By Dr. Mercola
How is it that sunlight, once regarded as a divine power in some cultures, has come to be classified as a Class 1 carcinogen by the World Health Organization (WHO)? This is a question posed by photobiologist Dr. Alexander Wunsch, CEO of Medical Light Consulting in Heidelberg, Germany.
It's a fundamental one because it shows the dichotomy between sunlight in ancient and modern cultures. Once revered as a healing power, today sunlight is blamed for disease and humans are urged to largely shun this natural element.
In the video above, Wunsch explores sunlight from a historical perspective, including how both public and medical opinions of sunlight have changed dramatically over time. He says:
"Nowadays, sunlight is not fashionable anymore. Some experts even try to ban the tan, others work on restrictions, the U.S. Surgeon General issues a call to action on UV and tanning. How can we deal with these dark clouds in a formerly sunny sky?
Knowing more details about the past can help us to adjust and normalize the extreme positions of the 'no sun policy' advocated by the World Health Organization (WHO), the anti-cancer associations and many dermatologists."
Sunlight Used to Combat 'Diseases of Darkness'
Sunlight was used for medical purposes in ancient Greece and Arabia. In ancient Egypt, it was used to control germs. The first "official" report of sun's medical potential came from Herodotus in the 6th century BC.
He visited an area of the Mediterranean where skulls from a battle were stored and noted a significant difference in thickness between the Egyptian and Persian skulls. While the Egyptian skulls where thick, the Persian skulls were thin and quite fragile. Wunsch said:
"So this is the first idea, or the first report, from the past that there was a connection between sunlight and the robustness of bones in the human system.
Because this was what Herodotus was already reasoning, that the sunlight hardens the bones, the skulls, he thought yes, the Egyptians, they shave their heads, they prayed to the sun [and] they have naked skin.
The Persians, they would wear large hats and protect themselves from the solar irradiation. He was the first, too, to get an idea about things we later learned from vitamin D."
Forms of accepted sun worshipping existed less than 100 years ago, and up until the 1950s sunlight was widely used to treat so-called diseases of darkness: tuberculosis and rickets.
Dr. Niels Finsen was among the first to investigate the effects of sunlight scientifically and, in 1903, he received the Nobel Prize for developing a method to use sunlight to treat the skin manifestation of tuberculosis, known as lupus vulgaris. According to Wunsch:
" … [N]urses — Finsen called them 'light elves' — used concentrated sunlight, which was focused via quartz lenses onto the affected area of the skin using these handles with hollowed chambers, covered on both sides with quartz crystal lens.
The compression of the irradiated skin improved light penetration significantly. The two fittings were used for connecting flexible tubes conducting the cooling water in order to prevent thermal skin burns. This kind of treatment worked perfectly well …"
The only problem was that strong-enough sunlight was only available for a finite number of days in the year in northern latitudes.
He then invented a form of treatment using electrical carbon arc lamps, which promoted the creation of what is now known as phototherapy, or the use of light in the treatment of physical and mental illness.
Heliotherapy: Using Sunlight to Heal
Finsen's work with treating lupus vulgaris using sunlight paved the way for the work of Switzerland's Dr. Auguste Rollier. "This man was to become the master of modern heliotherapy, the sun doctor," Wunsch said, referring to the use of sunlight as a form of therapeutic treatment for disease.
Rollier was successful in treating not just the skin manifestation of tuberculosis, but the systemic manifestation of the disease. He treated patients with sunlight by gradually adapting them to sunlight exposures.
Rollier, who has written textbooks on heliotherapy, emphasizes that the composition of the different parts of the light spectrum are of crucial importance, not only to achieve all of the benefits you can get from the sun, but also to provide protection against potential damage.
For instance, while UVB synthesizes vitamin D in your skin, it can also alter DNA structures, and the ultraviolet A (UVA) rays in sunlight can produce reactive oxygen species in the tissue, leading to damage.
To cope with these side effects, your skin needs other parts in the light spectrum, such as the near-infrared and the red light, which transfer energy to your cells. Wunsch continued:
"Rollier had nearly 50 years of experience with heliotherapy at the end of his medical career. He specifically mentions in his last textbook that he never saw a skin cancer caused by heliotherapy. The opposite is true: he even treated skin cancer with sunlight."
Unlocking the Secret of Vitamin D Synthesis
In 1928, Adolf Windaus was awarded the Nobel Prize for unlocking the secret of vitamin D synthesis.
It was uncovered that UVB light leads to the photosynthesis of vitamin D in the outer layers of the skin, and Windaus developed the first medical preparation of concentrated vitamin D, which is still used today, for example, to fight rickets in children.
Sun lamps were even used for group treatments, including for coal miners. Giving them their daily dose of UVB light helped them to "work harder," Wunsch said. Still, even then most physicians believed that sunlight was superior to artificial light, and this holds true today.
It's not only vitamin D production that makes sun exposure so beneficial but also access to its full spectrum of light. According to Wunsch:
" … [H]istory demonstrates that natural as well as artificial sunlight can act as a major interventional tool to prevent and heal devastating diseases, when used with diligence.
Our ancestors had the skills, knowledge and technologies to deal with the sunlight in all climate regions of our planet, some knowledge, which has vanished in many of the human brains. Before the era of antibiotics, phototherapy was a state-of-the-art treatment in contemporary medicine. Where natural sunlight was unavailable, artificial sunlight was successfully used to fill the gap."
Although our ancestors learned how to treat the most evident disease of darkness using the sun, many people today are still being harmed by a lack of sunlight.
Your Skin Is Made to Be Exposed Gradually to the Sun
All plants and animals know exactly how much sun is good for them, according to Wunsch. "Plants close, or turn away their leaves, until their molecular light harvesting zones. Animals seek the shadow and protect themselves by wearing fur," he says. Human skin is not protected from sunlight by hair, the way many other animals are. Instead, human skin is incredibly complex and has developed new ways to protect itself from solar radiation in the absence of thick hair.
With gradual exposure to sunlight, a mechanism of solar acclimation occurs that prompts a thickening process. " … [T]he main purpose of the thickening is the buildup of a natural sun protection by specifically changing the optical properties of the epidermis," Wunsch explains.
It may take up to four weeks for your skin to build up full protection to your local solar conditions, which means the keratinocytes and corneocyte skin layers are saturated with melanin pigment. In addition, leftover DNA in the keratinocytes in the spinous layer of your skin acts as an additional natural sunscreen.
This DNA is able to transform 99.9 percent of photonic energy from short wavelength photons directly into heat, which means only 0.1 percent is turned into potentially dangerous free radicals. The same is true for melanin. Chemical sunscreens, however, often lead to the creation of free radicals. According to Wunsch:
" … [W]hen you look at the chemical sunscreens, those sunscreens, which have been used 20 years ago, they have a photon conversion rate of just 10 percent, which means 90 percent of the photonic energy will be transformed into oxygen radicals, into free radicals.
And even the latest sunscreens, they have a photon conversion rate of 80 to 81 percent. If you use chemical sunscreens, they will penetrate into your skin and produce additional reactive oxygen species."
How Else Does Sunlight Affect You?
We're only beginning to understand the many ways sun exposure is necessary and conducive to human health. In the video above, you can watch my interview with Wunsch, which explains why the sun is necessary for optimal health. Humans are adapted to sunlight as a complex stimulus that, at the appropriate dosage, helps keep our biological systems running. Wunsch explains:
"Sunlight induces coordinated endocrine adaptation effects. It affects sympathetic and parasympathetic activity, and is a major circadian and seasonal stimulus for the body clock … Our system, via the eyes and via the skin, detects the colors of the light in the environment in order to adapt the hormonal system to the specific needs of the time and place.
It's different if we are sitting under the sun in the desert, or if we are sitting under a leaf roof or under a tree somewhere in the woods. The colors around us tell, through the eye, to our brain, to the mid-brain [and] to the hormonal steering centers, what happens around us and what is to do in order to cope with this particular situation."
Given the many crucial benefits of sun exposure, the WHO's classification as sunlight as a carcinogen (and recommendation to avoid the sun) is akin to saying oxygen may cause cancer because it's the precursor molecule for free radicals, so we should all stop breathing, according to Wunsch.
It's becoming clear that regular exposure to full spectrum light is necessary and beneficial for most people, and public health would be better served by helping people understand the optimal "dose" needed than telling them to shun the sun.
To Learn More, the 100-Year-Old Book 'Light Therapeutics' Is a Relevant Read
If you're interested in learning more, Wunsch recommends the book "Light Therapeutics" by Dr. John Harvey Kellogg, which delves into light's potent power as a therapeutic agent. Though this book refers to light therapy used from 1876 to 1927, Kellogg referred to a time when one day light therapy would be considered for use in every hospital.
Wunsch believes that time is now and humans are ready to once again "see the light," literally and figuratively. He concludes that only fresh air is on the level of sunlight as a prophylactic measure (and sunlight exposure typically goes hand in hand with fresh air), noting:
"The lack of sunlight is probably the dominant factor in cloudy regions in raising the death rate from tuberculosis and degenerative disorder[s] through prevention of normal development and the lowering of vital resistance.
… [T]he interest in light therapy and light as a prophylactic agent has risen to such a high pitch of fervor that the day cannot be far distant when every college and every public school will be supplied with facilities for sun baths, and artificial sunlight supplied by arc lamps will be installed in schools, factories, office buildings, college dormitories, nurseries and in well-furnished hotels and private homes.
A large part of the civilized world is living in the shadow and becoming wan and weazened in consequence. The time has fully come when the whole population should be stirred up to follow the injunction of Holy Writ to 'Walk in the light.' This is from Kellogg, 100 years ago, and I think it's still a contemporary message to all of us."