Vitamin D3 (cholecalciferol) is a fat-soluble vitamin. It can be synthesized by the skin under UVB rays or obtained through diet and supplementation. Modern lifestyles and sun protection can limit its natural skin synthesis, making supplementation often necessary.
Authorized health claim (EU Regulation 432/2012): vitamin D contributes to the normal functioning of the immune system. This claim is authorized when the daily intake provides at least 15% of the NRV.
In scientific literature, vitamin D3 is documented for its role in bone metabolism (calcium fixation and distribution), cell differentiation, and immune function regulation. These roles are well documented scientifically and widely published.
At the skin level, vitamin D3 is documented for its role in keratinocyte differentiation, the main cells of the epidermis. This property is associated in literature with maintaining skin function.
