Calcium

All cells need calcium, but more than 99% of the calcium in the body is used to strengthen bones and teeth. The calcium circulating in the bloodstream supplies the calcium needs of body cells.


Many factors enhance calcium absorption, including:
• Blood levels of parathyroid hormone
• The presence of glucose and lactose in the diet
• The gradual flow (motility) of digestive contents through the intestine

Several factors limit calcium absorption, such as:
• Large amounts of phytic acid in fiber from grains
• Great excess of phosphorus (and possibly magnesium) in the diet
• Polyphenols (tannins) in tea
• Vitamin D deficiency
• Diarrhea
• Old

Calcium is essential for forming and maintaining bones, blood clotting and for muscle contraction, regulating cellular metabolism by influencing the activities of various enzymes and hormonal responses, nerve function.


Calcium is also present in extracellular fluid (the liquid around body cells),
where it performs the following duties:

• Regulating fluid balance by controlling the flow of water in and out of cells

• Enabling cells to send messages back and forth from one to another

• Keeping muscles moving smoothly and preventing cramping

An adequate amount of calcium is important for controlling high blood pressure. Also, adequate calcium intake can reduce the risk of colon cancer, kidney stones, hypertension, high blood cholesterol, obesity.

Calcium sources are milk, cheese (except cottage cheese), bread, rolls, crackers, spinach, broccoli, sardines, and canned salmon.