IRR Group Leader Prof Richard Weller and other leading experts convened in Washington, D.C. to share and discuss the latest research on the health benefits of sun exposure - beyond vitamin D. Researchers summarise key findings, ongoing questions, and future research directions in a recent paper. Sunlight has long been seen as both essential for life and harmful. While ultraviolet radiation (UVR) from the sun is known to cause skin cancer, it also provides important health benefits. For much of the 20th century, public health advice has focused on minimising sun exposure due to UVR’s cancer risk. However, this 'no sun' approach may overlook positive effects of sunlight.Early studies showed that UVR might improve health, but these findings have largely been ignored after UVR was recognised as a carcinogen in 1928 and later classified as a 'Group 1 human carcinogen' by IARC (cancer agency of the World Health Organization) in 2006. Newer research shows that UVR may do more than help the skin produce vitamin D - it can also positively influence the body’s immune, hormonal, and nervous systems. My lab looks at the mechanisms by which sunlight exerts its health benefits. We know vitamin D only accounts for a tiny proportion of the benefits of sunlight and taking vitamin D tablets does not make up for the lack of sunlight. As current public health advice overlooks the significant health benefits of sunlight, we strongly feel this existing advice needs reconsidering. Professor Richard Weller IRR Group Leader and paper's author Heart, immunity and brain benefitsStudies show that regular sun exposure is linked to lower risk of death from causes such as heart disease, cancer and diabetes. In fact, low sun exposure has been associated with a risk of death similar to smoking, prompting experts to question current sun avoidance guidelines, especially in low-light regions like Scandinavia and the UK.Regular sun exposure can lower blood pressure and reduce risks of heart disease, type 2 diabetes, and obesity. These effects are likely driven by sunlight-triggered release of nitric oxide in the skin, rather than just vitamin D, with studies showing improvements in regulating weight and insulin sensitivity.UVR also appears to benefit the immune system by reducing inflammation and potentially lowering the risk or severity of diseases such as multiple sclerosis (MS), childhood eczema, COVID-19, and other autoimmune conditions. These effects are thought to stem from UVR's ability to influence immune cell activity, vitamin D levels, and even the skin and gut microbiomes.A large Scottish study found that higher exposure to sunlight, especially UVB radiation, during pregnancy was linked to a lower risk of learning disabilities in children - likely due to vitamin D's vital role in brain development. Separately, UVB light was shown to affect metabolism, sexual behaviour and reproductive health, with notable differences between males and females, offering potential for targeted therapies.Cancer and skin pigmentationWhile sunburn and tanning beds are shown to increase melanoma risk, broad sunlight avoidance hasn’t been shown to reduce melanoma deaths. Additionally, higher exposure to ambient UVB radiation has been associated with lower risks of oesophageal and gastric cancers. People with darker skin (with higher melanin levels) tend to produce less vitamin D from sunlight due to melanin’s natural UV-blocking effect. Encouraging safe sun exposure in people with dark skin, could benefit from safe sun exposure without high skin cancer risk.Sunlight has wide-reaching health benefits beyond vitamin D, including impacts on immunity, blood pressure, and brain development. As evidence grows, experts urge reconsideration of public health advice to reflect a more balanced approach to sun exposure. The Washington, D.C. meeting was supported by the Sunshine Health Foundation (SHF).Read the full paper in Photochemical & Photobiological SciencesWeller research group Tags CIR Publication date 19 Jun, 2025
