B I N A R A G A . I N F O

Calcium

Calcium is the most abundant mineral in the body. It is essential for the developement and growth of bones and teeth, the functioning of nerves, and the clotting of blood. It also regulates muscular contraction and relaxation (including that of the heart muscle), and activates various important enzymes. Calcium is especially important during times of rapid growth - pregnancy, lactation, infancy, childhood, and adolescence. About 99% of the body's calcium is in the bones and teeth, the rest is in the soft tissues and bodily fluids.

Calcium deficiency can result in rickets (stunted bone growth) in children. In adults it can result in osteomalacia (soft bones) or osteoporosis (porous bones). Calcium deficiency is not necessarily caused by insufficient calcium. It can also be due to insufficient vitamin D (which is needed to properly absorb and metabolize calcium), high oxalic acid intake (from foods such as spinach and silverbeet), excessive caffeine intake, or a number of other factors. Among the osteoporosis risk factors are gender (men get less osteoporosis), estrogen levels, weight (heavier women are less likely to develope osteoporosis and their fat tissue is a major source of estrogen), physical activity (weight-bearing exercises decrease the risk), cigarette smoking, alcohol intake, weak lower-leg muscles (increases the risk fourteen-fold), and the intake of other minerals involved in calcium metabolism. As a result of the increased concern about osteoporosis, many post-menopausal women are now being prescribed calcium supplements.

Calcium in supplements always comes in combination with other chemicals, the most common forms are calcium carbonate, calcium lactate, calcium gluconate, dicalcium phosphate, calcium citrate, ground oyster shell, bonemeal, and dolomite. Calcium carbonate contains about 40% calcium, but is not easily absorbed by individuals who lack sufficient stomach acid (common in the elderly). It may also cause constipation. Bonemeal, oyster shell and dolomite may be contaminated with heavy metals such as lead, mercury, arsenic, and cadmium, and so should be avoided.

Studies of supplements have revealed that of all the calcium supplements available, calcium citrate is the most efficiently absorbed by the body, contributes less to kidney stone formation, and has the fewest gastro-intestinal side-effects. Some calcium supplements come with vitamin D, which is needed for the body to properly metabolize calcium. With these supplements, it is important that you don't exceed the RDI (US: RDA) for vitamin D whilst trying to meet your calcium needs, Since an overdose of vitamin D can be toxic. Do not take calcium supplements with meals (unless otherwise instructed by a doctor) as they may hinder the absorption of iron, zinc, copper, and magnesium. Take them with a glass of milk or orange juice. The vitamin D or citric acid will aid in their absorption. In susceptible people, calcium supplements of 1000-1500mg a day may cause kidney stones. If your family has a history of kidney stones then calcium supplements should only be taken under medical supervision. Large doses (above the RDI) taken regularly without medical supervision may cause constipation, nausea, a hyperactive stomach, lethargy, mental confusion, calcium deposits in the soft tissues of the body, muscle and abdominal pain, and kidney disease. And calcium deposits can build up on the walls of blood vessels, leading to blockages and heart attacks.