Cod-liver oil, vitamin D and the fight against rickets.

Although rickets has all but disappeared as a medical problem, the disease caused serious concern in turn-of-the-century England, where it reached epidemic proportions. The connection between rickets and a lack of vitamin D wasn't made until shortly after World War I, when it was determined that regular exposure to sunlight would eliminate the problem; another solution was to provide vitamin D supplements in milk. The problem hasn't disappeared entirely, however. Seventeen cases of rickets have been diagnosed at Toronto's Hospital for Sick Children in the past 5 years.