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Medicina Sportiva (2015), vol. XI, no 1, 2482-2494
Journal of the Romanian Sports Medicine Society
Magnesium supplementation in top athletes - effects and recommendations
Adriana Sarah Nica¹, Adela Caramoci², Mirela Vasilescu3, Anca Mirela Ionescu², Denis Paduraru4,
Virgil Mazilu4
¹Departament of Rehabilitation, University of Medicine and Pharmacy Carol Davila, Bucharest,
Romania
²Departament of Sports Medicine, University of Medicine and Pharmacy Carol Davila, Bucharest,
3Department of Kinetotherapy and Sports Medicine, University of Craiova,
³National Institute of Sports Medicine, Bucharest, Romania
Abstract. Magnesium is a cofactor involved in many enzymatic systems, being necessary for protein
synthesis, functioning of nervous and muscular systems, regulation of blood pressure and glycaemia, bone
metabolism. A low dietary intake of magnesium is very common in general population. Additionally, there
are categories of population that are even more predisposed to hypomagnesaemia. Top athletes represent a
population category predisposed to magnesium deficiency due to increased urinary and sudorific losses, and
in case of heavyweight disciplines, due to a decreased dietary intake. Many studies supported the role of
magnesium in athletic performance and showed that magnesium increased the physical endurance and
improved the force indices and muscle metabolism in athletes that had a rich diet in magnesium or received
magnesium supplements. It is still uncertain whether the positive effects of magnesium supplementation in
athletic performance are due to pharmacological actions of magnesium itself or to the reversal of a pre-
existing magnesium deficiency. Therefore, the purpose of this article is briefly review of Magnesium
importance in human health and athletics performance, various hypotheses that may explain magnesium's
physiologic action mechanisms but also possible pathways for magnesium deficiency’s correction.
Key words: magnesium, athlete, deficiency, supplementation.
Some basics of Magnesium
Magnesium is the second most abundant mineral
in cells after potassium, but the two ounces or so
found in the typical human body is present not as
metal but as magnesium ions (positively-charged
magnesium atoms found either in solution or
complexed with other tissues, such as bone).
Roughly one quarter of this magnesium is found
in muscle tissue and three-fifths in bone; but less
than 1% of it is found in blood serum, although
that is used as the commonest indicator of
magnesium status.
This blood serum magnesium can be further
subdivided into free ionic, complex-bound and
protein-bound portions, but it's the ionic portion
that's considered most important in measuring
magnesium status, because it is physiologically
active.
The importance of magnesium as an essential
nutrient has been emphasised as early as 1932 by
Kruse et al., who induced an acute magnesium
deficiency in rats by limiting the dietary intake of
this element to 0.09mEq/kilogram. Hypo-
magnesaemia produced hyperemia,
neuromuscular progressive irritability that
eventually precipitated fatal convulsions in these
animals (1).
The role of Magnesium in the body
Mg is a cofactor involved in many enzymatic
systems (more than 300 biochemical reactions),
being necessary for protein synthesis, functioning
of nervous and muscular systems, regulation of
blood pressure and glycaemia, bone metabolism
(2-4). Most studies regarding magnesium
metabolism and homeostasis have shown that
magnesium interferes with transmembrane
sodium and potassium ion flow in smooth muscle,
which explains its involvement in many
physiological processes and why magnesium
deficiency is linked to many pathological
conditions of the cardiovascular, skeletal and
nervous systems (5-7).
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It also affects the active transmembrane transport
of calcium and potassium ions, being a known
calcium-channel blocker, and through these
processes influences nerve conduction, muscular
contraction and cardiac rhythm (4).
Its presence is necessary for both aerobic
(oxidative phosphorylation) and anaerobic
(glycolysis) energy production processes, both
indirectly, as a component of ATP-Mg complex
and directly, as an enzymatic activator (8).
It plays an important role in cell division,
participating in DNA, RNA and glutathione
synthesis (9).
It is essential in osteoblasts and osteoclasts
functioning, vitamin D activation, calcitonin
release and suppression of parathyroid hormone
release (10). Magnesium depletion disturbs
calcium homeostasis, hypocalcaemia being
sometimes determined by a moderate or severe
deficiency of Mg. The inadequate intake of
magnesium stimulates extracellular depositions of
calcium (calcifications). Although Mg deprivation
increases intestinal absorption and renal
reabsorption via a still unknown mechanism, if
this process continues, Mg in bones will play a
major role in maintaining a normal extracellular
level of magnesium and up to 30% of intra
osseous magnesium can be mobilized for this
purpose. Research has shown that it is important
to maintain an optimal ratio between calcium and
magnesium intake, whose ideal value is 1:1.
These mechanisms can explain the significant
correlations between magnesium level and bone
density, published by some authors (11, 12) and
why they recommend Mg supplementation for
menopausal women as a way to prevent
osteoporosis (13).
A group of researchers from the Department of
Cognitive Sciences of the Massachusetts Institute
of Technology has shown that Magnesium
regulates the activity of a key receptor involved in
memory and learning processes and that a normal
level of Magnesium in the cerebrospinal fluid is
essential for maintaining the plasticity of the
cerebral synapses. The authors claimed that an
increase of magnesium level in the brain would
ameliorate the cognitive processes and memory
(14). In fact, the authors of an earlier study (1996)
also reported positive effects after magnesium
administration to children with ADHD. These
effects were attributed to an improvement in
cerebral activity and a sedating effect of
magnesium on CNS (15).
Recommended dietary allowances for
Magnesium and sources of magnesium
The UK recommended intake for magnesium (the
daily amount deemed adequate to prevent
deficiencies in 97.5% of the UK population) is set
at 300 mgs for men and 270 mgs for women (16).
The US has recently revised its figures upwards
and now recommends an intake of 400 mgs per
day for men aged 19-30 and 420 for those over
30; the figures for women under and over 30 are
300 and 310 mgs per day respectively (16, 17).
However, some investigators believe these should
be set even higher at 450-500mg/day (18).
Daily allowance of magnesium has been set by
the Institute of Medicine in Washington in terms
of age and sex (see table I) (19).
Table I. Recommended Dietary Allowances (RDAs) for Magnesium (1)
Age
Male
Female
Pregnancy
Lactation
Birth to 6 months
30 mg*
30 mg*
7–12 months
75 mg*
75 mg*
1–3 years
80 mg
80 mg
4–8 years
130 mg
130 mg
9–13 years
240 mg
240 mg
14–18 years
410 mg
360 mg
400 mg
360 mg
19–30 years
400 mg
310 mg
350 mg
310 mg
31–50 years
420 mg
320 mg
360 mg
320 mg
51+ years
420 mg
320 mg
Institute of Medicine (IOM). Food and Nutrition Board. Dietary Reference Intakes: Calcium, Phosphorus,
Magnesium, Vitamin D and Fluorideexternal link icon. Washington, DC: National Academy Press, 1997.
*Adequate Intake (AI)
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Foods with increased content of fibres, such as
vegetables, spinach, seeds, nuts and whole grains
are reach sources of magnesium (4). Fruit, meat
and fish supply poor levels, as do refined foods.
Magnesium is a fairly soluble mineral, which is
why boiling vegetables can result in significant
losses; in cereals and grains, it tends to be
concentrated in the germ and bran, which explains
why white refined grains contain relatively little
magnesium by comparison with their unrefined
counterparts (20). Contrary to common belief,
milk and dairy products are not particularly rich
sources of magnesium. The magnesium content of
plant foods tends to reflect soil magnesium
concentrations and growing conditions, especially
as magnesium is not routinely added to soils by
farmers during intensive fertilization (21). Water
also contains magnesium in different proportions
from 1/mg/l to more than 120 mg/l (22).
From the total dietary intake of magnesium, only
30-40% is intestinally absorbed (3).
Magnesium deficiencies
Many people fall short of optimum magnesium
intakes, and this has been confirmed in a number
of studies. Dietary intakes of magnesium in the
United States have been declining over the last
100 years from about 500 mg/day to 175-
225mg/day (23) and amore recent national survey
suggested that the average magnesium intake for
women is as low as 228mgs per day (24). But
since this figure is derived using a one-day diet
recall method, it may actually be an overestimate
of actual magnesium intakes (25). American
researchers found that more than 60% of US
adults were failing to meet even the previous
(lower) RDA for magnesium (26). Recent data
provided by the National Health and Nutrition
Examination Survey (NHANES) have shown that
the diet of most Americans included suboptimal
levels of magnesium, except for those who took
magnesium supplements (27, 28). Another study
published in 2005, showed that 2/3 of Americans
have a dietary intake of magnesium below the
recommended minimal level, 19% of them even
below half of this level (29). Meanwhile, the UK's
Food Standards Agency estimates that the average
daily intake of magnesium in Britain for both men
and women is just 227 mgs - only two thirds of
the US recommended daily amount (RDA).
Risk groups for magnesium deficiency. Although
magnesium is considered an effective treatment
for many severe diseases, (diabetes, asthma, high
blood pressure, metabolic syndrome,
preeclampsia and eclampsia, etc.), it is still
uncertain whether the positive effects of
magnesium supplementation in these medical
conditions are due to pharmacological actions of
magnesium itself or to the reversal of a pre-
existing magnesium deficiency, responsible for
their etiology or pathogenesis. This hypothesis is
very probable, since a low dietary intake of
magnesium is very common in general
population.
Additionally, there are categories of population
that are even more predisposed to
hypomagnesaemia, because magnesium
homeostasis involves the intestine, kidney and
osseous system, and the physiological
disturbances of these organs affect magnesium
metabolism (30).
Magnesium absorption takes place mostly in
jejunum and ileum via an active transcellular
diffusion process and a passive mechanism
mediated by a cationic electrochemical gradient.
Intestinal malabsorption caused by Chron’s
disease, celiac disease, enteritis and surgical
removal of small intestine, especially ileum (small
bowel syndrome), can induce hypomagnesaemia
(3). The proton pump inhibitors, used to treatment
of hyperacidic gastritis, gastric and duodenal ulcer
and gastro-esophageal reflux can produce
hypomagnesaemia, too (31-34).
Renal function also influences significantly
magnesium metabolism. Kidneys filtrate
approximately 2.4 g/day of Mg, but most of it is
reabsorbed and only 5% is normally excreted in
urine. Diuretics can affect the level of
magnesium; loop and thiazide diuretics decrease
magnesium level, due to an increased urinary
excretion, while K+ sparing diuretics (amiloride
and spironolactone) augment it, due to an
increased renal reabsorption (35).
Diabetes mellitus can secondarily produce a
magnesium deficit by increasing the urinary
losses of magnesium (36, 37).
Older people also represent a population category
with an increased risk for inadequate levels of
magnesium, due to a reduction of intestinal
absorption and an increased renal excretion as
compared to younger population (38).
Furthermore, thelong-term use of medicationin
many aged patients interferes with magnesium
homeostasis (39).
Alcoholism reduces the plasma level of
magnesium through mechanisms that involves
both a decrease in intestinal absorption due to
pancreatitis and hepatic steatorrhea increased
Magnesium supplementation in top athletes - effects and recommendations
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urinary excretion due to a renal dysfunction.
Other possible mechanisms are secondary hyper-
aldosteronism caused by a hepatic dysfunction,
phosphorus and Vitamin D deficiency,
ketoacidosis etc (40).
As we will show further on, top athletes also
represent a population category predisposed to
magnesium deficiency due to increased urinary
and sudorific losses, and in case of heavyweight
disciplines, due to a decreased dietary intake.
Medical conditions associated with magnesium
deficiency. The symptoms of an early magnesium
deficiency are nausea, vomiting, fatigue,
headache, insomnia, confusion, irritability, muscle
weakness, while an advanced hypomagnesaemia
produces muscle cramps, paresthesia, cardiac
arrhythmia and coronary spasm. A very low level
of magnesium generates severe hypocalcaemia
and hypokalaemia that can be corrected only
through simultaneous administration of
magnesium (3, 4).
A few scientific studies published in the early
1980s supported a possible involvement of
magnesium deficiency in coronary spasm, due to
an effect on vessel smooth muscles (41). Many
subsequent studies have found significant
correlations between inadequate levels of
magnesium and various cardiovascular
pathological conditions such as high blood
pressure, ischemic heart disease and arrhythmia
(42-46). An epidemiological study that followed
the evolution of 12000 subjects over a period of
19 years showed an inverse relationship between
magnesium plasma concentration and mortality
rate produced by ischemic vascular diseases, data
suggesting that the subjects with the highest level
of plasmatic magnesium had a 30% lower risk of
developing heart disease (47).
Hypomagnesaemia has also been linked to
diabetes mellitus due to the role that magnesium
plays in maintaining glycaemia and diminishing
resistance to insulin (48-50). Although American
Diabetes Association considers that there are no
convincing proves to include magnesium in the
treatment of diabetes mellitus (51), many studies
have demonstrated that magnesium had a positive
effect on decreasing glycaemia in diabetics (50-
53).
Bronchial asthma has also been correlated with
inadequate levels of magnesium (54, 55) and a
couple of recent studies supported the positive
effect of Mg supplementation on bronchial
asthma, due to a decrease of bronchial mucosa
sensitivity in children (56, 57). Magnesium has
been proposed for prophylaxis of migraine crisis,
the positive effects being due to its involvement in
the vasoconstriction/vasodilatation processes and
release of neurotransmitters (58- 60).
The use of magnesium in treatment of depression
is still uncertain, but a low level of magnesium
has been associated with a low level of serotonin
(61, 62).
The role of Magnesium in athletic performance
Magnesium effect on energy production.
Magnesium has been one of the most used
supplements for enhancing athletic performance
(63). Many studies supported the role of
magnesium in athletic performance and showed
that magnesium increased the physical endurance
(64, 65) and improved the force indices and
muscle metabolism in athletes that had a rich diet
in magnesium or received magnesium
supplements (66).
Magnesium’s pivotal role in both anaerobic and
aerobic energy production, particularly in the
metabolism of adenosine triphosphate (ATP), the
―energy currency‖ of the body. The US
researchers concluded that low dietary magnesium
impairs function during exercise. The mechanisms
behind this effect are unclear, but it seems likely
that a magnesium shortfall can cause a partial
uncoupling of the respiratory chain, increasing the
amount of oxygen required to maintain ATP
production. There is also evidence that a
magnesium shortfall boosts the energy cost, and
hence oxygen use of exercise because it reduces
the efficiency during exercise of muscle
relaxation, which accounts for an important
fraction of total energy needs during an activity
like cycling (67). One study of male athletes
supplemented with 390 mgs of magnesium per
day for 25 days resulted in an increased peak
oxygen uptake and total work output during work
capacity tests (68); in another, on sub-maximal
work, supplemental magnesium elicited
reductions in heart rate, ventilation, oxygen
uptake and carbon dioxide production (69); in a
third, physically active students, supplemented
with 8 mgs of magnesium per kilo of body weight
per day, experienced significant increases in
endurance performance and decreased oxygen
consumption during standardized, sub-maximal
exercise (70).
As a result of some studies performed on gerbils,
the authors noticed that, when compared to
Magnesium supplementation in top athletes - effects and recommendations
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control a group, the group of animals that received
parenterally a solution of magnesium sulphate had
an increased length of physical performance and
also experienced increased levels of glycaemia
and decreased levels of lactate production during
exercise, effects that were attributed to
magnesium (71, 72).
A recent study on the use of magnesium in 1,453
adults demonstrated that higher serum (blood)
magnesium levels were associated with better
muscle integrity and function. This included grip
strength, lower-leg muscle power, knee extension
torque and ankle extension strength. These results
highlight the importance of magnesium for
improving muscle function and performance (73).
An earlier study showed that a magnesium
supplementation of 8 mg/kg associated to a
strength training at 3 times per week produced a
significantly larger increase in strength compared
to the control group that followed the same
training protocol, but without magnesium
supplementation. The authors concluded that the
result was due to the role that magnesium plays in
protein synthesis at the level of ribosomes (74).
An increase of strength indices can be due to the
stimulation of testosterone secretion that was
induced by physical training.
A 2011 study showed that a dose of magnesium of
10mg/kg produced a greater increase of
testosterone level in a group of tae kwon do
athletes, when compared to the control group that
didn’t receive the supplement. At the end of the
study, the authors concluded that magnesium
administration produced an increased level of
testosterone both in sedentary and trained
subjects, but the maximal increase was noticed
when magnesium supplementation was associated
with training (75).
However, other studies carried out on physically
active people with 'normal' serum magnesium and
muscle magnesium concentrations have found no
functional or performance improvements
associated with supplementation (76, 77).
On the evidence available so far, the scientific
consensus is that extra magnesium can enhance
performance when (as is all too often the case)
magnesium intakes fall below optimum levels.
But in subjects already consuming magnesium at
or above this optimum level, there is little hard
evidence to suggest that taking more confers extra
benefits.
The negative influence that magnesium depletion
has it on athletic performance can also be
explained by its effect on body composition. In
this respect, we mention the fact that a group of
Japanese researchers claimed that there is a corre-
elation between magnesium level and body fat
percent, reporting that increased body mass
indices had a statistically significant association to
low level of magnesium (78). In fact, a few
authors stated that a deficit of magnesium is
involved in pathogenic mechanisms of the
Metabolic Syndrome, characterized by the triad of
obesity, diabetes mellitus and hyper-
cholesterolemia, through a pro-inflammatory
effect, but this effect manifests itself only when
magnesium daily intake is below 10% of normal.
Although a moderate deficit of magnesium does
not initiate an inflammatory process, it has an
aggravating effect, especially when a
simultaneous oxidative stress is present (79).
Many studies have found correlations between the
deficit of magnesium and the C reactive protein
level, a marker of inflammation (80, 81).
Magnesium effect on postexercise recovery. An
inadequate level of magnesium can affect the
recovery after exercise and the process of a
normal adaptation to effort.
A hyperactivity of the sympathetic system,
induced by a magnesium deficit, produces an
increased release of norepinephrine and cortisol,
which represents a defective adaptation to
physical exercise that normally needs a strong
vagal tonus.
A study published in 2009 by Kazuto Omiya et al.
concluded that the abnormal exercise tolerance
associated with chronic insomnia is caused by a
hypersensitivity of cardiac rhythm to sympathetic
system stimulation, which appears as a result of a
decreased intracellular magnesium (78).Other
authors also claimed that an optimal level of
magnesium in the body is correlated with a
reduction in sympathetic system activity, low
stress level, good relaxation and better sleep (82).
Although it does not support the idea of a positive
effect of magnesium supplements on athletic
performance, a 2013 study reported a decreased
postexercise blood pressure, both in anaerobic and
aerobic exercise (83).
Furthermore, the link between magnesium
deficiency and a low sensitivity to insulin
suggests a defective replenishment of glycogen
stores in hypomagnesaemia and, through this
mechanism, an inadequate postexercise recovery
in athletes that present this disequilibrium.
Magnesium is necessary for normal muscular
contraction and relaxation. Low magnesium levels
are associated with an increased incidence of
Magnesium supplementation in top athletes - effects and recommendations
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2487
muscle cramps, which can often be reversed with
the addition of magnesium supplements. In one
research trial, swimmers taking magnesium
supplements during their training and
competitions found an 86% reduction in muscle
cramps. The reductions occurred after only three
days of supplementation (73).
Magnesium deficiencies in athletes. Even athletes,
who might be expected to take greater care with
their diets, are not immune from magnesium
deficiency; for example, studies carried out in
1986/87 revealed that gymnasts, footballers and
basketball players were consuming only around
70% of the RDA (84, 85), while female runners
fared even worse, with reported intakes as low as
59% of the RDA (86).
Some authors claim that the positive results of
magnesium supplementation on athletic
performance a reduce till a correction of
magnesium deficit that characterizes top athletes
and less to a magnesium effect per se (65).
There are a couple of scientific studies that claim
that the decrease of magnesium is a metabolic
modification induced by a sustained physical
training. An analysis performed in Israel on
metabolic effects of an intense training carried out
over a period of 6 months, showed that the study
subjects presented modifications of more
metabolic parameters, the decrease of magnesium
serum concentration being considered a primary
modification. It’s worth noticing the that the level
of magnesium didn’t change immediately after the
race, but only 72 hours later and remained
reduced over a long period of time, which varied
between 18 days and 3 months (87).
In their analysis regarding the relationship
between magnesium and physical exercise,
published in 2006, Nielsen and Lukaski warned
that physical exercise induces a redistribution of
magnesium in the body to accommodate increased
metabolic needs. Urinary and sweat losses
increase the requirements of magnesium in
athletes who train strenuously by more than 10-
20%.Dietary intake of magnesium in general
population is considered insufficient for these
athletes. In addition, the athletes that participate in
heavyweight categories (e.g., weightlifting,
boxing, etc.,) but also the female gymnasts, whose
performance require a low body weight, are even
more predisposed to magnesium deficiency, due
to a low intake caused by a caloric restriction
(65).
Magnesium supplementation may produce
improvement of athletic performance by
correcting the low status of magnesium in
athletes, which is associated with an increased
demand of oxygen for the same effort and a
decreased exercise endurance. The same authors
consider that in athletes the risk of
hypovitaminoses, especially for fat soluble
vitamins, is much smaller than the risk of mineral
deficiency (88).
Bohl and Volpe, in their analysis concerning
magnesium involvement in physical exercise,
published in 2002, also showed that the dietary
reference intakes for magnesium, in amount of
310-420 mg/day, are insufficient for those who
participate in physical training and enumerated a
couple of studies that claimed that magnesium
improves athletic performance (89).
On the other hand, regarding the direct effect of
magnesium on athletic performance, a recent
study (2014) has showed that magnesium
supplementation produced an increase of
performance indices in volleyball players, even in
those athletes who hadn’t had low levels of
magnesium (90).
Magnesium deficiency and sudden death risk in
athletes. Of paramount importance regarding the
predisposition of top athletes to inadequate levels
of magnesium is the association of
hypomagnesaemia with an increased risk of
sudden death by favouring arrhythmias (91). It is
well known that this risk is higher in top athletes
than in general population (92). Stendig and
Lindberg stated thatsudden death in athletes
during physical exercise is linked to a persistent
deficit of magnesium (93). Endurance running,
due to excessive sweat losses, can induce a severe
deficiency of magnesium towards the end of the
race, increasing significantly the risk of a serious
arrhythmia (94).
Testing For Magnesium Status
Our body contains approximately 25 g of Mg out
of which 50-60% lies in bones, 27% in
musculature, 19% in other soft tissues and less
than 1% in plasma (95). Intracellular Mg is mostly
bound by chelators, such as ca ATP, ADP,
proteins, DNA, RNA and citrate. Physiological
concentrations range between 0.75 and
0.95mmol/l (96), a blood value below 0.75
mmol/l being considered hypomagnesaemia (97).
Since only 0.3% of the total Mg is present in
serum, magnesium serum concentration is
considered a poor indicator of Mg status. There
have been proposed many methods to investigate
the level of Mg in the body, such as measuring its
Magnesium supplementation in top athletes - effects and recommendations
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concentration in saliva and urine, Mg load
tolerance tests, etc., but none was considered
satisfactory (98). Most experts agreed that a
correlation between clinical manifestations and
lab values could be the best way to diagnose
hypomagnesaemia (99, 100).
Total blood magnesium (TMg) is the most widely
used assay, but this has the disadvantage of
including complex and protein-bound magnesium,
whereas it's the ionic portion that's physiologically
active. This test is also insensitive to the
movements of magnesium that occur within the
body as a result of exercise. However, the recent
introduction of ion-selective electrode (ISE)
technology now enables scientists to measure
ionic magnesium directly, and this is considered
one of the best methods. But even then it's not all
plain-sailing, since ionic magnesium levels tend to
fluctuate significantly according to the time of
day, with higher values recorded in the morning
and lower values in the evening. This circadian
magnesium rhythm is believed to be linked to
changes in physical activity levels through the
day, but the whole subject of 'intra-body'
magnesium fluctuations remains poorly
understood.
Nevertheless, the best results seem to be obtained
when ionic magnesium is sampled from fasting,
non-exercised subjects first thing in the morning
(101).
Magnesium Supplementation
Oral supplementation. IOM (Institute of
Medicine) recommendations regarding the
amount of Magnesium that can supplement the
dietary intake for healthy persons are presented in
table II (19). These recommendations were made
in 1996 and they should be updated since current
dietary intake, due to an intensive agricultural
production and an increased processing of food,
contains increasingly smaller amounts of this
element, which is essential for the normal
functioning of the human body.
Although oral supplementation of Mg is possible,
the processes of remineralisation and
replenishment of intracellular and extracellular
Mg take time and are influenced by many factors.
An inversely proportional relationship has been
described between magnesium intake and its rate
of absorption, which varied between 65% (in case
of a low intake of magnesium) and 11% (high
ingestion). When a high dose of magnesium is
administered, there is another factor that interferes
with Mg absorption, namely an accelerated
intestinal transit, due to an increased osmolarity
and stimulation of peristalsis (102). In addition,
concomitant administration of other mineral
supplements, such as zinc or calcium, can
negatively intestinal absorption rate of Mg.
The inexpensive oral supplements of magnesium
generally contains magnesium oxide, which is
poorly absorbed (4%). Magnesium citrate is much
better absorbed (50%), but is not so cheap. Out of
a daily intake of 300-400 mg elemental Mg, only
an amount of 12-16 mg can be used (the ionized
form).
A few studies showed that soluble preparations
are generally better absorbed and magnesium
aspartate, citrate, lactate and chloride have a
superior bioavailability compared to magnesium
oxide and sulphate (103-106).
Table II. Tolerable upper intake levels (ULs) for supplemental Magnesium (19)
Age
Male
Female
Pregnant
Lactating
Birth to 12 months
None established
None established
1–3 years
65 mg
65 mg
4–8 years
110 mg
110 mg
9–18 years
350 mg
350 mg
350 mg
350 mg
19+ years
350 mg
350 mg
350 mg
350 mg
Institute of Medicine (IOM). Food and Nutrition Board. Dietary Reference Intakes: Calcium, Phosphorus,
Magnesium, Vitamin D and Fluorideexternal link icon. Washington, DC: National Academy Press, 1997.
Magnesium supplementation in top athletes - effects and recommendations
Adriana Sarah Nica & all
Medicina Sportiva
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Topical Supplementation
Topical or transdermal administration of
magnesium is an interesting alternative to oral
route, considering the many interferences in the
absorption of magnesium oral supplements.
Transdermal magnesium is applied topically,
using either magnesium lotions or magnesium
bath salts.
The local effect on mucosae and skin is well
documented. There have been some studies that
showed the positive effects of nebulized
magnesium sulphate on bronchial asthma (107)
and on skin cells proliferation and differentiation
(108).
In fact, some of the benefits of Dead Sea bath
salts are attributed not to the high content of salt,
but to magnesium itself, the prevalent cation of
Dead Sea water (109).
Comparative studies regarding the effects of a
solution whose salinity was similar to that of
Dead Sea water, showed cleared benefits over a
normal saline solution, both in the treatment of
ENT conditions (such as chronic sinusitis) (110)
and rheumatoid arthritis (111).
The hypothesis of topical supplementation of
magnesium, although appealing, faces a
challenge: transdermal diffusion of magnesium or
its salts. Unfortunately, there are few studies in
scientific literature concerning transdermal
absorption of magnesium. We are of the opinion
that the benefits obtained in the treatment of
rheumatoid arthritis, using solutions with a high
content of magnesium, represents a strong
argument that magnesium effectively crosses the
skin barrier.
In an earlier study (1977), a couple of authors
verified the transdermal absorption of a
Magnesium Sulphate solution, of various
concentrations, applied on skin for 8 hours. The
results showed that the transdermal absorption of
magnesium increased linearly with solution
concentration and skin surface area (112).
More recently, Dr R.H. Waring et al., from the
University of Birmingham, School of Biosciences,
have published an online study regarding
transdermal absorption of magnesium after daily
baths with Epsom Salt (1% solution of
Magnesium sulphate).
Each daily bath lasted for 12 minutes, over a
period of 7 days. Plasmatic concentrations of
magnesium were determined before and at 2 hours
after hydrotherapy, while urinary concentration of
magnesium was measured at 24 hours post
immersion.
The results showed an increase of magnesium
plasma concentrations from 104.68 ± 20.76
ppm/ml before experiment to 114.08 ± 25.83
ppm/ml after the first bath. Plasmatic
concentration of magnesium increased
progressively over the course of treatment,
reaching 140.98 ± 17.00ppm/ml after 7 days.
The author concluded that body immersion in a
solution of magnesium sulphate caused an
increase in plasmatic concentration of
magnesium. The renal excretion of magnesium
increased significantly after the first day, from an
initial value of 81 ± 44.26 ppm/ml to 198.93 ±
97.52 ppm/m at 24 hours after the first bath. The
greatest increases of urinary excretion of
magnesium were recorded in those subjects who
presented the smallest increases of plasmatic
magnesium, and the author hypothesized that in
these subjects magnesium ions that crossed the
skin barrier were excreted, because the plasmatic
level of magnesium had already been optimal.
However, urinary excretion of magnesium
decreased over the course of 7 days, so that at the
end of the 7th day it reached values similar to
those recorded at the beginning of the treatment
(118.43 ± 51.95), although the plasma level
increased, implying that after an extended
application of transdermal magnesium, this
mineral accumulates in the body.
The authors recommended a protocol of 2-3 baths
a week, in a solution of 1% MgSO4 (that is
600mg in 60 l water), for a maximal benefit of
general population.
The study concluded that magnesium sulphate
(Epsom salt) baths are an easy and certain method
to increase magnesium level in the body (113).
A pilot study published by Watkins K and Josling
PD, initially in European Journal for Nutraceutical
Research, in April 2010, and then in ―The
nutrition Practitioner‖, called ―A pilot study to
determine the impact of transdermal magnesium
treatment on serum levels and whole body Ca-Mg
ratio‖ also asserts that magnesium effectively
crosses the skin barrier.
The authors showed that transdermal application
of a 31% magnesium chloride formulation could
alter serum magnesium levels and whole body
calcium/magnesium ratios.
After 12 weeks’ treatment 89% of subjects
increased their cellular magnesium levels by
59.7% on the average. Similar results using oral
supplementation were noticed only after 9-24
months (114).
Magnesium supplementation in top athletes - effects and recommendations
Adriana Sarah Nica & all
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An aqueous solution of magnesium chloride, also
known as ―magnesium oil‖ is used as a massage
lotion for treating headache and muscle cramps,
and certain authors claim that the absorption of
this solution is good enough to be used as a
treatment for magnesium deficiency
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Corresponding author
Adela Caramoci
Department of Sports Medicine
University of Medicine and Pharmacy Carol
Davila
Bucharest, Romania
E-mail: adelaapostol@yahoo.com
Received: December 10, 2014
Accepted: February 25, 2015
