeared to rise.
In the early 1990s, a Norwegian Cancer Institute research scientist, Professor Johan Moan, made a staggering announcement in the British Journal of Cancer: while the annual incidence of melanoma in Norway had quadrupled between 1957 and 1984, there had been no corresponding change in the ozone layer over the region. "Ozone depletion is not the cause of the increase in skin cancers," his medical journal report notes.
As if to emphasise the rapid increase in skin cancer rates, the Norwegians re-analysed the data just a few years later and found the rates had grown again, a 600% increase in skin cancer between 1960 and 1990 – just thirty years! Yet still no change in ozone levels.
New Zealand and Australia – two of the countries that were first to latch on to the sunsafe message – now have the highest rates of melanoma in the world.
And it's not just skin cancer – other types of cancer have rocketed upwards as well. Until now, scientists have not made a connection between all these things, but that's all changing.
Two new scientific studies out this month have added to the growing mountain of evidence that our obsession with reducing sun exposure and slathering ourselves in sunscreen could actually be killing us. At the heart of the debate is vitamin D – a crucial ingredient, it now turns out, in the battle against a whole range of modern illnesses. Vitamin D is produced by the skin's exposure to the sun's "harmful" ultraviolet rays. If you protect yourself from UV rays by covering up all the time, chances are your body is not topping up its vitamin D storage banks. And the impact of that can be fatal.
One of the new studies shows a massive increase in the risk of heart disease among people who have low levels of vitamin D, while another shows increased sun exposure actually reduces your chances of dying from skin cancer!
What follows is a series of international reports on the latest discoveries and what they mean:
SUNLIGHT AND HEART DISEASE
Original study published: In the journal Circulation, January 08
At a glance:
Survey sample – 1,739 patients over five years
Conclusions – A 53% to 80% higher risk of heart attack or stroke in people with low levels of Vitamin D
Study ties heart ills, vitamin D deficiency
By John Fauber
MILWAUKEE - Low levels of vitamin D, a chronic problem for many people in northern latitudes, were associated with substantially higher rates of heart disease and stroke, according to the latest study in a growing amount of research suggesting that vitamin D deficiencies might be at the root of a variety of serious health problems.
Indeed, a second study published online Monday [see following story] in another journal concluded that people who got increased levels of sun exposure had a better chance of surviving various cancers than those who got limited sun exposure.
In one of the strongest studies to date linking the vitamin to cardiovascular disease, researchers followed 1,739 members of the Framingham Offspring Study for more than five years.
They found the rate of cardiovascular disease events such as heart attacks, strokes and heart failure were from 53 percent to 80 percent higher in people with low levels of vitamin D in their blood.
"This is a stunning study," says John Whitcomb, medical director of the Aurora Sinai Wellness Institute in Milwaukee. He was not involved in the study. Whitcomb says the study bolsters the idea that people should be supplementing their diet with vitamin D pills during autumn and winter. Whitcomb noted that other than eating lots of fatty fish, it is nearly impossible to maintain optimal vitamin D levels through diet alone. Sun exposure and taking vitamin D supplements are the only proven methods, he says.
"We were designed to live in sunshine," Whitcomb says. "Every year we go through this five-month stress test."
Because the study followed patients after their vitamin D levels were measured, it is more rigorous in design than other research that merely found a retrospective link between vitamin D levels and cardiovascular disease, says Denise Teves, an assistant professor of medicine at the Medical College of Wisconsin in Wauwatosa who was also not involved in the study.
"It makes perfect sense," she says. In patients she evaluates for possible osteoporosis at Froedtert Hospital and the Zablocki Veterans Affairs Medical Center, up to 90 percent have insufficient levels of vitamin D, Teves says.
Teves noted there are several reasons why vitamin D might help prevent cardiovascular disease. She says cells that line the arteries of the heart have vitamin D receptors. Low levels of vitamin D can lead to a proliferation of smooth muscle cells in those blood vessels, which, in turn, can lead to blockages and stiffness in arteries.
In addition, more vitamin D can lead to less inflammation in arteries. It also has been linked to reduced blood pressure. Teves says that while the current recommendation for adults is to get about 400 international units of vitamin D a day, an optimal level might be from 800 to 2,000 international units. However, other vitamins have shown initial promise in preventing cardiovascular disease only to fizzle out when randomized clinical trials were done, says Matthew Wolff, chief of cardiovascular medicine at the University of Wisconsin Hospital and Clinics in Madison.
Wolff, who was not involved with the study, says that people who take vitamins tend to lead healthier lives than those who don't and it is hard determine whether it is the vitamin or the lifestyle that is the root of the health benefit.
Still, Wolff says, there is a great deal of biochemical evidence that explains why vitamin D might be beneficial.
"We can't assume there is a therapeutic benefit from taking the vitamin," Wolff says. "It's just intriguing."
However, researchers say there may be one significant difference between vitamin D and vitamins such as C and E and folic acid, which have failed to show a benefit in reducing cardiovascular disease risk in randomized trials.
For much of history, humans lived near the equator and were exposed to higher amounts of ultraviolet light, resulting in higher levels of vitamin D in their bodies, says Thomas Wang, lead author of the cardiovascular risk and vitamin D study, which was published online this month in the journal Circulation.
"The levels we see today in developed countries are relatively unusual, especially from an evolutionary standpoint," says Wang, an assistant professor of medicine at Harvard Medical School.
One-third to one-half of otherwise healthy, middle-aged to older adults have low levels of vitamin D in the United States, the study says. The study found a significant reduction in cardiovascular disease risk in people who had more than 15 nanograms per millilitre of 25-dihydroxyvitamin D - the form of vitamin D stored in blood - compared with those who had less than that.
Wang says the benefit might have been even greater if the study had compared 15 nanograms per millilitre or less with at least 30 nanograms per millilitre, which many researchers believe is the optimal level of vitamin D.
Wang says his study doesn't prove that taking vitamin supplements reduces heart attacks and strokes. That can only be done with a large clinical trial in which vitamin D is compared with a placebo. However, until such studies are done, there is little risk for adults who take up to 2,000 international units a day, he says.
Over the last several years, numerous studies have found links between low levels of vitamin D, not just with bone health, but in various cancers, the flu, diabetes, multiple sclerosis and other neurological disorders.
The amount of vitamin D produced in the body as the result of sunlight is 3.4 times to 4.8 times greater below the equator than in the United Kingdom and Scandinavia, according to a separate analysis published online this month in the Proceedings of the National Academy of Sciences.
The researchers found that survival from various internal cancers improved with greater amounts of sun exposure. "It's at least a 30 percent reduction" in mortality, says senior author Richard Setlow, a biophysicist with the Brookhaven National Laboratory in Upton, N.Y. "It depends on the cancer."
Most of the work on the study was done in Norway.
SUNLIGHT AND REDUCED CANCER DEATH RATES
Original study published: In the Proceedings of the National Academy of Sciences, January 7th, 2008
At a glance:
Survey sample – mortality and cancer incidence data from NZ, Australia, UK and Scandinavia
Conclusions – "Increased sun exposure may lead to improved cancer prognosis and, possibly, give more positive than adverse health effects"
SUNLIGHT HELPS YOU SURVIVE CANCER
By Ian Wishart
For most New Zealanders, the release of this major study got lost in the silly season. The lead author on the report, Norway's Johan Moan, is the man whose 1992 study found that ozone holes were not the cause of skin cancer. This time around, he and his team have compared skin cancer data from New Zealand and Australia, with the same statistics in the Northern Hemisphere. They chose racial and skin types that are closely related genetically, in order to get the best possible comparison. What they found is, quite simply, stunning.
While those of us downunder suffer much higher melanoma rates than our colleagues in the north, our survival rates are – paradoxically – much higher on a victim-for-victim comparison. The same applies to internal cancers like breast, prostate or colon – although we suffer higher rates, we are also more likely to survive them.
Australians, who get more sun than kiwis, are more likely to survive their cancers than New Zealanders are, lending further weight to the theory.
What remains up in the air is the exact cause of many of these cancers. Modern diets are full of agricultural chemicals, with one Spanish study published this month finding every single Spanish citizen (100% of the study sample) has one or more agricultural pesticides circulating in their blood at significant levels. New Zealand and Australia, as heavy agricultural producers may have correspondingly higher cancer rates for that reason. Even so, sunlight appears to have a significant impact in helping us survive the cancers that we do get.
Even the science on the exact cause of melanoma is not settled, with the latest report highlighting the arguments against solar radiation being the main cause:
"The main arguments against the concept that sun exposure causes cutaneous malignant melanoma (CMM) are that: 1) CMM is more common among persons with indoor work than among those people with outdoor work; 2) in younger generations, more CMMs arise per unit skin area on partly shielded areas (trunk and legs) than on face and neck; and 3) CMMs sometimes arise on totally shielded areas [soles of feet, palms, inside the eyeball]."
Nonetheless, the PNAS study suggests that a "significant fraction" of malignant melanomas may be caused by sun exposure.
No mention is made, however, of the possible effect of the chemicals in sunscreens themselves.
"Most chemical sunscreens contain from 2 to 5% of benzophenone or its derivatives (oxybenzone,benzophenone-3) as their active ingredient," reports researcher Hans Larsen.
"Benzophenone is one of the most powerful free radical generators known to man. It is used in industrial processes to initiate chemical reactions and promote crosslinking. Benzophenone is activated by ultraviolet light. The absorbed energy breaks benzophenone's double bond to produce two free radical sites. The free radicals desperately look for a hydrogen atom to make them "feel whole again". They may find this hydrogen atom among the other ingredients of the sunscreen, but it is conceivable that they could also find it on the surface of the skin and thereby initiate a chain reaction which could ultimately lead to melanoma and other skin cancers.
"Researchers at the Harvard Medical School have recently discovered that psoralen, another ultraviolet light-activated free radical generator, is an extremely efficient carcinogen. They found that the rate of squamous cell carcinoma among patients with psoriasis, who had been repeatedly treated with UVA light after a topical application of psoralen, was 83 times higher than among the general population."
In other words, how much of the slip, slop, slap – particularly when the campaign began two decades ago with lower grades of sunscreens – might actually be the real cause of skin cancer outbreaks today?
Leaving aside the cause, however, the PNAS study has some breakthrough data on cancer survival rates. If your vitamin D levels are high, you are around 30% more likely to survive "prostate, breast, colon and lung cancers, as well as lymphomas and even melanomas," reports the study.
"Other investigators have found comparable results. These data argue for a positive role of sun-induced vitamin D in cancer prognosis, or that a good vitamin D status is advantageous when in combination with standard cancer therapies."
Unfortunately, this protective effect cannot be guaranteed using vitamin D supplements.
"Our recent investigations…show that a high sun-bed induced [vitamin D] level cannot be maintained by daily intakes of the recommended amount of vitamin D (200 units in the form of cod-liver oil pills).
"Thus we conclude that…the sun is an important source of vitamin D…So far, epidemiological data for cancer argue for an overall positive role of sun-induced vitamin D. There may be more beneficial than adverse effects of moderately increased sun exposure, even for total cancer mortality."
Of course, as with all things, there is a trade-off between increasing sun exposure for your family's health, and increasing the risk of skin cancer. But the numbers tell the story: In 2004, 7,900 Americans died of melanoma. On the flip side of that coin, 45,000 Americans are believed to have died from cancers that they could have survived with greater exposure to the sun. In other words, you are nine times more likely to die from cancer caused or aggravated by a lack of sunlight, than you are from skin cancer caused by sunlight.
THE OVERVIEW: Vitamin D - Cheap wonder drug?
By John Fauber
MILWAUKEE - It seems too simple to be true: Expose most of your body to about 15 minutes of sunlight a day during the summer and take large doses of inexpensive vitamin D pills during the winter and maybe, just maybe, you will substantially reduce the risk of getting various cancers, the flu, diabetes, heart disease, autoimmune diseases and neurological disorders.
A flurry of research in the last few years suggests that low levels of vitamin D, a fairly common occurrence in those who live in northern locales much of the year [or the southern latitudes of New Zealand in the southern hemisphere], may be partly to blame for much of the ill health of many people.
"Vitamin D is not just for bones anymore," says Hector Deluca, a pioneering vitamin D researcher at the University of Wisconsin-Madison. "The questions are: How much do we take and do we expose ourselves to sunlight?"
Deluca noted that the vitamin plays a role in shutting down or activating at least 100 genes, many of which are involved in preventing diseases.
Consider these recent developments:
-A small observational study by University of Wisconsin researchers published online in January 2007 showed a significant association between low levels of vitamin D in the blood of Alzheimer's patients and poor performance on a cognitive test. The study was prompted after family members of the Alzheimer's patients reported how well they were performing and acting within weeks of being put on large doses of prescription vitamin D, says lead author Robert Przybelski, an associate professor of geriatric medicine at the University of Wisconsin.
"We hypothesize that good vitamin D levels might prevent or mitigate the disease," Przybelski says.
The study noted that neurons, like many other cells, have vitamin D receptors. It says vitamin D might enhance levels of important brain chemicals and that it also might help protect brain cells.
- Last February, an analysis in the American Journal of Preventive Medicine looked at vitamin D levels in the blood and concluded that daily intake of 1,000 to 2,000 international units of the supplement could reduce the incidence of colorectal cancer by about 50 percent with little risk. The current recommended intake ranges from about 200 IU in children to 600 IU in the elderly.
- Also that month, many of the same researchers concluded in a separate analysis that intake of 2,000 IU of vitamin D and, when possible, about 12 minutes a day of sun exposure could reduce the incidence of breast cancer by about 50 percent.
Vitamin D has the potential to reduce at least half of serious invasive cancers and make the remaining ones milder and far more treatable, says Cedric Garland, a co-author on both papers and professor of family and preventive medicine at the University of California-San Diego and the Moores Cancer Center.
Garland and others have estimated that 15 minutes a day of sun exposure would prevent 10 cancer deaths for every one skin cancer death it would cause.
-In December 06, a study involving 7 million whites in the U.S. military found that those with the highest levels of vitamin D in their blood were 62 percent less likely to develop multiple sclerosis years later than those with low levels of the vitamin.
The study echoes earlier research showing that MS, the most common nerve disease among young adults, is much less common in people who live closer to the equator.
-Even seasonal flu now is being linked to the lack of sun exposure that occurs each year at northern latitudes.
A September 06 review article in the Epidemiology of Infection noted how seasonal flu peaks dramatically between November and February [the northern winter] while, at about the same time, vitamin D levels in the blood drop off substantially, a decline attributed to the lack of sun exposure that occurs during winter months. Vitamin D is synthesized in skin when it is exposed to ultraviolet radiation.
The paper noted that vitamin D, which is considered a steroid prehormone, plays a profound role in regulating the immune system. It dramatically stimulates the expression of anti-microbial substances in cells lining the surface of the respiratory tract and it helps prevent over-production of inflammatory substances produced by certain immune system cells.
The paper says a lack of sun exposure during the winter also may contribute to susceptibility to other respiratory viral infections, including many of the more than 200 viruses that cause the common cold.
And the older a person gets, the more susceptible they are.
Although sun exposure can produce huge amounts of vitamin D, the elderly make only about 25 percent as much of the vitamin D in their skin as a 20-year-old who is exposed to the same amount of sunlight.
Blacks also are significantly less able to convert sunlight to vitamin D in their skin. Vitamin D shots?
"Vitamin D may be the most potent antibiotic that exists," says lead author John Cannell, a psychiatrist at Atascadero State Hospital in California and executive director of the non-profit Vitamin D Council. "Maybe the shot people need to get in the fall is not a flu shot, but a vitamin D shot. Our ancestors got it every day in Africa."
Given the strong body of evidence linking excessive sun exposure to skin cancer, taking a supplement might be the safest way to increase vitamin D levels.
While 15 to 20 minutes a day probably will not lead to a significant increased risk of skin cancer, the risk will vary depending on whether the person is fair-skinned and the time of day they are exposed, says Thomas Russell, interim chairman of the dermatology department and clinical professor of dermatology at the Medical College of Wisconsin.
Russell argues a more sensible approach for adults, in his view, is to take an additional 1,000 to 2,000 IU a day with supplements.
"There is no definite answer about how much sun you can tolerate," Russell says. "If you are trying to generate vitamin D, just take it by mouth."
Indeed, a growing number of researchers now are saying that taking up to 2,000 IU a day, and possibly more, is safe for adults.
The Institute of Medicine says that is the tolerable upper limit, or the highest daily intake that is likely to pose no adverse health risks for a healthy adult.
Researchers say exposure to intense sunlight was mostly a year-round occurrence for our prehistoric ancestors who, for eons, existed naked near the equator. It has been only in relatively recent human evolutionary history that people moved north, began wearing clothing and spent more time indoors, resulting in vitamin D deficiencies.
But whilst there is a risk of vitamin D overdose when taking oral supplements, it is impossible to overdose on vitamin D through sun exposure. This, say researchers, is because the human body is designed to process sunlight-induced vitamin D easily, whereas megadoses taken orally are not natural and not as easily processed by the body.
SUNLIGHT AND OTHER DISEASES
By Ronald Kotulak
CHICAGO - Emerging research indicates that vitamin D is more important to our health than previously thought, leading an increasing number of scientists to challenge whether the fear of sun exposure has made us cover up too much.
Doctors are finding an increase in vitamin D deficiencies, even as researchers discover remarkable results from the vitamin that affects nearly every tissue in the body.
When women took vitamin D in multivitamin supplements over a long period of time, their risk of developing multiple sclerosis was reduced by 40 percent. And a disturbing number of children who don't have enough vitamin D in their bodies are showing up with rickets, a crippling bone disorder thought to have been eradicated more than 70 years ago.
Dr. Craig Langman, a kidney and mineral metabolism expert at Children's Memorial Hospital and Northwestern University Medical School, sees a new case of rickets every week, triple the rate of five years ago.
"We're finding more and more kids are presenting with evidence of vitamin D malnutrition," says Langman, who noted that includes fractures and bone pain.
In New Zealand, studies at Starship Hospital found 10% of infants under the age of 2 are vitamin D deficient, whilst 87% of pregnant women in a Wellington study were also found to lack sufficient levels of vitamin D. Cases of rickets are turning up in New Zealand and Australian hospitals with more frequency, even though we have some of the highest UV levels in the world. In other words, we're covering up so well and avoiding the sun so much, that these diseases are making an appearance, even here.
Vitamin D is a critical hormone that scientists are discovering helps regulate the health of more than 30 different tissues, from the brain to the prostate. It plays a role in regulating cell growth, the immune system and blood pressure, and in the production of insulin, brain chemicals and bone.
"We thought that vitamin D was a very narrow-acting substance," says Dr. Hector DeLuca of the University of Wisconsin, where vitamin D was first identified in the early 1900s, leading to the fortification of milk and some other foods that eliminated endemic rickets.
"The big surprise is that it's got a lot of important biological effects that probably contribute to our health and we're just now beginning to uncover them," says DeLuca. "Are we getting enough vitamin D? No we're not, especially in the winter."
Vitamin D is one of the body's many control systems. It acts like an emergency brake that helps stop cells from perilously misbehaving, as immune cells can do when they cause such autoimmune diseases as multiple sclerosis and as breast and prostate cells do when they turn cancerous.
This protection declines as vitamin D levels drop. University of Chicago microbiologist Yan Chun Li discovered just how that happens with high blood pressure. Vitamin D helps normalize blood pressure by keeping a pressure-increasing switch called renin in check.
Vitamin D's importance for health goes back more than 750 million years to the earliest life forms that left the ocean for the Earth's surface. All vertebrates today depend on sun exposure for vitamin D production.
The lack of vitamin D is known to cause rickets, osteoporosis and osteomalacia (soft bones). New research indicates that vitamin D malnutrition may also be linked to many chronic diseases such as cancer (breast, ovarian, colon and prostate), chronic pain, weakness, chronic fatigue, autoimmune diseases like multiple sclerosis and Type 1 diabetes, high blood pressure, mental illnesses - depression, seasonal affective disorder and possibly schizophrenia - heart disease, rheumatoid arthritis, psoriasis, tuberculosis and inflammatory bowel disease.
"A lot of people with aches and pains and marginal weakness could be helped by vitamin D supplements," says Dr. Paresh Dandona of the State University of New York at Buffalo who reported the first five cases of vitamin D deficient myopathy three years ago in the Archives of Internal Medicine.
Undiagnosed pain is the chief complaint of more than one-third of patients.
Studying 150 children and adults with undiagnosed pain, Dr. Greg Plotnikoff of the University of Minnesota discovered that 93 percent were severely or profoundly vitamin D deficient. All were put on prescription doses of the vitamin.
"One patient with chest pain had multiple balloon angioplasties and his pain never went away," Plotnikoff says. "He also had surgery for his low back pain but he didn't get any better.
"I measured his vitamin D level and it was basically zero," he says. "His chest and low back pain were not due to cardiac or spinal disease but to low vitamin D. We put him on prescription strength vitamin D and he got much better. We had spent over $200,000 on him in the hospital for these other procedures without doing a $20 blood test."
A study in the British medical journal Lancet found that infants receiving 2,000 IU of vitamin D daily were protected from developing Type 1 diabetes. Various forms of vitamin D have become a major treatment for psoriasis and preliminary evidence suggests it reduces blood pressure, reduces hip fracture risks in older people and improves symptoms of rheumatoid arthritis and multiple sclerosis.
"Our study supports a possible role for vitamin D in the prevention of MS," says epidemiologist Kassandra Munger of the Harvard School of Public Health. "Further studies are needed to confirm the findings, but taking a multiple vitamin as part of a healthy diet can't hurt."
Researchers are finding that the current recommended daily allowances of vitamin D - ranging from 200 international units for infants, children and adults up to age 50 years; 400 IU for men and women from 50 to 70; and 600 IU for people older than 70 - are probably far lower than the minimum amount necessary for optimum health.
Scientists are quick to warn that although people may need more vitamin D, mostly in the form of supplements in higher latitudes where sunlight is weak during winter months, they should consult a physician before consuming large doses. Taking too much vitamin D can elevate levels of calcium in the blood, a potentially serious condition that can lead to nausea, vomiting, or even death. It is especially easy for children to overdose on vitamin D supplements.
Dr. Michael F. Holick of Boston University Medical Center, one of the world's foremost vitamin D experts, recommends 1,000 IU daily for everyone through a combination of safe exposure to sunlight and supplements.
Summertime sun exposure on the face, arms and hands around noon for only five to 15 minutes for people with light skin two to three times a week provides sufficient vitamin D, he says.
Blacks have the highest risk for vitamin D deficiency because dark skin needs five to 10 times more sunlight than white to produce the same amount of the vitamin. One study found that 42 percent of African-American women in the U.S. were vitamin D deficient.
Chronic diseases associated with vitamin D deficiency are 25 to 50 percent more frequent in northern climates than among people living closer to the sunny equator, where humans first evolved. As people migrated away from the equator, it is thought, skin evolved lighter shades to absorb more sunlight for vitamin D production.
Vitamin D is not available in most foods (oily fish, egg yolks, liver and cod liver oil have some), but it is abundantly made when sunlight strikes the skin, which normally produces about 90 percent of the body's store of the vitamin.
People living in high northern hemisphere or low southern hemisphere latitudes don't get enough sun in winter to make vitamin D. A person living in Chicago, Boston, Detroit or New York can stand naked outside all day in the winter and not make any vitamin D, says Holick, author of "The UV Advantage."
Even in summer the skin's vitamin D-making ability gets dampened from the increasing use of sunscreen, leading a growing number of health experts to challenge the advice given over the last two decades to avoid the sun at all costs in order to reduce skin cancer risk.
"The amount of vitamin D in our diet is totally inadequate," Holick says. "We are in an era of sunphobia - that is not being exposed to any direct sunlight - that's being promoted widely by the dermatology community and it's probably hurting people's health more than it's helping them."
"That message needs to be modified and moderated to a more sensible approach so that people can get a little bit of safe sun," he says.
The evidence is overwhelming that excessive sun exposure causes skin cancer. More than 1 million cases of squamous and basal cell cancers, which are highly treatable, are expected this year, according to the American Cancer Society. Solar exposure is also blamed for the anticipated 55,100 cases of melanoma in 2004 and 7,910 deaths. Melonama, a potentially deadly skin cancer, usually occurs years after severe sunburns in childhood.
On the other hand, increasing evidence suggests that adequate vitamin D levels from healthy sun exposure may reduce the risk of many other cancers.
A recent study of more than 430,000 death certificates showed that people who had more exposure to sunlight had a 26 percent lower risk of death from colon and breast cancer, says D. Michal Freedman, an epidemiologist at the National Cancer Institute.
Testifying at a "Vitamin D and Health in the 21st century" conference called by the National Institutes of Health's Office of Dietary Supplements, William B. Grant, a retired NASA senior scientist and solar radiation expert, says his studies determined that lack of vitamin D accounts for 45,000 cancer deaths annually and 165,000 new cancer cases.
The conference was prompted by growing concerns of widespread vitamin D inadequacy and how to strike a balance between supplements, dietary fortification, tanning booths and sun exposure, says NIH nutritionist Mary Frances Picciano.
"If you go to the literature where people are talking about sunlight and cancer risk, nobody mentions that you need sun for vitamin D," she says. "By the same token if you go to the vitamin D literature where people are talking about skin irradiation to get vitamin D, nobody talks about cancer.
"One of the first things that might be necessary is to get the skin cancer people together with vitamin D requirement people," Picciano says. "There are questions that need to be addressed before meaningful public health policy can go forward."
New research puts a greater importance on vitamin D, which the body develops from sunlight exposure. Vitamin D's main function is to maintain normal levels of calcium and phosphorus in the blood.
THE NZ CANCER SOCIETY'S POSITION:
By Ian Wishart
So where does all this leave the sunsafe campaign in New Zealand? The writing in regard to vitamin D has been on the wall for several years now, as study after study shows the impact of slip slop slap on our wider community health. While skin cancer rates are falling overall, far more of us are now dying from other conditions caused by the lack of sun exposure than have ever been killed by skin cancer. Have we failed to see the wood for the trees?
For two years, now, the NZ Cancer Society has been evaluating the new data, occasionally updating its official position through a statement on its website. The latest of those statements contains the following assertion:
"Our melanoma incidence and mortality rates, which are among the highest in the world.."
As a point of fact, they are not. Whilst our incidence of melanoma is second only to Australia, the ratio of deaths compared to the number of people developing the disease is far lower in NZ and Australia than anywhere else in the world. If you develop melanoma in NZ, your hope of survival is greater here than in, say, Britain. And at the risk of laboring the point, according to the latest science, that's because the very same sunlight that allegedly causes melanoma conversely gives us some built in protection against its fatal effects.
The Cancer Society is in an interesting position – being an advocate for all types of cancer, not just melanoma. But it is also a commercial business, making money from the sales of its branded sunscreen products. Based on the scientific studies, more than 2,000 New Zealanders are dying each year from cancers they could have survived if they'd had greater sunlight exposure every day. Weighing the data in the balance, a safety campaign designed to reduce our 240 or so melanoma deaths per year, which backfires and kills a further 2,200 people by worsening their health, would seem to be a hollow victory. That's equivalent to an incredible five times the road toll! A 50% reduction in breast cancer rates among women who sunbathe more will save far more women than the few who will develop skin cancer.
And that doesn't even factor in the costs of up to 80% more heart disease caused by low vitamin D levels – heart disease being New Zealand's biggest killer.
To be fair to the Cancer Society, it has tried to get its head around the problem, as its latest position statement discloses.
"The Cancer Society of New Zealand has supported sun protection and skin cancer control research and activities since the 1980s. The links between excessive sun exposure and skin cancers and, in particular, intermittent episodes of sunburn in childhood and adolescence and melanoma, are clearly established. However, in recent years there has been an increasing body of research which examines the beneficial aspects of sun exposure, in addition to those already known for musculoskeletal health, mainly in relation to human synthesis of vitamin D.
"In 2005, recognising the need to balance both the risks and benefits of sun exposure in public health messages, the Cancer Society convened a forum of experts from a range of organisations and disciplines, including dermatology, bone health, immunology, nutrition, climatology, and social and behavioural research. This resulted in the development of The Risks & Benefits of Sun Exposure in New Zealand Position Statement (www.cancernz.org.nz/HealthPromotion/SkinCancerControl/VitaminD.
"In July 2007, the Society again brought together a multi-disciplinary expert advisory group with the key objectives of 1) reviewing new evidence on vitamin D, sun exposure, & health and 2) revising the current position statement. The Society commissioned Robert Scragg (Associate Professor of Epidemiology, Auckland University School of Population Health) to undertake a review of vitamin D, sun exposure (solar ultraviolet radiation or UVR) and cancer.
"A key conclusion of this commissioned review was that there was "strong evidence that vitamin D, through sun exposure or dietary sources, protects against colorectal cancer".
"However, other epidemiologists have queried the strength of this protective effect, given the quantity and quality of evidence currently available.
"Recognising the contested nature of these findings, the Cancer Society believes that the key conclusion of the commissioned review is "hypothesis generating" and, therefore, requires further research."
Now, remember, this was back in July last year. The two dynamite medical studies just published were not out then. Given that the sunsafe campaign may actually be killing thousands more New Zealanders than it could ever save, perhaps it is time for the Cancer Society to urgently review its entire strategy, especially when you consider that the current "cancer statistics" document on the society's website, published in October last year, actually lists sunlight as a cause of cancer:
"Other potentially avoidable causes of cancer include dietary factors, alcohol and sunlight."
It would appear the sunlight is actually saving far more people than it harms. Sunburn is still something to avoid at all costs, but researchers now recommend developing a moderate tan early in the season so as to maximize the body's inbuilt protection against skin cancer whilst allowing plenty of vitamin D to be processed. Fifteen minutes of noonday sun in summer is the maximum exposure needed
BREAKOUT BOX 1
AT A GLANCE
The Scientific Findings:
You are up to 80% more likely to suffer heart attack or stroke if your vitamin D levels are low.
Up to 50% lower risk of developing breast cancer if you get 15 minutes of direct sunlight a day, with vitamin D supplements in winter.
If you get breast cancer, and your vitamin D levels are good, you have a 30% better chance of survival. Remember that 87% of pregnant women in a Wellington survey, however, were found to be vitamin D deficient, so don't assume your levels are good.
Colorectal and other internal cancers
A 50% reduction in the risk of developing the disease, and again a 30% better chance of surviving if vitamin D levels are high.
A 40% reduction in the risk of developing the disease if you get plenty of direct sun exposure as a child. A study of seven million US servicemen over a number of years found a 62% reduction in the risk of MS among those with higher levels of vitamin D in their youth.
Type I Diabetes
Taking vitamin D during pregnancy can help prevent the development of diseases later in the unborn child's life, according to Armin Malter of Germany's Professional Association of Gynaecologists.
"The latest studies show that vitamin D can aid the immune system and help prevent auto-immune conditions such as diabetes and thyroid problems," says Malter, who adds that pregnant women are likely to have a deficiency of vitamin D as their unborn child develops in the womb and need to either get sunlight, or take supplements.
Over 70 percent of seemingly healthy teenage girls may be vitamin D deficient, says a British study, and are at increased risk of osteoporosis and other health problems later in life. Such results may lead to recommendations in certain countries of vitamin D supplementation for adolescents to help reduce the risk of osteoporosis. "Vitamin D deficiency during childhood and adolescence might impair the acquisition of peak bone mass at the end of skeletal growth and maturation, thereby increasing the risk of osteoporosis fracture in later life," explained the researchers from Saint Mary's Hospital for Women and Children in Manchester.
SIDEBAR BOX AT THE END
VITAMIN D SOURCES
-Sunlight: Ultraviolet rays trigger the formation of vitamin D in the skin, accounting for 90 percent of the daily recommended intake. 5 to 10 minutes of sun exposure between 10 a.m. and 2 p.m. daily in the summer are recommended. Particularly in southern areas of NZ and Australia, it is difficult to produce in the winter.
-Foods: Milk and cereals are fortified, and will say so on the packet if they contain extra vitamin D. Oily fish naturally contain vitamin D.
FOOD SOURCE INTERNATIONAL UNITS
Cod liver oil (1 tbs.) 1,360
Salmon, cooked (90gms) 360
CURRENT DAILY ALLOWANCE RECOMMENDATIONS
In international units (IU), by age
50 to 70: 400
Older than 70: 600
Many vitamin D experts recommend 1,000 IU daily for everyone.
Vitamin D-related health risks
Rickets: A disease in which children's bones soften, break.
Osteopororis: A condition characterized by fragile bones.
Osteomalacia: A bone-thinning disorder in adults that is similar to rickets.
Vitamin D malnutrition is now being linked to diseases such as cancer, multiple sclerosis, Type 1 diabetes, strokes, cardiovascular disease, heart attacks and high blood pressure.
Sources: US National Institute of health, National Osteoporosis Society