Calcium is the most abundant mineral in the human body. Over 99% of the body's calcium is found in bones and teeth which consists mainly of hydroxyapatite crystals (about 40% calcium and 60% phosphorus). The remainder is found in blood, bodily fluids, muscle, and other tissues where it plays a role in blood vessel contraction and dilation, muscle contraction, nerve transmission, and glandular secretion.
Calcium is probably most recognized for it's important role in maintaining bone health. The skeleton not only provides structural support for muscles, it protects vital organs and serves as a storage site for calcium.
Calcium is a major structural element in bones and teeth. The mineral component of bone consists about 40% calcium and 60% phosphorus. Bone is a dynamic tissue that is constantly remodeled throughout life. The process involves resorption (old bones is removed) and formation (new bone is formed).
Calcium and Osteoporosis
Bone cells called osteoclasts begin the process of remodeling by dissolving or resorbing bone. Bone-forming cells called osteoblasts then synthesize new bone to replace the bone that was resorbed. During normal growth, bone formation exceeds bone resorption. Osteoporosis may result when bone resorption exceeds formation. Osteoporosis is a debilitating disease affecting more than 25 million Americans where 80% of them are women.
Osteoporosis is caused by low bone mass and the structural deterioration of bone tissue, leading to bone fragility and an increased susceptibility to fractures of the hip, spine, and wrist. There are several reasons that cause Osteoporosis, the most popular one is deficiency in calcium. When the level of calcium in our bones drops below a certain limit, Osteoporosis may occur. In addition to calcium, magnesium and vitamin D are also needed to prevent osteoporosis.
Benefit of Calcium
Calcium plays a role in mediating the constriction and relaxation of blood vessels, nerve impulse transmission, muscle contraction, and the secretion of hormones, such as insulin. Excitable cells, such as skeletal muscle and nerve cells, contain voltage-dependent calcium channels in their cell membranes that allow for rapid changes in calcium concentrations.
For example, when a muscle fiber receives a nerve impulse that stimulates it to contract, calcium channels in the cell membrane open to allow a few calcium ions into the muscle cell. These calcium ions bind to activator proteins within the cell that release a flood of calcium ions from storage vesicles inside the cell. The binding of calcium to the protein, troponin-c, initiates a series of steps that lead to muscle contraction. The binding of calcium to the protein, calmodulin, activates enzymes that breakdown muscle glycogen to provide energy for muscle contraction.
Calcium is necessary to stabilize or allow for optimal activity of a number of proteins and enzymes. The binding of calcium ions is required for the activation of the seven "vitamin K-dependent" clotting factors in the coagulation cascade. The term, "coagulation cascade," refers to a series of events, each dependent on the other that stops bleeding through clot formation (see Vitamin K).
Food With Calcium Source
Calcium is found in a variety of foods, in particular, dairy products contain rich calcium. The following is a list of the natural food sources with calcium:
Brazil Nuts
Milk
Cheese
Caviar
Kelp
Pudding
Canned Salmon
Canned Sardines
Turnip Greens and Yogurt
Note that not all calcium sources are alike. Calcium may be poorly absorbed from foods high in oxalic acid such as spinach, sweet potatoes, beans or rhubarb and phytic acid such as unleavened bread, nuts, raw beans, grains and soy isolates.
