What gives lightness and strength to human bones? How does human bone composition change with age?

Lightness and strength of human bones is given by a special chemical element – calcium. Therefore, throughout life, the body needs calcium intake. However, calcium is not assimilated in the absence of vitamin D. The source of calcium for humans is dairy and fermented milk products, in case of an acute deficiency, crushed chicken egg shells can be consumed. The source of vitamin D is sunlight. Under its influence, this vitamin is produced in the skin. As a person ages, the process of calcium leaching from the body occurs and the bones become more fragile.