How are VDR and skin aging related?

The relationship between VDR (vitamin D receptor) and skin aging is supported by mechanistic studies but remains clinically modest. VDR is expressed in keratinocytes and fibroblasts, where it regulates cell proliferation, differentiation, and protection against UV damage. In vitro and animal models indicate that VDR signaling promotes collagen synthesis and reduces oxidative stress. Polymorphisms in the VDR gene (e.g., FokI, BsmI) have been associated with premature skin aging, but effect sizes are small and findings inconsistent. Direct-to-consumer tests often overstate predictive value. Lifestyle factors such as UV exposure, diet, and smoking dominate skin aging. Evidence is best classified as mechanistic with moderate human support. Safety note: Vitamin D supplementation without deficiency may cause harm (e.g., hypercalcemia).