7-dehydrocholesterol

provitamin

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Last updated

June 25, 2026

Quick Summary

7-dehydrocholesterol is a crystalline steroid alcohol found in higher animals and humans, primarily in the skin. It is synthesized from cholesterol and is also known as dehydrocholesterol.1

When exposed to ultraviolet light, 7-dehydrocholesterol converts into vitamin D₃, also known as cholecalciferol. Vitamin D₃ is a natural form of vitamin D that can be found in sources like fish and egg yolks. This conversion process in the skin is how the body produces vitamin D when exposed to sunlight.12

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Adolf Windaus
Windaus discovered 7-dehydrocholesterol, which is the chemical precursor of vitamin D, and he showed that it is a steroid. He discovered that it is converted into the vitamin when one of its chemical bonds is broken by the action of sunlight. This explained why exposure to sunlight…
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Windaus discovered 7-dehydrocholesterol, which is the chemical precursor of vitamin D, and he showed that it is a steroid. He discovered that it is converted into the vitamin when one of its chemical bonds is broken by the action of sunlight. This explained why exposure to sunlight…
Read More

photochemical reaction
Photorearrangement
…reaction is the conversion of 7-dehydrocholesterol to vitamin D in the skin. Lack of exposure to solar radiation can cause a deficiency of vitamin D, which leads to a debilitating decalcification of the bones called rickets. This disorder was first described by Roman physicians in the 2nd
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…reaction is the conversion of 7-dehydrocholesterol to vitamin D in the skin. Lack of exposure to solar radiation can cause a deficiency of vitamin D, which leads to a debilitating decalcification of the bones called rickets. This disorder was first described by Roman physicians in the 2nd
Read More

vitamin
Vitamin D group
…other animals the provitamin (7-dehydrocholesterol), which is found in skin, can be converted by sunlight to vitamin D₃ and thus is an important source of the vitamin. Both vitamin D₂ and vitamin D₃ can be utilized by rats and humans; however, chicks cannot use vitamin D₂ effectively. The form…
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…other animals the provitamin (7-dehydrocholesterol), which is found in skin, can be converted by sunlight to vitamin D₃ and thus is an important source of the vitamin. Both vitamin D₂ and vitamin D₃ can be utilized by rats and humans; however, chicks cannot use vitamin D₂ effectively. The form…
Read More