PISA, ITALY—An examination of the remains of nine of the Medici children, found buried beneath the floor of Florence’s Basilica of San Lorenzo, reveal that six of these privileged youngsters suffered from rickets, a bone disease caused by a lack of vitamin D. Eating foods such as eggs and cheese and exposure to sunlight are necessary for vitamin D production in the body. An analysis of the children’s bone collagen showed that following Renaissance customs, these children had not been weaned until the age of two. Historic texts suggest that breast milk was supplemented with a mixture of soft bread and apples. As members of a wealthy family, the Medici children probably spent little time outdoors. And because even newborn infants suffered from soft bones, their mothers probably also lacked vitamin D.