What is UV and where does it come from?
The Sun is a fiery orb with a mass 330,000 times bigger than the Earth, and it generates energy by a nuclear fusion of hydrogen into helium. A small portion of that energy then reaches the Earth in the form of Sunlight, warming our planet and giving us energy. In fact, all life on Earth is dependent on the power of the Sun transmitted by Sunlight, which is only half visible.
Part of that Sunlight is known as Ultraviolet Light (UV), which is invisible because its wavelength is shorter than the violet part of the sunlight specter. There are 3 main varieties of UV: UVA, UVB and UVC; but we are most interested in UVB which stimulates the production of Vitamin D when it contacts the skin.
90% percent of all vitamin D in human beings is produced by sunlight exposure, and approximately 105 diseases have a correlation to a deficiency of vitamin D!
How the lack of Sunlight is affecting the Elderly
A recent published paper by dermatologist Dr. Richard Weller and his colleague Dr. Wright, helps to dispel many myths about sunlight exposure. They actually promote sunlight for older people and make several important points. These are the highlights:
“Intermittent sun exposure is a risk factor for the more dangerous melanoma but chronic sun exposure and outdoor occupation may be protective.”
“Public health advice has tended to concentrate on the dangers of sun exposure despite the absence of any data that increased sun exposure correlates with raised all-cause mortality.”
“Inadequate sun exposure carries its own risks, and the older population are particularly sun deprived as recorded by low serum Vitamin D levels and lack of outdoor activity.”
“Sunlight has health benefits dependently and independently of vitamin D synthesis. Low serum vitamin D levels correlate with increased morbidity and mortality but the direction of association is not always clear. Vitamin D has a causal role in calcium and phosphate metabolism, in skeletal health and probably reduction of colorectal cancer.”
“…..mobilization of nitric oxide by UVA radiation from nitrate stores in skin, with consequent reduction in BP, may account for the observed reduction in cardiovascular disease and all-cause mortality with increased sun exposure.”
“Advice on healthy sun exposure needs to be reconsidered, with reduction in all-cause mortality and morbidity as the primary end point.”
As the article concludes, older adults should adopt a balanced approach to sun exposure. Behavioural recommendations should be tailored to race/skin type and geographical location given the variation in UVR with latitude. Public health recommendations may evolve to warn of the dangers of inadequate or insufficient UV exposure in addition to excessive exposure.
Sun exposure can have harmful effects. Sun avoidance, common in the elderly, is undoubtedly harmful. A balance must be met. More dedicated research in the elderly is required.