Exposure to solar ultraviolet radiation limits diet-induced weight gain, increases liver triglycerides and prevents the early signs of cardiovascular disease in mice.

Sunlight exposure is associated with a number of health benefits including protecting us from autoimmunity, cardiovascular disease, obesity and diabetes. Animal studies have confirmed that ultraviolet (UV)-B radiation, independently of vitamin D, can limit diet-induced obesity, metabolic syndrome and atherosclerosis. The aim of this study is to investigate whether exposure to the UV radiation contained in sunlight impacts on these disease parameters.We have trialled an intervention with solar UV in obese and atherosclerosis-prone mice. We have discovered that solar-simulated UV can significantly limit diet-induced obesity and reduce atheroma development in mice fed a diet high in sugar and fat. The optimal regime for this benefit was exposure once a week to solar UV equivalent to approximately 30 min of summer sun. Exposure to this optimal dose of solar UV also led to a significant increase in liver triglycerides which may protect the liver from damage.Our results show that the UV contained in sunlight has the potential to prevent and treat chronic disease at sites distant from irradiated skin. A major health challenge going forward will be to harness the power of the sun safely, without risking an increase in skin cancers.