Pre-Print: Risk–benefit balance of habitual ultraviolet exposure for cardiovascular, cancer, and skin cancer mortality

Cancer Grant, W. B., & Garland, C. F. (2006). The association of solar ultraviolet B (UVB) with reducing risk of cancer: Multifactorial ecologic analysis of geographic variation in age-adjusted cancer mortality rates. Anticancer Research, 26(4A), 2687–2699. Breast Cancer Mohr, S. B., Garland, C. F., Gorham, E. D., Grant, W. B., & Garland, F. C. (2008). Relationship between low ultraviolet B irradiance and higher breast cancer risk in 107 countries. The Breast Journal, 14(3), 255–260. https://doi.org/10.1111/j.1524-4741.2008.00576.x Diabetes Mohr, S. B., Garland, C. F., Gorham, E. D., & Garland, F. C. (2008). The association between ultraviolet B irradiance, vitamin D status, and incidence rates of type 1 diabetes in 51 regions worldwide. Diabetologia, 51, 1391–1398. https://doi.org/10.1007/s00125-008-1061-5 Multiple Sclerosis Hedström, A. K., Olsson, T., Kockum, I., Hillert, J., & Alfredsson, L. (2020). Low sun exposure increases multiple sclerosis risk both directly and indirectly. Journal of Neurology, 267, 1045–1052. https://doi.org/10.1007/s00415-019-09695-2 Stroke Kent, S. T., McClure, L. A., Judd, S. E., Howard, V. J., Crosson, W. L., Al-Hamdan, M. Z., & Kabagambe, E. K. (2013). Short- and long-term sunlight radiation and stroke incidence. Annals of Neurology, 73(1), 32–37. https://doi.org/10.1002/ana.23738 Depression Wang, J., Wei, Z., Yao, N., Li, C., & Sun, L. (2023). Association between sunlight exposure and mental health: Evidence from a special population without sunlight in work. Risk Management and Healthcare Policy, 16, 1049–1057. https://doi.org/10.2147/RMHP.S401311 Alzheimer’s / Dementia Ma, L. Z., Ma, Y. H., Ou, Y. N., Chen, S. D., Yang, L., Dong, Q., Cheng, W., Tan, L., & Yu, J. T. (2022). Time spent in outdoor light is associated with the risk of dementia: A prospective cohort study of 362,094 participants. BMC Medicine, 20(1), 132. https://doi.org/10.1186/s12916-022-02317-7 Obesity / Metabolic Health Muldowney, S., Lucey, A. J., Paschos, G., Martinez, J. A., Bandarra, N., Thorsdottir, I., & Kiely, M. (2011). Relationships between vitamin D status and cardio-metabolic risk factors in young European adults. Annals of Nutrition and Metabolism, 58(2), 85–93. https://doi.org/10.1159/000323999 Osteoporosis Odén, A., Kanis, J. A., McCloskey, E. V., & Johansson, H. (2014). The effect of latitude on the risk and seasonal variation in hip fracture in Sweden. Journal of Bone and Mineral Research, 29(10), 2217–2223. https://doi.org/10.1002/jbmr.2254 WHO / Sunlight Report Mead, M. N. (2008). Benefits of sunlight: A bright spot for human health. Environmental Health Perspectives, 116(4), A160–A167. https://doi.org/10.1289/ehp.116-a160

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.

A 2019 clinical pilot study published in Frontiers in Microbiology examined whether skin exposure to narrowband UVB light could influence the human gut microbiome. In healthy adults, three controlled UVB exposures over one week increased serum vitamin D levels and led to measurable changes in gut microbiota composition, particularly in participants who were vitamin D insufficient at baseline. Researchers observed increased microbial diversity and enrichment of bacterial families commonly associated with gut health, supporting the existence of a skin–gut axis through which UVB light exposure may influence intestinal homeostasis. These findings suggest that targeted UVB exposure can have systemic biological effects beyond the skin, potentially linking light exposure, vitamin D status, and microbiome health.