Narrowband ultraviolet B three times per week is more effective in treating vitamin D deficiency than 1600 IU oral vitamin D₃ per day: a randomized clinical trial

This mouse study tested whether Solius UVB light therapy could influence gut health, comparing vitamin D sufficient and deficient mice given either a single exposure or six repeated exposures over 14 days. Repeated exposures significantly increased vitamin D levels to match sufficient-diet controls without injury to the skin. Notably, repeated therapy significantly altered gut microbiota composition and fecal metabolome, especially in vitamin D–deficient mice, enriching bacteria linked to metabolic health and leanness while increasing beneficial compounds like short-chain fatty acids, bile acid derivatives, and tryptophan metabolites. Pathway analysis further suggested UVB exposure inhibited oxidative stress and tumor-related signaling while activating anti-inflammatory pathways. Serum metabolomic changes were much smaller than fecal changes, suggesting the effects were concentrated in the gut rather than just reflecting systemic responses. Overall, the study concludes Solius UVB therapy can be safely used to reshape gut microbial and metabolic profiles in a way that promotes gut health.

Populations in lower-sun latitudes show higher rates of multiple chronic diseases, largely attributed to reduced UVB-driven vitamin D synthesis and other non-vitamin-D biological pathways.

This randomized, placebo-controlled, clinical trial showed that the SOLIUS system effectively increased 25(OH)D concentrations in individuals with vitamin D deficiency or insufficiency, offering a safe solution for improving vitamin D status. The treatment group showed a significant increase in serum 25(OH)D concentrations, with an average increase of 10.2 ng/ml (p<0.01), compared to a decrease of 2.3 ng/ml in the control group.