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What Vitamin Is Made in the Skin?

Vitamin D, specifically D3, is the sole vitamin produced in the epidermal layer of the skin. Its production from 7-dehydrocholesterol utilizes sun rays; therefore adequate sun exposure is necessary to meet our body's requirement for vitamin D. Vitamin D is instrumental in the maintenance of body health.

  1. Vitamin D Basics

    • Vitamin D has several functions in the body. First, it aids in the general absorption of calcium. Without vitamin D, calcium cannot be absorbed, which makes it necessary in the growth and maintenance of healthy bones. Vitamin D is also important "modulation of neuromuscular and immune function and reduction of inflammation." Lastly, genes encoding proteins, which control the growth of cells as well as cell differentiation, use vitamin D.

    Production

    • Vitamin D3 production occurs in the skin. Its conversion is from 7-dehydrocholestorol, which is produced by the body. 7-dehydrocholesterol converts to pre-vitamin D3 via sun exposure, and then finally to vitamin D3. UVB rays between 295 and 300 nm converts 7-dehydrocholesterol the best. Because 7-dehydrocholesterol is mostly in the outside layer of the skin (the epidermis), most of its conversion occurs in these layers. Therefore vitamin D3 production occurs primarily in the epidermis.

    Recommendations

    • Recommendations for the amount of sun exposure for vitamin D production vary by reference. The negative effects of the sun, such as little things like wrinkles to significant illnesses like cancer, have many at odds with how much sun one can receive safely. However, according to the Office of Dietary Supplements, you should have between 5 and 30 minutes of sun exposure without sunscreen twice a week.

    Melanin

    • Because melanin (the component that gives skin its color) acts like a natural sunscreen, it factors into vitamin D production. Sunscreens generally decrease the absorption of UVB rays, which decrease production of vitamin D. Darker skinned people, those with more melanin, therefore require more time in the sun to ensure that 7-dehydrocholesterol receives enough UVB rays for its conversion.

    Other Considerations

    • The amount of sun exposure for vitamin D production varies depends on more than the amount of melanin that you have, though that is a significant factor. Another variable is the weather. Cloudiness due to pollution or general weather significantly reduces the amount of sun that your skin absorbs. Also, your geographic location and the time of day influences how much your skin absorbs. If you are in a dark season or the sun's rays hit your area at angle, you get less sun, and less vitamin D3 production.

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