Vitamin D is activated in the skin. This process is initiated by exposure to ultraviolet B (UVB) rays from sunlight. The UVB radiation triggers a series of chemical reactions within the skin, converting a precursor molecule into previtamin D3. This previtamin D3 then undergoes further transformation, ultimately forming the active form of vitamin D. It's crucial to note that excessive sun exposure can be harmful and it's important to obtain vitamin D through a balanced approach that combines sun exposure with dietary intake and supplementation when needed.
Several sources confirm this:
- The most well-known source of vitamin D is via synthesis in the skin induced by sun exposure. (Reference 1)
- Vitamin D production in the skin under the influence of sunlight (UVB) is maximized at levels of sunlight exposure that do not burn the skin. (Reference 2)
- ...it is also produced endogenously when ultraviolet (UV) rays from sunlight strike the skin and trigger vitamin D synthesis. (Reference 3)
- Thermal activation of previtamin D3 in the skin gives rise to multiple non–vitamin D… (Reference 4) This implies the activation process involves more than just simple exposure to sunlight. A thermal aspect is also involved.
While other vitamins like Vitamin C are used topically in skincare products and described as "activated" in marketing materials (References 5, 6, 7, 9, 10), the activation described refers to the formulation or release of the vitamin within the product itself and not to a biological activation process within the skin. These products don't inherently create the vitamin within the skin.
