CHAPTER 2: The Biological Roles of Calcium: Nutrition, Diseases and Analysis

Calcium is an alkaline-earth metal with atomic number 20 and the fifth most abundant element by mass in the Earth's crust, being one component of several common mineral salts. This mineral is important in plant physiology as well as to several metabolic and cellular functions of the human organism, as well as to the formation of bone tissues. Insufficient calcium intake may lead to the development of osteoporosis. On the other hand, the excessive ingestion of calcium increases the risk for renal calculus and intestinal constipation. The presence of calcium in the blood is regulated by vitamin D and by the hormones calcitonin and parathormone.