Hypothesis--ultraviolet-B irradiance and vitamin D reduce the risk of viral infections and thus their sequelae, including autoimmune diseases and some cancers.

摘要: Many viral infections reach clinical significance in winter, when it is cold, relative humidity lowest and vitamin D production from solar ultraviolet-B irradiation at its nadir. Several autoimmune diseases, such as multiple sclerosis, type 1 diabetes mellitus asthma, are linked to infections. Vitamin D, through induction of cathelicidin, which effectively combats both bacterial infections, may reduce the risk several diseases cancers by reducing development Some types cancer also The with seemingly important based on correlations increasing latitude United States, an index wintertime dose bladder, prostate, testicular thyroid cancer, Hodgkin's non-Hodgkin's lymphoma, and, perhaps, gastric cancer. evidence examined includes role viruses etiology these geographic seasonal variation time life effective disease. In general, supports hypothesis. However, further work required evaluate this