In order to build up bone substance, an adequate supply of phosphate, calcium and vitamin D is necessary. “If children are at risk of developing a deficiency in these mineralization components, for example due to a chronic intestinal disease, or if they have to take certain medications, parents and doctors should ensure that they have an adequate supply of calcium and vitamin D. Calcium is found mainly in milk and dairy products, but also in green vegetables such as cabbage, spinach, broccoli and leeks. The body needs vitamin D in order to absorb phosphate and calcium from the intestine, which is then available for the mineralization of bones and teeth. 80 to 90% of this vitamin is formed by the influence of UV-B light on the skin and is only slightly absorbed through food. In order for the skin to be able to produce the vitamin, about 15 minutes of direct sun exposure on the forearms and face is sufficient daily, from April to October. In winter and spring, we are dependent on an external supply of this vitamin, because sunlight in these seasons in our latitudes does not contain the UV-B spectrum necessary for vitamin D production in the skin. Milk, fish, mushrooms and eggs are also among the vitamin D suppliers, ”recommends Prim. Högler. By regular exercise, bone growth is also stimulated.