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DESCRIPTION
Calcium constitutes approximately 2% (by weight) of the
adult human body, with the overwhelming proportion of total body calcium in the
structure of the teeth and bones.
Calcium also plays an important metabolic role as a
cofactor to adenosine triphosphate (ATP), which is instrumental in the release
of energy for muscular contractions. It acts as an essential cofactor in
various enzymatic conversions which occur during blood clotting. It is also
essential for nerve transmission and the release of neurotransmitters at
neuromuscular junctions.
Calcium is instrumental in ion permeability across
membranes, influences the effects of protein hormones, is necessary for proper
myocardial function, and helps to preserve the integrity of intracellular
cement substances.
Scientific research has not conclusively shown calcium
deficiency to be the direct cause of any specific condition. However, several
clinical disorders such as rickets, osteomalacia, osteoporosis, and scurvy,
have been linked to abnormalities of calcium in structural bone. While
conclusive evidence is pending, tetany and hypertension have also been cited as
possible symptoms of calcium deficiency.
METHOD OF ACTION
Calcium phosphate constitutes the bulk of inorganic
matrix of bone. It is deposited within the soft, fibrous organic matrix as
hydroxyapatite, adding to the bone's structural rigidity.
Calcium is also one of the major mineral constituents of
tooth enamel and dentin, both of which serve as rigid exterior protection for
the sensitive interior pulp of the tooth. The vast majority of calcium
absorption takes place via active transport in the duodenum and is greatly
facilitated by the action of vitamin D, lactose, and high levels of dietary
protein.
Vitamin D deficient diets, diets high in fat, and High
Fiber Diets have the reputed effect of curtailing calcium absorption, which is
only 10 to 30% efficient under usual physiological conditions.
When serum blood levels of calcium fall, parathyroid
hormone is secreted. This stimulates increased absorption of calcium from the
intestine and resorption of calcium from the bone. However, high blood calcium
levels trigger the release of the hormone calcitonin, which induces renal
excretion of calcium and inhibits further resorption from the bone. The
mutuality of these two hormones allows a feedback control of calcium levels in
blood serum.
Consumption of dairy products, one of the primary food
sources of calcium, can decrease absorption of most tetracycline antibiotics,
with the notable exceptions of deoxycycline and minocycline.
Neomycin, cycloserine, erythromycin, sulfonamides,
tetracyclines, penicillin, isoniazid, and para-aminosalicylic acid reportedly
decrease calcium absorption to some degree.
PROPERTIES AND USES
Calcium has been used in the management of uremic bone
disease, a disorder in which chronic renal failure produces abnormally high
serum phosphate levels and, reciprocally, low serum calcium levels.
It is thought that unexplained calcium deficiencies may be
related to excessive magnesium depletion. Calcium supplementation helps to
prevent the excessive resorption of calcium from the bones. Experimentation has
shown that adequate calcium intake can prevent and, on occasion, reverse
resorption of bone in human periodontal disease.
Calcium and vitamin D supplements are effective in the
treatment of osteomalacia; vitamin D promotes increased calcium absorption
within the duodenum.
Although not a proven cure, increased calcium and vitamin
D intake is beneficial for the elderly with osteoporosis, as it counteracts the
high rate of calcium efflux characteristic of this disease. In conjunction with
vitamin D, calcium is effective in alleviating symptoms of vitamin D-dependent
rickets.
TOXICITY FACTORS
Although excessive calcium intake has not been shown to
be toxic, an extremely high intake of calcium in conjunction with a high intake
of vitamin D can induce hypercalcemia. This condition can result in excessive
calcification of bone and soft tissue (e.g., the kidney), or in the formation
of kidney stones.
RECOMMENDED DIETARY ALLOWANCES
RDA for male adults: 1,000 mg
RDA for female adults 800 mg
RDA for children 7 to 10 years 500 mg.
RDA for infants: 275 mg.
RDA for Pregnant and Lactating Women 1,000
mg
FOOD SOURCES
· Artichoke · Beet greens
· Broccoli · Beans (dried)
· Cheese · Collard greens
· Ice cream · Kale
· Milk · Okra
· Orange sherbet · Parsnip
· Rhubarb · Rutabaga
· Salmon · Sardines
· Spinach · Swiss chard
· Tangerine · Turnip greens
· Watercress
Calcium Deficiency Symptoms In Bones
· Early stage symptoms in bones:
· Pain in the joints
· Brittleness of bones
· Bones ache on exertion
· Retarded bone and tooth
mineralization
· Fragile bones
· Osteomalacia
· Rickets
· Stunted growth
· Osteoporosis
Symptoms of Deficiency of Blood Calcium:
· Over susceptible excitability of
nerves and muscles
· Loss of muscle contraction
ability, including the heart muscle. Also loss of ability of the muscles to
relax
· Pain in the feet making walking
painful or impossible
· Loss of integrity of the
cement-like substances that hold body cells together
· Incorrect functioning of cell
membranes
· Schizophrenia in high histamine
types (histadelics)
· Reduced control of blood
cholesterol
· Becomes difficult to hold objects
· Muscles lose tone and become
flaccid
· Unbalanced hormone release
· Poor lactation of nursing mothers
· Face twitches
· Poor blood clotting
· Irritability
· High blood pressure
· Nervousness
Notes
· Extra calcium decreases zinc
absorption if taken at the same time as a zinc supplement.
· Smoking decreases calcium
absorption as the cadmium in cigarette smoke is a calcium antagonist.
· High protein diets (120 grams or
more per day) stimulate bone calcium resorption and encourage long term bone
loss. To avoid such a loss reduce your consumption of phosphorus rich meats and
soft drinks, and eat more fruits, vegetables, grains and dairy products.
· The more indigestible the form of
protein we consume the more apt we are to have a calcium deficiency. |
