this vitamin may be synthesized as a result of sunlight exposure
Vitamin D
title: Cholecalciferol text: in the opening of the vitamin precursor B-ring through a conrotatory pathway making previtamin D3 (pre-cholecalciferol). In a process which is independent of UV light, the pre-cholecalciferol then undergoes a [1,7] antarafacial sigmatropic rearrangement and therein finally isomerizes to form vitamin D. The active UVB wavelengths are present in sunlight, and sufficient amounts of cholecalciferol can be produced with moderate exposure of the skin, depending on the strength of the sun. Time of day, season, and altitude affect the strength of the sun, and pollution, cloud cover or glass all reduce the amount of UVB exposure. Exposure of face, arms title: Health effects of sunlight exposure text: benefits, and a number of public health organizations state that there needs to be a balance between the risks of having too much sunlight or too little. There is a general consensus that sunburn should always be avoided. UVB radiation with a wavelength of 290–315 nanometers penetrates uncovered skin and converts cutaneous 7-dehydrocholesterol to previtamin D, which in turn becomes vitamin D. UVB radiation does not penetrate glass, so exposure to sunshine indoors through a window does not produce vitamin D. Time of day, time of year, geographic latitude, ground altitude, cloud cover, smog, skin melanin content, and sunscreen are title: Health effects of sunlight exposure text: Health effects of sunlight exposure The ultraviolet radiation in sunlight has both positive and negative health effects, as it is both a principal source of vitamin D and a mutagen. A dietary supplement can supply vitamin D without this mutagenic effect. Vitamin D has a wide range of positive health effects, which include strengthening bones and possibly inhibiting the growth of some cancers. UV exposure also has positive effects for endorphin levels, and possibly for protection against multiple sclerosis. Visible sunlight to the eyes gives health benefits through its association with the timing of melatonin synthesis, maintenance of normal and title: Health effects of sunlight exposure text: a time when large populations have migrated far from the climates for which their skin was genetically adapted. Health effects of sunlight exposure The ultraviolet radiation in sunlight has both positive and negative health effects, as it is both a principal source of vitamin D and a mutagen. A dietary supplement can supply vitamin D without this mutagenic effect. Vitamin D has a wide range of positive health effects, which include strengthening bones and possibly inhibiting the growth of some cancers. UV exposure also has positive effects for endorphin levels, and possibly for protection against multiple sclerosis. Visible sunlight to title: Light skin text: every part of the human body, including the skeleton, the immune system, and brain requires vitamin D. Sunlight is necessary for the production of vitamin D. Vitamin D production in the skin begins when UV radiation penetrates the skin and interacts with a cholesterol-like molecule produce pre-vitamin D3. This reaction only occurs in the presence of medium length UVR, UVB. Most of the UVB and UVC rays are destroyed or reflected by ozone, oxygen, and dust in the atmosphere. UVB reaches the Earth’s surface in the highest amounts when its path is straight and goes through a little layer of