Summer sunshine makes most of us feel better, but there may be more to its benefits than just feeling good. A growing body of evidence suggests sunlight itself – with adequate protection, of course – may actually be good for health.
Sunlight comprises two types of solar radiation: UVA, which causes reddening and burning of the skin, and UVB. The latter increases the production of an inactive form or precursor of vitamin D by the skin, which is then activated by the liver and kidneys.
Unfortunately, both UVA and UVB also increase the risk of skin cancer, including the most deadly type, melanoma, which is why you should always take a balanced approach to sunlight exposure.
Only a few foods, such as fatty fish and mushrooms, contain vitamin D, so we get most of it from sunlight. This means not enough sun exposure, or pigmentation of the skin (which diminishes the production of vitamin D precursors), often results in low vitamin D levels.
Vitamin D deficiency is associated with many signs of ill healthand diseases. These include low bone density and broken bones due to osteoporosis, muscle weakness, diabetes, multiple sclerosis, cardiovascular disease, colon cancer and an overall increased risk of dying prematurely. But studies of supplementation with this vitamin have not always shown beneficial effects on treating these conditions.
This raises an important question about the actual source of vitamin D deficiency: could low vitamin D levels actually result from an unidentified underlying disease process (such as inflammation) leading to ill health? In other words, could low vitamin D levels be the symptom rather than the cause of illness?
source: the conversation