Photo from SunWerks Tanning
There is very little counter voice to the American Academy of Dermatology’s zero tolerance stance on exposure to sunlight. Its website says, “You need to protect your skin from the sun every day, even when it’s cloudy.” There is nothing good about the sun and even the one benefit – vitamin D – can better be supplied by taking pills rather than risking skin cancer.
In addition, taking lots of vitamin D doesn’t do that much for you. A huge study of people taking high doses of vitamin D didn’t demonstrate any benefit, relegating vitamin D supplementation to the host of other nutritional hopefuls that failed miserably like vitamin A and C.
I love the great outdoors and am a fan of vitamin D, so I did a little research into the science behind the medical community’s allergy to sun. Just how much greater is the risk of skin cancer to those who spend copious amounts of time outside? Is it true that the best scientific evidence shows no benefit from vitamin D supplementation?
Supplements are a $30 billion market in the US. Despite the commercial support and popularity, study after study has failed to show any benefit to taking vitamin A, vitamin C, vitamin E, selenium, beta-carotene, glucosamine, chondroitin, and fish oil beyond the amounts one can get in a plant-based, whole foods diet.
But vitamin D held more promise. People with low levels of vitamin D in their blood have much higher rates of cancer, diabetes, obesity, osteoporosis, cardiovascular disease, stroke, depression, cognitive impairment, and autoimmune disorders. Dihydroxycholecalciferol – vitamin D3 – is essential for calcium absorption and bone health, but the association of lower levels of vitamin D with so many diseases led medical researchers to investigate its role in other biological processes.
They suspected that most people weren’t getting enough. Vitamin D isn’t really a vitamin at all, but a cholesterol-based hormone produced through sunlight on the skin with a little help from the kidneys. It is hard to get enough through diet alone. Vitamin D deficiency is more pronounced in northern populations that bundle up and spend most of their time indoors. When our tropical ancestors lived naked outdoors, getting enough vitamin D wasn’t a problem.
But today most of us modern, civilized humans have indoor jobs, and when we do go outside, we’ve been cautioned to protect ourselves from dangerous ultraviolet light, which causes skin cancer. Sunscreen also prevents our skin from making vitamin D, but that’s fine, they tell us. We get enough in our foods which have been fortified with all the vitamins and minerals we need.
When I did my master’s in nutrition in the 1970s, the recommended daily allowance of vitamin D (and it could be either D3 from animal sources or D2 – ergosterol from yeast) was 400 IU for adults and 800 for pregnant or lactating women. The literature was virtually devoid of case studies of vitamin D overdoses, though theoretically one could get too much of this oil soluble vitamin just as one can overdose on vitamin A.
Vitamin D supplementation has largely failed to demonstrate any benefit in clinical trials. A recent large and rigorous trial in which 25,871 participants received high doses for five years—found no impact on cancer, heart disease, or stroke. (https://www.nejm.org/doi/full/10.1056/NEJMoa1809944)
I would suggest that the amounts studied and referred to as “high dose” are really not that high. The study I just mentioned administered 2000 IU a day, which when compared to 400 IU a day, sounds like a lot. But the blood levels were not checked, which is important. In smaller clinical trials, the really impressive results including activation of natural killer cells which are particularly important in fighting cancer, only happen when blood values exceed 50 ng%. Two thousand IU a day would barely move the value above 30 ng% in most people.
A personal aside: I take 5000 – 10,000 IU of vitamin D a day to keep my levels above 50 ng%. Age management physicians generally shoot for values between 50 and 100 ng%. In my entire career as a nutritionist and physician, I have only encountered one case of hypervitaminosis D where the blood level exceeded 120 ng% in a woman who was taking 50,000 IU a day for many months!
I say this to support my professional opinion that robust vitamin D supplementation has merit and the risk of overdose is minimal and easily avoided.
So what about the risk of cancer from sun exposure? Skin cancer kills fewer than three per 100,000 in the U.S. each year. That’s one person compared to a hundred in the same population who die from cardiovascular disease.
Moreover, not all skin cancers are equal. By far the most common are basal-cell and squamous-cell carcinomas, which are almost never fatal. Melanoma, a truly deadly type of cancer, is much rarer, making up only one to three percent of new skin cancers.
Strangely, outdoor workers have only half the melanoma rate of indoor workers. Tanned people have the lowest rates over all. The real risk factor for melanoma seems to be pale people getting sunburned, especially when young. Long-term regular sun exposure is associated with less melanoma.
Don’t get me wrong. Melanoma is deadly and most cases are due to UV exposure. You need to be cautious. But how do we explain people spending regular time in the sun having less melanoma than those who avoid it?
At Sweden’s Karolinska Institute they tracked the sunbathing habits of nearly 30,000 Swedish women over 20 years. Initially, they found that women who spent more time in the sun, especially in the summer, suffered fewer blood clots. Then they discovered these women had lower rates of diabetes as well.
Finally, they looked at skin cancer. The sun-loving women had a higher incidence, but they were eight times less likely to die from melanoma.
When they looked at the overall mortality rates, they were astounded. The mortality rates of the sun avoiders over the 20 years of the study, were twice as high as for the sun lovers.
Not many lifestyle choices will double your risk of dying. Avoiding sun exposure is a risk factor to life expectancy similar in magnitude to smoking.
Recent research has uncovered a possible explanation to resolve the conundrum of why exposure to sunlight causes more cancer but lowers its death rate. In 2010, while researching nitric oxide, Richard Weller, a dermatologist at the University of Edinburgh, discovered a biological pathway through which the skin uses sunlight to make nitric oxide, or NO. NO is a molecule produced by the body that lowers blood pressure by dilating blood vessels. It was already well known that rates of high blood pressure, heart disease, stroke, and overall mortality all increase the farther north you live and are most pronounced in the winter. Weller asked the question whether exposing skin to sunlight could lower blood pressure.
When he exposed volunteers to the equivalent of half an hour of summer sunshine without sunscreen, their nitric oxide levels rose and their blood pressure fell. High blood pressure is a leading cause of early death worldwide due to its effect on cardiovascular and cerebrovascular pathology. The reduction in blood pressure due to simply exposing the study population to 30 minutes of sunlight a day was large enough to prevent millions of deaths on a global scale.
An even larger study is due to be published later this year. Weller’s team has tracked the blood pressure of 340,000 people in 2,000 spots around the U.S. for three years, adjusting for variables such as age and skin type. The results demonstrate that the reason people in sunnier environments have lower blood pressure is no more complicated than exposing skin to sunlight.
Homo sapiens have been around for a couple hundred thousand years. Until only recently, we lived outside. How did we make it through the Stone Age without sunscreen?
If vitamin D production and NO to lower blood pressure were not enough benefit, it now looks like sunshine triggers the release of other important compounds including serotonin and endorphins. Exposure to sunlight is also associated with a reduced risk of prostate, breast, colorectal, and pancreatic cancers. It governs circadian rhythms. It reduces inflammation and autoimmune response. It has a positive effect on a host of mental conditions.
Oh, and it’s free.
This all sounds like good news, but it is important to keep in mind that not everyone processes sunshine the same way. The current guidelines were written largely by white people for the whitest of the indoor-dwelling white. For example, Addis Ababa, which is near the equator and sits above 7,500 feet, receives high amounts of UV radiation. Despite that, skin cancer is rare.
Early humans evolved outdoors under the tropical sun. They evolved a way to protect our skin from too much radiation in the form of melanin, our natural sunscreen. They never had to worry about the sun.
As humans moved farther from the tropics, they evolved to produce less melanin. They also evolved to create more of a protein for storing vitamin D. They developed the ability to build up a suntan when needed as the sun got more intense in the spring.
Sunburn was probably rare until recently. It tends to happen when pasty-white cubicle-dwellers hit the beach in the summer unprepared. This is a virtual recipe for melanoma.
Darker-skinned people rarely get melanoma. For Caucasians, the rate is 26 per 100,000. But it is only 5 per 100,000 in Hispanics, and 1 per 100,000 in African Americans. When African Americans do get melanoma, it’s usually the kind that occurs on the palms, soles, or under the nails and not caused by sun exposure.
African Americans suffer from high rates of diabetes, cardiovascular disease, cancer, and other diseases that improve in the presence of sunshine. They may not be getting enough. Because Blacks have more sun blocking melanin, they may need more sun exposure to produce vitamin D, which they are also less able to store.
Dark-skinned people have much to gain and little to fear from the sun.
Capitalism steps in
Despite that, the cosmetics industry is targeting people of color for sunscreen. The marketing ploy is supported by the American Academy of Dermatology whose website states: “The American Academy of Dermatology recommends that all people, regardless of skin color (italics mine), protect themselves from the sun’s harmful ultraviolet rays by seeking shade, wearing protective clothing, and using a broad-spectrum, water-resistant sunscreen with an SPF of 30 or higher.”
One of the weaknesses of a profit-based healthcare system (of which the US is virtually the only one in the developed world) is the influence industry can exert on medical authority. It’s not my purpose here to rehash the complexities of our system. If you want more of that, please see my book, “Outsider – My Career in Medicine” by Lloyd Sparks, MD. But other nations seem less influenced by advertising money and produce more common sense advice for their fellow citizens.
Australia provides an example of a much more nuanced and, in my opinion, more useful recommendation. Cancer Council Australia’s official position, which is endorsed by the Australasian College of Dermatologists, states the following:
“Ultraviolet radiation from the sun has both beneficial and harmful effects on human health.... A balance is required between excessive sun exposure which increases the risk of skin cancer and enough sun exposure to maintain adequate vitamin D levels.... It should be noted that the benefits of sun exposure may extend beyond the production of vitamin D. Other possible beneficial effects of sun exposure… include reduction in blood pressure, suppression of autoimmune disease, and improvements in mood.” (https://www.nejm.org/doi/full/10.1056/NEJMoa1809944)
When the UV index is below 3, which is typical for most of the United States in winter, sunscreen is not recommended unless near snow or some other reflective surface. The experts all agree that sunburns, especially in childhood, put a person at increased risk of melanoma.
But besides taking sensible precaution against sunburn, there is little to fear and much to love about sunshine.
And the aging effect of sunlight?
Yes, excessive exposure to UV radiation leads to dry, leathery skin even if the danger of cancer isn’t as bad as once thought. Each individual must consider their own situation with respect to season, latitude, skin pigmentation, personal history, and taste. One size does not fit all. Not even close.
· Skin health is not enhanced by compulsive covering. Air and sunlight are the best protections against rashes and skin diseases that thrive in dark, damp environments.
· Most of us would benefit from a lot more vitamin D.
· The risk of skin cancer is minimal and worth it compared to the benefits.
So, push yourself away from the computer screen, get out of your clothes and get your bare skin out in the fresh air every day. I do.