How are Vitamin D 25-OH and skin aging related?

The relationship between vitamin D (25-OH) and skin aging is not clearly established by evidence. Vitamin D is synthesized in the skin upon UV exposure and is involved in cell proliferation, inflammation regulation, and DNA repair – processes relevant to skin aging. Some observational studies suggest an association between low vitamin D levels and increased wrinkling or loss of elasticity, but interventional trials showing that supplementation slows skin aging are lacking. Moreover, higher vitamin D levels may simply reflect greater sun exposure, which itself accelerates photoaging. Therefore, measuring 25-OH alone is insufficient to assess skin aging risk. The evidence is primarily mechanistic and observational. Any supplementation decisions should be made with a healthcare provider, considering overall health and sun exposure habits.