Themed collection The health benefits of UV radiation exposure through vitamin D production or non-vitamin D pathways

Sun exposure stimulates vitamin D production in addition to several immunomodulatory pathways. Fifteen perspectives in this themed issue aim to distinguish the contribution of vitamin D-dependent and independent pathways, initiated by UV radiation exposure, to beneficial health outcomes.

Studies on the determinants of vitamin D status have tended to concentrate on input – exposure to ultraviolet B radiation and the limited sources in food.

Individual components of solar radiation, UVA, UVB and heat generation, are linked to their downstream immune functions, inducing vitamin D production, demonstrating a great degree of overlap between various components.

Focussing on the UV induced cutaneous synthesis of vitamin D, this review gives an update on the relevance of the VDES and of UV radiation for the management of psoriasis and other inflammatory skin diseases.

Asthma is estimated to affect more than 300 million individuals worldwide. Vitamin D is increasingly believed to beneficially influence asthma incidence and control, likely due to effects on innate and adaptive immunity. The primary mechanism for increasing vitamin D in the body is via UVB radiation of skin, however whether UVB has comparable effects to vitamin D on relevant immune mechanisms and asthma is unclear.

UV photoreduces nitrogen oxides sequestered in the skin. The resulting NO moves to the systemic circulation where it vasodilates and lowers BP.

Obesity prevalence is increasing around the world; however, the causes are not known. Here, we discuss moderate sun exposure as a potential modifier of obesity and metabolic dysfunction, with a focus on sun-induced mediators such as vitamin D and nitric oxide.

Women with low sun exposure are at a dose-dependently increased risk of all-cause mortality, mainly due to an increased risk of death from cardiovascular or noncancer/noncardiovascular disease compared higher exposure.

Ultraviolet radiation and vitamin D, with their known immunosuppressive effects, have the potential to delay or inhibit type 1 diabetes.

The earliest record between sun exposure and skin disease goes back five millennia to the ancient Egyptians. Cod liver oil was a folk remedy prior to 1789 and with the observation that sunlight prevented the “appearance of mycelial fungi” in 1877 the modern era commenced with the treatment of cutaneous Mycobacterium tuberculosis.

Acheson et al. (1960) observed an inverse relationship between sunlight exposure and the incidence of Multiple Sclerosis (MS).

The Ultraviolet (UV) radiation contained in sunlight is a powerful mutagen and immune suppressant which partly explains why exposure to solar UV is the biggest risk factor for the development of cutaneous tumours.

Myopia is a major public health concern throughout the world but whether vitamin D played a role in myopia development remains unknown.

Recent equivocal results in high profile randomised controlled trials suggest that the impact of vitamin D deficiency on lung development is complex. In this narrative review we summarise our current understanding of the link between UV exposure, vitamin D and lung development.

Exposure to ultraviolet radiation (UVR) has important and significant consequences on human health.

Vitamin D/UVR effects on T cells that are important in the development of inflammatory bowel disease (IBD).