The principal function of vitamin D is to maintain serum calcium and phosphorous levels within the normal levels to support most functions of neurons, muscles, transmission, and bone mineralization.
Low vitamin D levels will precipitate and exacerbate osteoporosis in both men and women and cause the painful bone disease osteomalacia, the milder form that precedes osteoporosis.
Sunlight is hard on skin, and the aging process bares the blame for wrinkles, blemish, and rough, dry skin. But the fact of the matter is that they are both to blame. Photoaging is the process by which skin undergoes changes under the effect of advancing age and due to the harms of the sun. The short UVB wavelengths that cause sunburn can also induce DNA damage DNA and suppress the skin’s immune system. The longer, more penetrating UVA wavelengths may create highly unstable and reactive oxygen molecules (known as oxygen radicals) capable of damaging skin cell membranes and the DNA inside.
The relationship between sun exposure and skin cancer risk is indeed mmultifaceted. Genetic influence is involved, with some protective factors, and other promoting factors. Skin type is another key player: fair skinned people sunburn easily and barely tan are more likely to develop sun-related skin cancer. As for exposure, the “dose” and its timing are crucial. Several studies have suggested that suddenly getting a lot of sun (like laying in the sun from 10 till 6) is more dangerous than steady exposure over time.
There’s also evidence that exposure at a young age is of great importance. A large Scandinavian study of melanoma risk published in the Journal of the National Cancer Institute in 2003 discovered that adolescence is the most critical time to get sunburn. Recent sun exposure didn’t seem to be linked to basal cell carcinoma, the mildest form of skin cancer. Squamous cell carcinoma, a more aggressive form of skin cancer, does not behave the same, however. Cumulative and recent exposure to sunlight at any age is strongly associated with actinic keratoses, scaly growths on the skin that are a risk factor for that type of skin cancer.
It is important to realize that UVB, the DNA-damaging, sunburn-causing wavelengths that sunscreens are intended to block, are also beneficial, as they activate the chemical and metabolic chain reaction that produces vitamin D. Research shows that many a large portion of the population have low vitamin D levels. As already mentioned, there is a well-documented relationship between low vitamin D levels and poor bone health (osteoporosis), and recently, links have been suggested between Vit D and serious diseases like multiple sclerosis and cancer. “Linking” low vitamin D with these diseases is not equivalent to a cause-and-effect equation, but it suggests that possibility. Getting some sun may also shake off the wintertime blues: Research suggests that light hitting your skin, not just your eyes, helps reverse seasonal affective disorder (SAD). Moreover, being outside gets us golfing, gardening, and engaging in other types of physical activity.
The solution is in moderation: using a sunscreen with a sun protection factor (SPF) of at least 15 when you’re outside for an extended period and wearing a hat and shirt around midday, so you can maximize your dermal vitamin D production without incurring substantially more damage to your skin.
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