- Excerpt
"Though we enjoy many beneficial effects of solar radiation, (light and warmth), humans and animals alike are also very sensitive to the harmful effects of one component of the spectrum: ultraviolet light (UVL). Chronic exposure of unprotected skin to UV results in numerous structural and biochemical changes causing premature aging". So wrote researchers Slominski and Pawelek in 1998 in an article published in the scientific journal "Clinics in Dermatology". While their observation that chronic exposure to UV-light is harmful is correct, more emphasis should be put on the fact that the benefits of solar radiation outweigh by far its potentially deleterious effects. As these same authors admit in their article: "Life on earth since inception has depended on a constant source of energy from the burning gasses of our sun," which is "the ultimate source of our sustenance."
Table of contents
What is sunlight ... ?
Yes, what is sunlight ? Obviously, sunlight is light emitted by the sun. But, in terms of physics, what is it? Well, what we call "sunlight" is a part of the totality of solar radiation that comes to us in the form of waves. Just like the waves of oceans, seas, lakes and rivers, the waves of solar radiation have very different lengths. What we call "sunlight" is that part of the solar spectrum that comes in wavelengths that our eyes can absorb and relay to our brain where it is converted to images and colours. The entire spectrum covers very long radio-waves, microwaves, infrared light, visible light that can be broken up in colours (red, orange, yellow, green, cyan, blue and violet), ultraviolet light, x-rays and extremely short gamma-rays. [i] The ensemble of the visible and the invisible ranges adjacent to visible sunlight, respectively to red ‒ IR / infrared or "below red" ‒ and violet ‒ UV / ultraviolet or "beyond violet" ‒, is commonly understood as solar radiation. It makes up 99.9 % of the entire spectrum and consists of approximately 5% UV light, 40% visible light and 55% infrared light. [ii] [iii] Biologically speaking, the invisible infrared and ultraviolet (UV) bands of solar radiation are the most relevant ones. Bear in mind that the "power" of the solar radiation that reaches the surface of the earth depends on the specific location's distance to the sun, the angle at which the radiation is received, the weather (clouds) and the amount of air pollution.
Ultraviolet radiation and vitamin D
The problem with assessing the biological effects of solar radiation is that it harbours very beneficial as well as very harmful components. It is the length of the wave that determines the nature of its biological effect. To complicate this assessment, the sunlight's most harmful component ‒ ultraviolet light ‒ is also of vital importance for our survival due to the fact that our body depends on it to produce vitamin D. So, with UV-blockers having obtained a prominent place in the popular "protect yourself against sunlight" arsenal of creams and lotions, let's take a closer look at this ultraviolet band of solar radiation. In fact, there are 3 types of ultraviolet radiation: UVA, UVB and UVC. Only a fraction of the UVC emitted by the sun reaches the surface of the earth, because most of it is absorbed by the atmosphere. UVB is also absorbed by the atmosphere, but the amount that "gets through" is sufficient to allow the production of vitamin D by the skin. The cells that make up the outer protective layer of the skin (keratinocytes) are uniquely capable of using UVB to produce vitamin D and turn the latter into its active form. For their vitamin D producing activity, the keratinocytes entirely depend on receiving a suffient amount of the UVB component and it is only this particular component that triggers vitamin D production. UVA rays are more abundantly present in sunlight than UVB ones. UVA penetrates more deeply into the skin, but plays no role in vitamin D production.
The good and bad sides of UV
Like so many things in life, UV has its good and its bad side. Although we depend on UVB for the production of the life-sustaining vitamin D by the skin, the bad news is that UVB and UVA are both involved in the generation of skin cancer, photoaging and wrinkle formation. The reason that UV light is harmful stems from the fact that it has an amount of energy that is just sufficient to break chemical bonds, which means that it is capable of unsettling the natural structure of molecules, causing genetic damage and producing destructive free radicals in the outer layers of the skin. Due to its longer wavelength, UVA penetrates more deeply into the skin, which is the reason that especially this A-type of wavelength increases your risk of skin cancer and photoaging. This is also the reason why most dermatologists will advise you to avoid exposure to sunlight or use a UVA&UVB-blocking cream if you can't or won't avoid it. However, the downside of blocking UV radiation is that it will also hamper the production of vitamin D. You may get a wonderful tan, but no vitamin D. So, what to do ?
Sensible exposure to UV is about timing and duration
According to the well-known American doctor and nutritionist Joseph Mercola, to allow your skin to produce vitamin D, "[t]he best time to expose yourself to the sun is as near to solar noon as possible." Note that during Daylight Saving Time - i.e. between the last Sunday of March and the last Sunday of October - solar noon is typically around 13:00! "UVB rays", so Mercola, "unlike UVA rays that are present all throughout the day, are very low in the morning and evening, and are abundant during midday – around 10:00 to 14:00." During Daylight Saving time, this would be around 11:00 and 15:00. "Expose yourself to direct sunlight between these times for a short period, and you will have produced the most vitamin D3. [...] Occasional exposure of your hands and face to the sun does not constitute appropriate sunlight exposure. To optimize your levels, large portions of your skin need to be exposed to the sun. However, over exposure to the sun can result in sunburn, which will increase your risk for skin cancer and premature skin aging. [...] Once you get the proper amount of sunlight, your body will stop producing vitamin D because of its self-regulating mechanism." So, when it comes to exposing your body to UV for the production of vitamin D, Mercola's advice is to avoid UV exposure during the early morning and late afternoon, because during these periods of the day you get more UVA than UVB.
Most importantly: enough is enough !
According to Mercola, "fair-skinned people can potentially max out their vitamin D production in just 10 to 20 minutes, or when their skin has turned the lightest shade of pink. However, if you have darker skin, you likely need to remain in the sun longer. [...] The skin located around your eyes is thinner compared to other areas on your body. Since it has a small surface area, it will not do much to contribute to vitamin D production. You need to protect this part of your face, as it is very prone to photoaging and premature wrinkling. I recommend using a safe sunblock or wearing a cap that will keep your eyes in the shade." [iv] All in all, keep in mind that spending long hours in the sun to get a tan will most likely have harmful effects on your health.
Infrared and near-infrared light "save the day" !
As I just said, dealing with the UV paradox is a complicated affair. Fortunately though, there's more to sunlight than just UV light. In this regard, it's the biologically beneficial infrared and near-infrared band of sunlight that will "save the day"! Bordering the red end of the visible spectrum, we find infrared (IR) and near-infrared (NIR) light. Unless you use infrared "night-vision" goggles, infrared light is invisible. But, it can be experienced as warmth or, when it comes in larger quantities, as heat. In Infrared and skin: Friend or foe, an article published in the Journal of Photochemistry & Photobiology, [v] the authors reported that "it has been known for almost 50 years that low energy exposure to visible and NIR wavelengths is beneficial to humans via the promotion of healing processes. [...] This low level light therapy (so-called LLLT or PBM) provides an alternative therapy for patients needing faster healing of wounds and/or for anti-inflammatory purposes." Today, LLLT/PBM is even used when treating acne and damage caused by UV-exposure, such as actinic keratosis (scaly patches on the skin) and basal cell (benign skin) carcinoma.
Emulating the sun: infrared photoprevention
Apparently, sunlight contains its own "antidote" against the potential dangers of its ultraviolet component: near-infrared light! The authors of Infrared and skin: Friend or foe confirm that, indeed, near-infrared therapy "can also be effective if delivered to normal cells or tissue before the actual insult or trauma, in a pre-conditioning mode. Such application of cutaneous PBM called photoprevention employs visible and, for the most part, IR-A radiation to better prepare the skin for upcoming insults like UV induced sunburn. The process of exposing the skin to such radiation before its exposure to deleterious UVR wavelengths, closely emulates processes found in nature. This is understandable from an evolutionary standpoint since exposure to these early morning red and IR-A wavelengths in sunlight may ready the skin for the coming mid-day deleterious UVR." This protective effect of infrared light was confirmed in a clinical study in which, "prior to exposure to UVB, test subjects were pre-treated with [infrared] light as compared to controls who were not. [...] The results of the study showed a reduction in the UVB-induced erythema [redness] reaction in a significant number of the pre-treated subjects."
Optimizing the sun's photoprevention
The clue to the sunlight "puzzle" is provided by the fact that the ratio of UV to IR is lower in the morning and at the end of the day. In Infrared and skin: Friend or foe the authors suggest that "the Cooler morning temperatures combined with the proportionally lower UV/IR-A ratio provide the ideal conditions to trigger IR-A beneficial effects without skin hyperthermia [over-heating] before potential UV insults (higher UV/IR-A ratio at noon). The same applies late in the afternoon with PBM tissue repair, if UV damage occurs. Consequently, IR-A prevents and restores the possible mid-day UVR damage to the skin within beneficial physiological irradiance boundaries." The authors conclude that the effects of early morning - late afternoon solar radiation exposure might very well be compared with those obtained in low level light therapy. Such natural ‒ non-chronic ‒ light exposure might even pre-condition the skin, preparing it for upcoming (mid-day / solar noon) UVR insults. "One could therefore assume that early morning 'sun salutation' (surya namaskar) and late afternoon procrastination on the beach are actually natural [LLLT-type] treatments to prevent and repair, respectively. Consequently, if your shadow is taller than you are (in the early morning and late afternoon) you're taking advantage of the beneficial effects of IR-A, while avoiding peak (Zenithal) harmful UVR. Ultimately, it is another way of being sun smart.
Adding it all up and don't forget OPCs
While it is true that the ratio of UVA to UVB is higher in early morning and later afternoon sunlight, this comparison fails to take into account the merits of the practice of "sun saluation". All in all, when we "do the math" and add up the negative and positive effects of solar radiation, it's obvious that the combination of early-morning and late-afternoon exposure to the sun combined with a brief exposure during solar noon provides the best way of making use of the "ultimate source of our sustenance": the sun. But, to make sure that we secure the sun's benefits and minimize its harmful effects, we can fall back on nature's own "ultimate source of sustenance": antioxidants. In one of his lectures, professor Jack Masquelier, who invented the use of OPCs as antioxidants, addressed the use vitamins E and C to protect the skin against solar radiation. “Surely,” he said, these vitamins “are antioxidants that play a role in our natural defence system. They do indeed, but only if we eat food that contains enough of them! And we cannot always check the doses of vitaminC and E we consume in a day." [vi] The result is that many people suffer from a chronic excess of free radicals. Masquelier then pointed out that his OPCs not only protect us against free radical damage caused by UV radiation, but also help to maintain the body's "reservoir" of vitamin C. So, combining these two "ultimate sources of sustenance", the sun and OPCs, could very well be the most productive and safest way to reap the benefits and minimize the adverse effects of solar radiation.
[i] Please note that since the late 19th century, Man became not only exposed to the electromagnetic energy-waves that are generated by processes that take place in the sun, but also to those emitted by man-made technological devices. Although the wavelengths may be similar, this article is about energy-waves generated by the sun. It's not about energy waves generated by human devices, such as x-ray machines, 5G antenna's and microwave ovens.
[ii] The Solar Radiation Spectrum
[iii] Infrared and Skin: Friend or Foe; Daniel Barolet, François Christiaens, Michael R. Hamblin; Journal of Photochemistry and Photobiology B Biology; December 2015.
[iv] Dr. Joseph Mercola - Vitamin D Resource Page
[v] See ii supra.
[vi] Dr. Masquelier’s Premier Scientific Addres; Baltimore; 16 October 1996. Published in A Lifetime devoted to OPC and Pycnogenols; Alfa Omega Editrice; Rome; Italy. 1997.