Calcium is the most abundant mineral in the human body. Of the body's total calcium, about 99% is in the bones and teeth where it plays a structural role. The remaining 1% is present in body tissues and fluids where it is essential for cell metabolism, muscle contraction and nerve impulse transmission.
The main function of calcium is structural. The skeleton of a young adult male contains about 1.2kg of calcium. There is continuous movement of calcium between the skeleton and blood and other parts of the body. This is finely controlled by hormones. Metabolites of Vitamin D are important in this, increasing reabsorption of calcium by bones.
Calcium also plays a role in cell biology. Calcium can bind to a wide range of proteins altering their biological activity. This is important in nerve impulse transmission and muscle contraction. Calcium is also needed for blood clotting and activating clotting factors.
Some research has indicated that vegetarian women are at less risk of osteoporosis than are omnivorous women. This is thought to be due to animal protein increasing calcium loss from bones. However, other research has found no difference between vegetarians and omnivores.
A low level of calcium in the blood and tissues can cause hypocalcemia. This involves sensations of tingling and numbness and muscle twitches. In severe cases muscle spasms may occur, called tetany. It is more likely to be due to a hormonal imbalance in the regulation of calcium rather than a dietary deficiency.
People aged 19 to 50 should be getting 1000mg of calcium per day in the form of low oxalate greens, fortified foods or dairy products. Put another way, if you are aged 19-50 and are not drinking three cups of calcium-fortified soy milk, orange juice or milk, or eating three cups of greens every day then you should consider taking calcium supplements.
During pregnancy, calcium absorption from the gut increases and no additional calcium is generally needed. Pregnant adolescents are an exception to this, having particularly high calcium needs. Breastfeeding women need an extra 550mg of calcium daily; a lactating woman can lose up to 300mg per day in breast milk.
The NIH recommends a calcium intake of 1000mg per day for pre-menopausal women and post-menopausal women on estrogen replacement therapy (ERT). If post-menopausal women are not on ERT, their calcium intake should be 1500mg per day.
Calcium absorption decreases with age so it is important that the elderly receive adequate dietary calcium.
There are a large variety of calcium supplements available, and if you are searching for one, you should keep in mind the following:
Vitamin D is needed for absorption of dietary calcium and so calcium deficiency may be linked to rickets in children. In adults, calcium deficiency may lead to osteomalacia (softening of the bones). This may be related to repeated pregnancy with lengthy breast feeding.
Osteoporosis can be due to calcium deficiency. This involves loss of calcium from the bones and reduced bone density. This causes bones to be brittle and liable to fracture. Bone loss occurs with age in all individuals. This usually occurs after 35-40 years and involves the shrinking of the skeleton. Bone loss is greatest in women following the menopause. This is due to reduced levels of the hormone, estrogen. Postmenopausal women are particularly at risk from osteoporosis.
Cheraskin & Ringsdorf (1970) studied the effects of nutritional supplements on teeth grinders or clenchers. Of these, 16 took calcium, vitamin A, vitamin C, Vitamin B5 (pantothenic acid), iodine, and vitamin E. When surveyed a year later, they reported that bruxism vanished. In contrast, the 15 bruxers who only took vitamins A, C, E and iodine showed no improvement. It seemed reasonable to conclude that the active agents were calcium and pantothenic acid (vitamin B5).
A calcium deficiency can cause various food cravings, including a craving for fats and oils.
When body stores of calcium are low, the body must draw calcium from the bones in order to avoid serious complications.
Mineral metabolism of 19 patients with hair loss was examined. Eighteen of those patients showed considerable problems with calcium absorption. Specific nutritional and mineral therapy resulted in improved hair growth after 2-3 months of treatment. [Blaurock-Busch, E. Wichtige Nahrstoffe fur Gesunde Haut und Haare, Kosmetik Internat. 3/87]
The carbonation in soft drinks causes calcium loss in the bones through a three-stage process:
But the story doesn't end there. Another problem with most soft drinks is that they also contain phosphoric acid (not the same as the carbonation, which is carbon dioxide mixed with the water). This substance also causes a drawdown on the store of calcium.
Soft drinks soften your bones (actually, they make them weak and brittle) in three ways:
Those aged 19 through 50 who are not getting at least 1000mg of calcium per day through low oxalate greens, fortified foods such as orange juice, soy milk or dairy products probably have a calcium requirement.
Calcium supplements are best taken between meals, ideally right before bed. Since you can only absorb about 500mg at a time, you may want to use divided doses. Drink a full glass of water or juice with them. The form of calcium does not really matter – calcium carbonate or calcium citrate – just don't use the dolomite form, which may be contaminated with lead. Some people simply take generic TUMS, which is fine. Studies show that calcium carbonate works just as well as the high profit margin supplements that you can buy.
NOTE: Calcium supplements may interfere with prescription medications or other supplements that you are taking, so try to avoid taking them within a few hours of any other pills.
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