Calcium is the most abundant mineral in the body and is essential for many vital functions. For healthy bones and teeth, calcium is needed along with some other nutrients such as vitamin D and vitamin K.
Calcium also plays an important role in many systems such as metabolic processes, information transmission through the nervous system, control of muscle contraction, and intracellular signal transmission to ensure blood coagulation.
The skeleton contains about 99% of the body’s calcium. The body’s need for calcium varies with bone growth rate. Thus, the skeleton acts as a “mineral bank” from which calcium and phosphorus can be continuously extracted or stored to support physiological needs as well as protection of vital organs.
Calcium levels are balanced by the absorption of calcium from the gut, excretion through the kidneys, and storage in bone. These areas are regulated by feedback mechanisms controlled by many hormones, including parathyroid hormone and the active form of vitamin D.
Vitamin / Mineral Deficiency is usually defined by low blood levels of that vitamin / mineral, but low levels of calcium in the blood are rare. This is because the body extracts calcium from the bones, which act as a reservoir to maintain blood calcium levels. This condition is reflected in bone density.
In addition, insufficient calcium in the bones can be due to insufficient intake of vitamin D, which is needed to absorb calcium.
Adequate calcium intake is critical, especially during growth (childhood, adolescence, pregnancy) and breastfeeding.
Calcium can be obtained from milk, dairy products, some green leafy vegetables such as broccoli and kale, and some edible fish such as sardines.