A common nutritional disease of past centuries, caused by vitamin D deficiency was rickets, which resulted both from a deficient diet and from lack of sunlight.
I was a vegetarian until I started
leaning toward the sunlight (R. Rudner)
In 17th-century England rickets was so prevalent as to pass for a normal state. Like most English children, young Charles I suffered from it, but his physician merely reported that the "joynts of his knees, hips and ankles, being great and loose, are not yet closed and knit together as it happeneth to many in their tender years". Rickets produces a softening of the bones, which then bend under the body's weight, causing bow-legs or knock-knees. In adults a related disease, osteomalacia, produces much pain, particularly in the spine or pelvis, as well as chronic fatigue.
Vitamin D history
In rickets as in scurvy (caused by vitamin C deficiency), practical experience pointed to cures long before vitamins were discovered and medical science could explain why they worked. In the 19th century cod-liver oil (containing vitamin D) was used as both cure and preventive, to the disgust of generations of children who were forced to swallow it every day. The explanation came in 1919, when Sir Edward Mellanby proved the existence of an agent in cod-liver oil which was finally isolated and produced in 1931 as pure vitamin D. This vitamin D, which increases the amount of calcium and phosphate deposited in the bones, may be found not only in fish oils but also in eggs, and in small quantities in butter and milk. Vitamin D is also manufactured by the body when the sun's ultra-violet rays strike the skin. This is why in tropical areas rickets and osteomalacia are virtually unknown regardless of diet, afflicting only certain Moslem women and others who keep out of the sun.