Why are some people more likely to get rickets?
A young couple acquitted of murdering their four-month-old son have called for an inquiry into two London hospitals responsible for his care.
Rohan Wray, 22, and Chana Al-Alas, 19, of London, were accused of abusing baby Jayden but his fractures were later found to have been caused by rickets.
They told the BBC that the Great Ormond Street and University College hospitals should have diagnosed the disease.
The hospitals have defended their care of Jayden before his death in 2009.
Dr Arun Ghosh, GP, explains how to spot rickets.