Humans are hybrids that run on nutrition and solar power. The presence of 7-dehydrocholesterol in the skin enables humans to manufacture vitamin D3 from the sun’s ultraviolet rays. Hence, the positive effect of sunlight is usually just narrowed down to this. But there is more to sunlight than just a vitamin D boost. Sunlight improves blood circulation and protects against depression and insomnia. Track and field coaches all know the difference between indoor training supplemented with vitamin D and outdoor training in the sun. Athletes from colder countries consistently train in warmer countries during the winter. Obviously, they all believe that turning up the heat in the indoor training facility and consuming fatty, vitamin D rich fish does not yield the same result as actual sunlight. Breathing the recirculated air doesn’t help either. But on the rare sunny winter day, should we position ourselves next to the window in hopes of getting the benefits of the sunlight?
Normal glass blocks all ultraviolet B (UVB) but allows ultraviolet A (UVA), which has a longer wavelength, to come through the office windows. Vitamin D formation happens only from UVB rays—so much for our corner office in the glass skyscraper. UVA is used in most tanning beds, as it colors the skin most effectively. But UVA also increases oxidative stress, destroys vitamin D, and increases the risk for skin cancer. Ironically, most people avoid sunlight in fear of skin cancer while the produced vitamin D is proven to fight cancer…
What if we book a vacation trip in the middle of the gray winter? UVB rays will reach us only when the sun is above an angle of 50 degrees from the horizon. This occurs in the middle of the day in the summer, but not in the winter. Even in Florida your body will not produce any vitamin D from sunlight during December and January. If you fly there in February, there’s no rush to sunbathe. By gradually increasing the exposure to sunlight, you allow your body’s melanocyte cells to produce protective pigmentation.
Side tip: Gradual exposure should also be taken into consideration if you use the controversial tanning beds in the winter. The high-pressure sunlamps emit doses of UVA as much as 12 times that of the sun. If you go to a tanning salon in the middle of winter, it will be a shock to your skin.
If you are forced to stay in the sunlight for more than 30 minutes, then of course you should wear sunscreen. Regular sunscreen tends to only block UVB rays, while the so-called “broad-spectrum” sunscreen will also block the UVA rays. The antioxidant astaxanthin appears to have a rejuvenating effect on the skin and could be used by anyone concerned about wrinkles and sunspots. Astaxanthin can be found in salmon and shrimp. (Interestingly, astaxanthin is also used as a food dye and is often added to salmon to give it more color.)
All in all, an outdoor training session during lunch every other day will provide sufficient sunlight during the summer. Supplement with vitamin D during the months when your skin is pale. A simple blood test will reveal if you are deficient.
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