Vitamin D is essential for skeletal development in children. It was discovered as a nutritional factor ameliorating rickets, a skeletal disease in childhood. Vitamin D is not only obtained from limited foods but also synthesized in the skin under exposure to ultraviolet B ray, exceptionally as vitamin. Vitamin D deficiency in infants and children results in rickets and hypocalcemic seizures. Vitamin D deficiency rickets is characterized by defective mineralization of bones and cartilage of the growth plate, low circulating 25-hydroxyvitamin D concentration, hypophosphatemia, hypocalcemia, and increased serum parathyroid hormone and alkaline phosphatase levels. An increase in the patient with symptomatic vitamin D deficiency, including rickets and/or hypocalcemia, among children has been reported in all over the world, including Japan. We have recently reported the result of the nationwide survey on the incidence rate of symptomatic vitamin D deficiency in Japanese children. Risk factors for vitamin D deficiency rickets include maternal vitamin D deficiency, exclusive breast-feeding, inappropriate complementary feeding, malnutrition, high latitude, dark skin and restricted sun exposure. It is thought that low calcium diet enhances the development of rickets. Vitamin D deficiency does not occur uncommonly by any means. There is a need to continue actively to publicize that vitamin D is an important vitamin for health, especially healthy growth.
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