Healthfull Facts

Relationships of Calcium and Magnesium

Both minerals require each other for proper absorption and utilization and
must be provided in adequate amounts. Depending upon the physiological
environment,there are cases in which the roles of these two minerals are
antagonistic to each other. Magnesium is located inside the cell -
(intracellular) ,while calcium is predominantly located outside the cell
(extracellular). Consequently, the role of magnesium in intracellular
metabolic functions, such as energy production, respiration, and muscle
contraction-relaxation is antagonistic to calcium.

Let us briefly examine the role and relationship of these two minerals in
known clinical studies:

REGULATION OF HEART BEAT

The heart is a muscle and its primary function is to pump blood throughout
the body. The heart is composed of billions of cells, each of which
works as a electrochemical generator, and contains both calcium and
magnesium. On the outer surface of the heart cells, thin fibers made of a
substance called"Actin", continually expand and contract in unison with the
heartbeat. The Actin fibers are stimulated by calcium, and then relaxed
by magnesium. An electrical charge produced by magnesium then pushes
the calcium to the opposite side of the cell. Thus, calcium helps to
produce the heartbeat, and magnesium regulates it.

MYOCARDIAL INFARCTION (Heart Attack)

* Several researchers have shown that a heart failure involves drastic
changes in the concentration of cardiac electrolytes (1). During cardiac
stress, some of the magnesium is moved out of the cell accompanied by
an influx of calcium into the cell. Thus, the cardiac muscle shows a 20%
decrease in magnesium and a 41/2 fold increase in myocardial calcium
(2). The loss of magnesium and an influx of calcium seriously disrupts
the energy potential of the affected muscle (3). The situation can be
prevented by increasing the level of magnesium. In clinical practice,
intravenous or intramuscular administration of magnesium salts has
proven very useful and is highly regarded (4). It is known that
magnesium therapy is the most effective to protect myocardial integrity
during cardiac arrest (4,5). It is interesting to note that in Canadian
surveys of postmortem tissue composition, about 24% less magnesium
was found in chemic hearts than in non-cardiac cases (6).

ATHEROSCLEROSIS (Heart Disease)

* A high dietary intake of magnesium has been attributed to why heart disease is

virtually unknown among Bantu tribesman of South Africa while the disease is
prevalent among white South Africans. Clinical studies have revealed that the
Bantu's serum magnesium level is about 11% higher than in the white South
Africans. The Bantu's high dietary intake of magnesium is largely attributable
to intake of unrefined cereals such as maize meal, which has a high magnesium
content and also has a high fiber content (12). Also, it has been shown that
the ability of high-fat diets to induce atherosclerosis is prevented by a high
magnesium dietary regime (7).

HYPERTENSION (High Blood Pressure)

For many years, hypertension has been associated with sodium. Consequently,
the disorder is treated by substituting potassium in the diet. However, most of us
do not realize that magnesium is also considered a well-known vasodilator. The
anti-hypertensive effect of magnesium is achieved by a direct effect on the
vascular wall or is mediated through the central nervous system (8). Magnesium
competes with calcium for binding sites and the net result is that magnesium
reduces the calcium-induced contractions. It is well established that magnesium
infusions can cause vasodilation and reduce hypertension in humans (9).

UROLITHIASIS (Kidney Stones)

* Canadians appear to have a very high incident of kidney stones and the
occurrence is particularly high in Newfoundland (11, 12). In U.S., South
Carolina has the highest urolithiasis rate. South Carolina also has the highest U.
S. Rate for cardiovascular deaths (10). Both Newfoundland and South Carolina
regions have "very soft" drinking waters with little magnesium (11).

In Canada, calcium urolithiasis accounts for 70 to 80% of the total kidney-stone
problems (12). In the U.S., about 67% of all kidney stones are composed of
calcium oxalate or calcium hydroxy apatite (11).
Several researchers have used the magnesium/calcium ratio as an index of
susceptibility of urine to form kidney-stones in patients (10,13,14). In
general, patients with a urinary magnesium/calcium ratio of 0.7 is normal,
whereas a value lower than 0.7 may be considered as stone-forming. The ratio is
especially low in the Canadian "Kidney Stone Patients", indicating inadequate
magnesium intake.

INFANT DEATH SYNDROME (Sids or Crib Death)

* Magnesium deficiency has a primary role in sudden unexpected
infant-death syndrome. The sequence-of-events are as follows:
Magnesium deficiency causes calcium-dependant release of histamine
which, in turn, induces increased release of acetyl choline (especially
high calcium/magnesium ratio). The increased amount of acetyl choline
leads to symptoms of neuromuscular hyper irritability and convulsions
that can lead to reduced heart rate (15). The sudden-death syndrome is
puzzling since no recognizable allergens are involved. The symptoms
are acute respiratory distress, and includes bronchospasm, shortness of
breath, and eventual circulatory collapse. Hypomagnesemia is observed
throughout this syndrome. Therefore, the role of magnesium in the infant-
death syndrome is very significant.

NUTRITIONAL STATUS OF MAGNESIUM

* The recommended dietary allowance for magnesium is 300 to 450 mg/day.
There are several factors including pregnancy, rapid growth, or a high intake of
protein, vitamin D, calcium, fat, carbohydrates or alcohol, that will increase the

requirement for magnesium.Surveys of dietary magnesium intake from different
countries show a prevalence of lower magnesium intake than the desired levels.
In Newfoundland, the intake is only 50% of the recommended amount (16,17).
Other reports (40) show that hospital and institutional diets contain only 61 and
68% of the recommended intake, respectively. In other studies (18,19), it was
found that the intake for pregnant women was only 45 to 60% of the
recommended allowances. There is definite evidence that magnesium intake is
suboptimal or marginally inadequate in regions of the Western World (20). The
occurence of hypomagnesemia in humans, due to low magnesium intake and
due in part to factors such as, prolonged use of diuretics, alcoholism, pregnancy
etc., have been shown to be more prevalent that generally believed (21).

CONTRIBUTION OF DRINKING WATER

* Drinking water can significantly contribute to magnesium intake and hard waters

can supply 9 to 29% of the daily magnesium intake (23). Because of the
metabolic antagonism between magnesium and calcium, the ratio between these
two minerals in the drinking water is of considerable significance. In a survey of
25 U.S. Cities, the lowest death rates from coronary disease were found in areas
where the drinking waters supplied more magnesium and less calcium than the
U.S. Average (24).Australia has the highest cardiovascular death-rate in the
world and also consumes some of the worlds softest drinking waters (60). On
the other hand, the Western region of Texas has the hardest drinking waters and
the lowest cardiovascular mortality rates in the United States (25).

Relationship between death-rates from coronary heart disease and the
average dietary calcium/magnesium ratio in several countries (26).
The high mortality rate in Finland is associated with a high calcium/magnesium
ratio (62), while the low mortality rate in Japan is related to a low
calcium/magnesium ratio as well as to the "protective" effect conferred by the
alkalinity (carbonate-biocarbonate content) of water.

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