rickets
Rickets is a disease that causes deformity of bones, especially the bones of the spine, ribs, and legs. The disease can result in knock knees, bow legs, pigeon breast, painful spasms, convulsions, and difficulty breathing. Rickets was common in Europe and North America until the early 1900s. Ancient Chinese, Egyptian, Greek, and Roman physicians knew of the disease.
The major cause of rickets is a lack of Vitamin D.
Some of the other causes of rickets include: deficiency of calcium.
British doctor Edward Mellanby attempted to discover if vitamin deficiency was the cause of rickets by feeding laboratory dogs a diet that consisted of only oatmeal and keeping the dogs indoors (out of the sun). The dogs developed rickets. Mellanby then fed the dogs cod liver oil and cured the rickets. Mellanby wrongly concluded that a deficiency of vitamin A caused rickets.
American researcher McCollum, co-discoverer of vitamin A, repeated the experiment, but fed the dogs cod liver oil that had been treated to destroy the vitamin A content. The modified cod liver oil still cured the dogs, so McCollum concluded that it was some new vitamin, which he called vitamin D.
