A deficiency of vitamin D in children causes the bone-softening disease called rickets.
Vitamin D helps the body absorb calcium and phosphate, minerals needed to harden and mineralize growing bones. When vitamin D is insufficient, the growth plates and newly formed bone do not mineralize properly. This can make bones weak and soft, leading to bowed legs, bone pain, delayed growth, muscle weakness, or skeletal deformities.
Rickets is the childhood counterpart of osteomalacia, the related bone-mineralization disorder in adults. It is not the same as osteoporosis, in which bone becomes less dense and more fragile, particularly because of increased bone loss. Rickets can also result from inadequate calcium or phosphate, malabsorption, kidney disease, or inherited conditions—not only from vitamin D deficiency.
Historically, rickets became widespread in industrializing cities where children had poor diets and limited sunlight. Vitamin D production in skin requires ultraviolet B radiation, and foods such as fatty fish and fortified milk can supply additional vitamin D. Treatment depends on the cause and commonly includes vitamin D and calcium under medical guidance.