Beneficial health effects of ultraviolet radiation: expert review and conference report.

Carcinogenic effects of ultraviolet radiation (UVR) with reference to skin cancer are the basis of widely implemented recommendations to avoid sun exposure. Whether the benefits of "restrictive sun policies" outweigh their potential harms due to diminished beneficial effects of sunlight exposure remain a matter of controversy. A meeting of experts investigating the beneficial effects of UVR exposure, emphasizing those not mediated by vitamin D, took place in Washington, D.C. on May 27-28, 2024, an excerpt of which is presented here. The aim was to update an inventory of sound scientific data and research on a great variety of implicated health effects. Large cohort studies indicate that various measures of higher sunlight or UVR exposure are associated with improved overall life expectancy. Evidence is accumulating that UVR may prevent and improve various diseases, particularly those related to inflammatory pathologies, though where possible randomized controlled trials (RCTs) are still required to establish causality. Mechanistically, these beneficial effects of UVR extend far beyond vitamin D synthesis in the skin such as the lowering of blood pressure by nitric oxide released from the skin, and activation of neuro-immune-endocrine pathways by a plethora of other mediators at a local and systemic level. In conclusion, the compelling evidence on health benefits of UVR exposure requires serious consideration in public health policies to balance properly the harms and benefits of sunlight exposure and warrants further RCTs to explore the preventive and therapeutic potential of UVR irradiation.