This review examines the epidemiological evidence that suggests ultraviolet radiation (UVR)
may play a protective role in three autoimmune diseases: multiple sclerosis, insulin-
dependent diabetes mellitus and rheumatoid arthritis. To date, most of the information has
accumulated from population studies that have studied the relationship between geography
or climate and autoimmune disease prevalence. An interesting gradient of increasing
prevalence with increasing latitude has been observed for at least two of the three diseases …