Calcium is the most abundant mineral in the human
body. Of the body’s total calcium, about 99 percent is in the bones and
teeth where it plays a structural role. The remaining 1 percent is present
in body tissues and fluids where it is essential for cell metabolism,
muscle contraction and nerve impulse transmission.
The structural function of calcium is vital to the skeleton. There is a
continuous movement of calcium between the skeleton, the blood and other
parts of the body. This movement is controlled by hormones.
Calcium also plays a role in cell biology, as it affects the proteins
in the body which in turn affect nerve impulse transmission and muscle
contraction. Calcium is also needed for blood clotting.
Vitamin D is necessary to promote absorption of dietary calcium.
Calcium deficiency may be linked with rickets in children and osteomalacia
(soft bones) which may also be caused by repeated pregnancies with lengthy
breast feeding.
Osteoporosis can be due to calcium deficiency in that there is a loss
of calcium from the bones and a reduction in bone density. Bones become
brittle and are liable to fracture. This occurs with age in all
individuals, usually after 35-40 years of age and involves the shrinking
of the skeleton. Bone loss tends to be greatest in women following
menopause when there is a reduced level of the hormone estrogen.
Postmenopausal women are, therefore, particularly at risk. Some research
has indicated that vegetarian women are at less risk of osteoporosis than
omnivorous women, due to animal protein increasing calcium loss from
bones; however, other research has refuted this indication. Other factors
than diet affect osteoporosis, namely lack of exercise, being underweight,
smoking, and consumption of alcohol can all increase the risk.
Low level of calcium in the blood and tissues can further affect the
muscles. This condition is called hypocalcaemia. It brings about the
sensation of tingling, numbness and muscle twitching, sometimes resulting
in sever muscle spasms, however, this latter condition can be due to a
hormonal imbalance in the regulation of calcium rather than dietary
deficiency.
Not only can the body have calcium deficiencies, but it can have an
excess of calcium in the blood, resulting in nausea, vomiting and calcium
deposits in the heart and kidneys. This may result from an excess of
vitamin D.
U.S. Consumer Healthcare, Research and Development