Vitamin D is essential for bone development and maintenance, for its role in assisting calcium absorption from food in the intestine and ensuring bone tissue's correct renewal and mineralization. People who have decreased vitamin D serum levels run the risk of first acquiring osteopenia. Untreated osteopenia may lead to osteoporosis due to reduced calcium absorption, thus increasing their risk of bone fractures (the diagnostic difference between osteopenia and osteoporosis is the measured decrease of bone mineral density).
