About the book In In Defense of Sunlight, science journalist Rowan Jacobson makes the case that the public health conversation around sun exposure has been incomplete. Yes, too much sun carries real risks. But avoiding it entirely comes at a biological cost that most people don't fully appreciate. Drawing on decades of research, Jacobson explores how UVB light does far more than produce vitamin D - driving hormone production, supporting the microbiome, releasing nitric oxide, and influencing mood, immunity, and cardiovascular health through pathways that oral supplements simply can't replicate. The book features a foreword by Dr. Richard Weller, a leading dermatologist and researcher whose work on nitric oxide and sunlight helped reshape how scientists think about UV exposure and human health. Where the science leads Solius was built around the same body of research Jacobson explores in the book. People are increasingly caught between two competing realities. On one hand, the scientific evidence continues to show that sunlight plays an important role in human health. On the other, excessive sun exposure carries well-established risks, including skin damage and skin cancer. For decades, the conversation has largely been framed as a choice between getting the benefits of sunlight and avoiding its risks. Solius was designed to solve that dilemma. By delivering a personalized dose of targeted UVB light, it provides a way to access the biological benefits associated with sunlight while dramatically reducing unnecessary UV exposure. The challenge has always been dosing. The right amount of UVB is different for every person. Skin tone, age, geography, season, weather, and prior sun exposure all influence how much UVB someone should receive. Too little may provide little benefit, while too much can increase risk. Solius solves that problem by automatically measuring the user, calculating a personalized dose, and delivering it consistently in just a few minutes each week. About the author Rowan Jacobsen writes about science and nature and the less-explored corners of the world for Harper’s, Outside, The Atlantic, Scientific American, Smithsonian, The New York Times, The Washington Post, MIT Technology Review, Businessweek, and others, and his work has been anthologized in The Best American Science & Nature Writing and other collections. He has received awards from the James Beard Foundation, the Society of American Travel Writers, and the Overseas Press Club. He is the author of nine books, including A Geography of Oysters, Fruitless Fall, and Truffle Hound, several of which have been named to Best Book of the Year lists by The Washington Post, The Wall Street Journal, The Boston Globe, NPR, and Publishers Weekly. He has performed with Pop-Up Magazine, lectured at Harvard and Yale, and appeared on CBS, NBC, and NPR. He has been an Alicia Patterson Foundation Fellow, writing about endangered diversity on the borderlands between India, Myanmar, and China; a Knight Science Journalism Fellow at MIT, focusing on the environmental and evolutionary impact of synthetic biology; and a Nova Media Fellow, researching the science of sun exposure.
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"Solius: The first to bring to market a next-generation, over-the-counter FDA-cleared light for raising Vitamin D levels."
Endocrinology
Related Studies
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Higher disease rates in low sun latitudes
Multiple Articles
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
Featured Research
Higher disease rates in low sun latitudes
Multiple Articles
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
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Effectiveness of SOLIUS UVB Light System in Enhancing Serum 25-Hydroxyvitamin D Concentrations: A Randomized Controlled Trial
Anticancer Research
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.
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Effectiveness of SOLIUS UVB Light System in Enhancing Serum 25-Hydroxyvitamin D Concentrations: A Randomized Controlled Trial
Anticancer Research
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.
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Skin Exposure to Narrow Band Ultraviolet (UVB) Light Modulates the Human Intestinal Microbiome
Frontiers in Microbiology
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.
Featured Research
Skin Exposure to Narrow Band Ultraviolet (UVB) Light Modulates the Human Intestinal Microbiome
Frontiers in Microbiology
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.