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Theme 3: Project 3 - UV radiation - effects on vitamin D sufficiency and blood pressure
Vitamin D deficiency/insufficiency is a worldwide health problem that is associated not only with impaired musculoskeletal health, but also a wide range of acute and chronic immune-mediated diseases ranging from autoimmune and allergic conditions to cancer. However, much of the evidence is ecologic, often using surrogates for vitamin D status, such as latitude. In general supplementation studies have not supported the epidemiology.
One explanation is that vitamin D obtained naturally via solar UVR may have biological advantages, perhaps in combination with other UVR effects. A direct comparison of the biological effects of vitamin D obtained by UVR versus supplementation has never been made. UVR and vitamin D have effects on immune function so an assessment of immunological endpoints would be an ideal way to assess differences.
The optimal way to restore serum 25-hydroxyvitamin D sufficiency is currently debatable. UV irradiation through sunshine exposure promotes endogenous vitamin D synthesis, although this can also be associated with a risk of UV-induced skin cancer. Alternatively dietary supplements represent an alternative, which are increasingly being used in clinical trials to correct deficiency.
However it is unclear whether sunshine exposure and vitamin D supplementation induce comparable changes in immune function, or whether additional UV-induced molecules may be responsible for proposed health benefits.