The Influence of Solar-Simulated UV Radiation on Circulating 25(OH)D3, 24,25(OH)2D3 and Their Ratio in Younger and Older Adults
Year: 2025
Type: article
Abstract: Background: In addition to the well-known vitamin D metabolites 25(OH)D and 1,25(OH)2D, the catabolite 24,25(OH)2D may also reflect vitamin D status and influence biological and skeletal processes. However, the effects of UVR-induced synthesis on 24,25(OH)2D levels and the 25-VMR (24,25(OH)2D3:25(OH)D3 ratio) remain unclear. Objectives: We aimed to assess how a single standardised UVR dose influences the production of 25(OH)D3, 24,25(OH)2D3, 1,25(OH)2D3 and 25-VMR, with a comparison between younger and older adults being conducted to explore potential age-related differences in vitamin D metabolism. Methods: A total of 11 young (18–40 years; 7M, 4F) and 10 older (65–89 years; 6M, 4F) skin type I-III volunteers received a single sub-erythemal dose of solar simulated UVR (SSR) (95% UVA: 320–400 nm, 5% UVB: 290–320 nm, 1.3 standard erythemal dose) during winter time in the UK (vitamin D trough season), exposing approximately 35% of the body surface area. The Blood was assayed for 25(OH)D3, 24,25(OH)2D3 and 1,25(OH)2D3 using LC-MS/MS at baseline, 24 h and 7 days following UVR exposure. Results: There was a significant increase in 25(OH)D3 from baseline (44 ± 22 nmoL/L) to 24 h post-UVR (48 ± 22 nmoL/L) in the combined age group (p = 0.044), but no significant differences were found in 24,25(OH)2D3 in the combined group, or between young and older volunteers for both metabolites. 1,25(OH)2D3 concentrations were higher in young groups (163 ± 60 pmoL/L) than in older (105 ± 38 pmoL/L) groups at 7 days post-UVR (p = 0.044). The 25-VMR decreased from baseline (9 ± 3) to 24 h post-UVR (7.5 ± 2.1) in the combined group (p = 0.003). Conclusions: Our data suggest that a single sub-erythemal UVR challenge does not influence 24,25(OH)2D3 concentration in younger and older adults at 24 h and 7 days post-UVR and that the significant difference seen in the 25-VMR between baseline and 24 h post-UVR is due to the increase in 25(OH)D3 concentration post-UVR. This is in line with vitamin D oral supplementation studies, and indicates that low doses of UVR trigger the metabolic pathway, without affecting the catabolic pathway.
Source: Nutrients
DOI: 10.3390/nu17122039
Institutions: Manchester Academic Health Science Centre, University of Manchester, Salford Royal Hospital, Northern Care Alliance NHS Foundation Trust, University of East Anglia, Norwich Research Park, Norfolk and Norwich University Hospital, Norfolk and Norwich University Hospitals NHS Foundation Trust
Language: English
Topic: Vitamin D Research Studies
Subfield: Pathology and Forensic Medicine
Field: Medicine
Domain: Health Sciences
Open Access status: gold
Estimated APC paid: $3,499
Funders: Scottish Government, National Institute for Health and Care Research, British Heart Foundation, China Scholarship Council, National Institutes of Health, Directorate for Biological Sciences, Chief Scientist Office, Scottish Government Health and Social Care Directorate, Manchester Biomedical Research Centre, Engineering and Physical Sciences Research Council, Biotechnology and Biological Sciences Research Council, Centre For Medical Engineering, King’s College London
Awards: G1247657515, G1271318647, G1483213741, G1798610363, G3043027166, EPSRC Centre for Doctoral Training in Smart Medical Imaging at King's College London and Imperial College London, G4835955943, G5386915326, G5454824333, Informing atrial fibrillation rhythm control strategies using electrophysiological testing, cardiac imaging and computational modelling, G7682294364, G9000314647, G961285871
OpenAlex ID: W4411458154