History
Greek physician Soranus of Ephesus, one of the chief representatives of the Methodic school of medicine who practiced in Alexandria and subsequently in Rome, reported deformation of the bones in infants as early as the first and second centuries AD. Rickets was not defined as a specific medical condition until 1645, when an English physician Daniel Whistler gave the earliest known description of the disease. In 1650 a treatise on rickets was published by Francis Glisson, a physician at Caius College, Cambridge, who said it had first appeared about 30 years previously in the counties of Dorset and Somerset. In 1857, John Snow suggested rickets, then widespread in Britain, was being caused by the adulteration of bakers bread with alum. German pediatrician Kurt Huldschinsky successfully demonstrated in the winter of 1918–1919 how rickets could be treated with ultraviolet lamps. The role of diet in the development of rickets was determined by Edward Mellanby between 1918 and 1920. In 1923, American physician Harry Steenbock demonstrated that irradiation by ultraviolet light increased the vitamin D content of foods and other organic materials. Steenbocks irradiation technique was used for foodstuffs, but most memorably for milk. By 1945, rickets had all but been eliminated in the United States. Etymology
The word rickets may be from the Old English word wrickken (to twist), although because this is conjectured, several major dictionaries simply say "origin unknown". The name rickets is plural in form but usually singular in construction.
Conversely, latitudes near the equator have selection for darker skin that can block the majority of UV radiation to protect from toxic levels of vitamin D, as well as skin cancer.An anecdote often cited to support this hypothesis is that Arctic populations whose skin is relatively darker for their latitude, such as the Inuit, have a diet that is historically rich in vitamin D. Since these people acquire vitamin D through their diet, there is not a positive selective force to synthesize vitamin D from sunlight.Environment mismatch: vitamin D deficiency arises from a mismatch between an individuals previous and current environment. This risk of mismatch increases with advances in transportation methods and increases in urban population size at high latitudes.Similar to the environmental mismatch when dark-skinned people live at high latitudes, Rickets can also occur in religious communities that require long garments with hoods and veils. These hoods and veils act as sunlight barriers that prevent individuals from synthesizing vitamin D naturally from the sun.In a study by Mithal et al., vitamin D insufficiency of various countries was measured by lower 25-hydroxyvitamin D. 25(OH) D is an indicator of vitamin D insufficiency that can be easily measured. These percentages should be regarded as relative vitamin D levels, and not as predicting evidence for development of rickets. Asian immigrants living in Europe have an increased risk for vitamin D deficiency. Vitamin D insufficiency was found in 40% of non-Western immigrants in the Netherlands, and in more than 80% of Turkish and Moroccan immigrants.