How are Vitamin D 25-OH and Haut related?

Vitamin D 25-OH (calcidiol) is the primary circulating form used to assess vitamin D status. The skin is both a source (via UVB-induced synthesis) and a target organ. Low 25-OH levels are associated with impaired skin barrier function, psoriasis, and atopic dermatitis. However, evidence is largely mechanistic or observational; high-quality RCTs show modest benefits of supplementation for skin conditions. Additionally, excessive UV exposure increases skin cancer risk. Consumer tests like MyBody-X provide 25-OH measurements, but results must be interpreted in context of lifestyle and sun exposure. The provided context does not contain direct studies on this relationship, so conclusions are based on general knowledge. No specific PMIDs from context.