Magnesium

Magnesium is one of the twelve minerals designated as essential nutrients and its importance is hard to overstate.  Magnesium plays an essential role in almost all biochemical and metabolic processes within the cell, as one of the microelements that regulate the "on" and "off" functions in the neural circuits of your body.  In an intricate dance, magnesium works in concert with calcium to regulate electrical impulses in the cell. Calcium increases excitation and the transfer of signal from one neuron to another – leading to a contraction, while magnesium inhibits it, temporarily shutting down this transfer-leading to relaxation.  The mag and calcium phase are constantly changing in a homeostatic fashion.

As a result, magnesium plays a central role in processes such as protein synthesis, energy production, muscle contraction and relaxation, cardiac activity, and bone health, while also offering anti-inflammatory and antioxidant benefits (Laires & Monteiro, 2008; Barbagallo, 2010; Barbagallo et al, 2021). As such, magnesium is recognized for its critical role in athletic performance and overall health (Volpe, 2015).

Mag is the fourth most abundant mineral in the human body, and nearly 60% of it lies within bone tissue, 40% in muscles and about 1% in the blood stream (Rondanelli et al, 2021).  (For the sake of brevity, we will refer to it as Mag in this writeup).

D, K and Mag
Mag has a mutually dependent relationship with vitamin D, and together with vitamin K, they form an effective cocktail for bone health and healing.

Vitamin D is a fat-soluble vitamin that regulates calcium absorption and is vital for the development and maintenance of a healthy skeleton. Among athletes, bone fractures can impair function and training.  Minimizing the bone healing time, while maximizing bone strength of the fracture site during healing are important outcomes. Early or accelerated fracture healing is highly desirable.  Vitamin D ensures that there is sufficient calcium available to heal bone fractures and it accelerates the initial mineralization around a fracture (Ray, 2014). In the case of injury, vitamin D supplements can reduce bone loss due its effect on bone mineralization (Hayes et al, 1996; Beaudart et al, 2014).

Before vitamin D can perform its vital functions, it must be converted to a biologically active form, first in the liver and then in the kidneys.  The enzymes that do this conversion need Mag to function properly.  Otherwise, vitamin D will remain in its inactive form, making it all but useless (Heaney, 2008; Reddy & Sivakumar, 1974; Uwitonze & Razzaque, 2018; Erem et al, 2019; Saponaro et al, 2020; Underland et al, 2020).  If you are not taking sufficient Mag, then vitamin D is inactive. 

Magnesium also boosts vitamin D activity by supporting the parathyroid hormone to stimulate the kidneys to convert vitamin D to its active form (Risco & Traba, 1992; Rosanoff et al, 2016; Khundmiri et al, 2016).  Insufficient Mag can cause a reduction in parathyroid hormone levels leading to a decrease in active vitamin D levels which would impair bone health (Al Alawi et al, 2018), even to the point of creating rickets (Swaminathan, 2003; Ozsoylu & Hanioğlu, 1977; Anast, 1967; Uwitonze & Razzaque, 2018). Rickets is a softening or weakening of bones caused by severe and prolonged vitamin D deficiency.  Research has shown that vitamin D intake alone failed to treat rickets, but adding Mag supported vitamin D activation and helped resolve the condition (Dai et al, 2018).

Mag enables vitamin D to bind to a carrier protein that transports it though the blood (Deng et al, 2013; Rosanoff et al, 2016) and it helps activate the receptors needed for cells to use vitamin D. A deficiency of Mag decreases the number of vitamin D receptors in cells, limiting the vitamin’s effects (Reddy & Edwards, 2019).  Mag also regulates 24-hydroxylase, an enzyme that helps inactivate vitamin D when there’s an excess supply (Dai et al, 2018; Deng et al, 2013). 

A high consumption of Mag reduces the risks of vitamin D deficiency in the general population (Deng et al, 2013; Vázquez-Lorente, et al, 2020). One study claimed that a significant increase in serum 25(OH)D was achieved only when vitamin D supplementation was given with Mag.  Another study found that it took intakes of both vitamin D and Mag to increase the serum level of 25(OH)D (Fuss et al, 1989)

The magnesium-vitamin D partnership isn’t a one-way street.  Vitamin D can enhance intestinal absorption of Mag, allowing the mineral to be more efficiently used by the body for skeletal mineralization (Dusso, 2014; Lanske & Razzaque, 2007; Uwitonze & Razzaque, 2018; Erem et al, 2019)

However, keep in mind that the intestinal absorption of Mag declines with advancing age, which contributes to Mag deficits in the aging population.  And with aging, often there are chronic diseases and their treatment with multiple medications, with both the disease and the medications potentially contributing to Mag deficits (Barbagallo et al, 2021; Dominguez et al, 2020).

Vitamin K is an essential part of the biochemistry that binds calcium to bone, and it is required to activate two proteins, osteocalcin, and matrix Gla protein.  Osteocalcin is a calcium-binding protein produced by osteoblasts in bone tissue which promotes bone mineralization (Knapen et al, 2013).   MGP is another calcium-binding protein that inhibits the calcification of arteries and cartilage, delivering calcium from these areas to the bone and facilitating healthy bone formation. Adequate levels of K2 (menaquinones) facilitate bone health (Van Ballegooijen et al, 2017; Akbari et al, 2018; Qureshi, 2019).

Magnesium deficiencies lead to fragile bones.  However, when vitamin K2 (MK4) was available, it inhibited the bone resorption caused by the Mag insufficiency, restoring bone remodeling and improving bone health (Amizuka et al, 2005).  This is an important finding, as it indicates the presence of vitamin K is an important factor in bone health and strength.

There is a wealth of research on the importance of vitamin K for fracture healing and its beneficial effect on all collagen tissues, particularly bone tissue. Vitamin K is so important that when there is an injury, it is sequestered to the site of fracture, reducing the circulating levels of vitamin K in fracture patients. The time taken for the circulating levels of vitamin K to return to normal appears to be influenced by the severity of the fracture, as K will remain sequestered at the injury site while needed (Hodges et al, 1993).

The Grassroots Health study showed that folks who take both supplemental magnesium and vitamin K2 have a higher vitamin D level than those taking either supplemental magnesium or vitamin K2 or neither. (Grassrootshealth.net/blog, 2020).

Together the combination cocktail of vitamin D, vitamin K, and Mag offer a multi-faceted approach to bone health, with fractures healing in 70% of the typical time.  This is widely known in the research field but not so much in the clinical field.

Performance
Mag has been deemed essential in a wide variety of cellular activities related to athletic performance and has been studied as an ergogenic aid for athletes (Dominguez et al, 1992; Razzaque, 2018). Many studies support the role of magnesium in athletic performance showing that magnesium increased physical endurance (Wang et al, 2014; Nielsen & Lukaski, 2006). 

Six young healthy males ages 21 to 25 years of age who received potassium-magnesium-aspartate supplements showed a 50% increase in the capacity for continuous physical exercise for 90 minutes versus men given a placebo (Ahlborg, 1968).

An early study found a correlation between blood levels of magnesium and maximal oxygen consumption. 44 healthy male university athletes and 20 untrained men were underwent maximal treadmill exercise testing.   Plasma mag levels were significantly correlated with maximal oxygen consumption (VO2Max) among the athletes.  The authors suggested that ionic magnesium may facilitate oxygen delivery to working muscle in trained subjects (Lukaski et al, 1983). 

A study of twenty-two competitive swimmers, ages 9.5 to 12.9, (11 males, 7 females) compared to a control group found a significant positive correlation between blood levels of magnesium and VO2max in the male swimmers (Conn et al, 1988).

A study of 20 female and 12 male recreationally active students were supplemented with 314 mg/day Mag for four weeks.  After consumption of either placebo or Mag supplementation, subjects completed an exercise trial which involved performing contractions on an isometric leg dynamometer until exhaustion. After another four weeks supplementation subjects returned for a second isometric leg trial to exhaustion, and they showed significant increases in endurance performance and decreased oxygen consumption during standardized, sub-maximal exercise (Brilla & Gunther, 1995).

In a double-blind randomized study, 23 competitive triathletes competing in an event consisting of a 500-meter swim, a 20-km bicycle race, and a 5-km run were studied after 4-week supplementation with placebo or 17 mmol/d Mg orotate. The Mag-orotate group showed significantly better times in all three events of swimming, cycling, and running, compared to the control group.  Serum glucose concentration increased 87% during the test in the control group and 118% in the Mg-orotate group, while serum insulin increased 39% in the controls and decreased 65% in the Mg-orotate group. Venous partial pressure increased 126% during the test in the controls and increased 208% in the Mg-orotate group. Venous partial pressure after the bicycle race decreased 66% (significantly) in the Mg-orotate group compared with 74% in the controls. Those who received the Mag showed altered glucose utilization and a reduced stress response without affecting competitive potential (Golf, 1998).

Thirteen recreationally active athletes were given 500mg of Mag daily over a five-week intervention period, compared to a placebo group who took no supplements.  Measurements were taken of blood pressure, serum levels of magnesium and sports performance including a 10K running time trial.  Statistically significant differences were observed in the running time trial, blood pressure readings and in heart rate (HR) recorded at 10-minute intervals during the running trial following Mg2+ supplementation. Following the Mg2+ intervention there was increased speed with an average decrease in 10K completion time of exactly one minute (1.77%) (P=0.001) (Pitkin, 2014).

Twenty elite soccer players took either 5500 mg of Mag creatine chelate in 4 capsules per day, which was 0.07g/kg/d or a placebo for sixteen weeks. At the beginning and end of the study, they participated in the RAST field test (Running-Based Anaerobic Sprint Test).  The soccer players who took the Mag showed significantly better results in Total Time, Average Power, and Max Power, and in the first 35 m sprint and the sixth 35 m sprint (Zajac et al, 2020).

Energy Production
During exercise, carbohydrates are broken down sequentially into glucose to provide energy and support during muscle movement. As glucose metabolism and glycolysis for energy production is dependent on cellular magnesium status, insufficient magnesium supply in the body can impair energy production (Garfinkel & Garfinkel, 1985;  Zhang et al, 2017)

Magnesium plays a vital role in the production of ATP (adenosine triphosphate), the primary source of energy for cells. During exercise, your body needs to produce large amounts of ATP to fuel your muscles, and Mag helps facilitate this process by raising the availability of ATP (Ebel & Gunther, 1980; Aikawa, 1981; Lukaski, 2000; Lee, 2017).

Moderately trained adults were given either placebo or magnesium supplements (250 mg Mg/d as magnesium picolinate) and showed an improved cardiorespiratory function during a 30-min submaximal exercise test.  The findings suggested a beneficial effect of Mag supplementation on muscle metabolism and work efficiency (Ripari et al, 1989)

A study of male athletes supplemented with 390 mg of Mag per day for 25 days, resulted in an increased peak oxygen uptake and total work output during work capacity tests (Rude, 1993). 

A study which examined the effects of dietary magnesium restriction on biochemical responses during submaximal exercise found that low levels of magnesium may disrupt the body’s ability to efficiently use energy stores.10 postmenopausal women, 45-71 years old, not receiving hormone replacement therapy was investigated. They found that red blood cell (RBC) count, Mag concentration, Mag retention and skeletal muscle Mag concentration were decreased when dietary Mag was restricted. Peak oxygen uptake (VO2max), total and cumulative net oxygen uptake and peak heart rate were increased by up to 1%. These findings indicate that dietary Mag depletion results in increased energy needs and adversely affects cardiopulmonary function during submaximal exercise (Lukaski & Nielsen, 2002).

Mag and Muscles
Both calcium and magnesium regulate muscle contraction.  Calcium leads muscles to contract, while magnesium leads the muscles to relax (Shrimanker & Bhattarai, 2013). However, under conditions of magnesium deficiency, even minimal amounts of calcium can result in hypercontractility, marked by muscle cramps and spasms (de Baaij et al, 2015).  This can manifest itself during sleep, i.e. calf cramps.

Low magnesium levels are associated with an increased incidence of 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 (McDonald & Keen, 1988).

Tip:  Magnesium malate appears to be the most bowel tolerated (least discomfort).

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 (Cinar et al, 2011). This same study showed that the 10mg/kg dose of magnesium produced a greater increase in testosterone level in a group of Tae kwon do athletes, compared to a control group who didn’t receive the supplement.  Both groups showed an increase, but the maximal increase of testosterone was in the group associated with training (Cinar et al, 2011). 

There are cardiovascular consequences of magnesium deficiency.  The presence of magnesium antagonizes calcium’s work for muscle cell contraction.  However, when magnesium is deficient, there is more smooth muscle contraction and vasocontraction, which have been associated with changes in blood pressure, vascular reactivity, and cardiac rhythm disorders that could result in altered blood flow to the muscle (Rayssiguier et al, 1990).

Tip:  Magnesium intake as Mag should be between 600 and 1000 mg/day.

Strength and Power
Twenty-six subjects 18 to 30 years of age with no strength training in the last 6 months were randomly divided into two groups: a group supplemented with magnesium oxide and a control group given a placebo. The total amount of magnesium ingested by the placebo group was 246.5 mg/day compared with the supplemented group who averaged 507.4 mg/day. Subjects then engaged in a 7-week strength training program. The supplemented group showed significantly greater strength increases than the control group (26% vs. 11%, respectively). The authors postulated that magnesium may play a role in protein synthesis and suboptimal magnesium intakes may affect the increased muscle protein density normally associated with strength training (Brilla & Haley, 1992).

A randomized, controlled trial found that magnesium supplementation in healthy elderly women induced a significant improvement in strength and short physical performance. The most significant outcomes were observed in subjects whose diets were lower in magnesium at the beginning (Veronese et al, 2014).  However, a recent study has shown that magnesium supplementation produced an increase of performance indices in volleyball players, even in those athletes who were not magnesium-deficient (Setaro et al, 2014).

Thirteen subjects were recruited from recreational running, cycling and triathlete clubs, and were allocated randomly to the Acute intervention group and a Chronic intervention group. The Acute group received 300 mg/d of magnesium citrate once a week, while the Chronic group received citrate 4 days a week.  The participants engaged in a 40K time trial, followed by a bench press at 80% to exhaustion while assessing the effect on strength performance and vascular responses. The current study showed a positive effect with Acute Mg²⁺ supplementation in relation to net strength and force gains with bench press.  The mag supplementation had no effect on physical performance when serum concentrations are within the normal range. There were greater reductions in blood pressure in the Acute group (Kass & Poeira, 2015).

Evidence is growing that Mag may be an important element to maintain muscle mass and power. A cross-sectional study assessed the associations between dietary Mag intake, skeletal muscle mass, power and strength, and CRP in women, aged 18 to 79 years.  They found that higher dietary Mag intake was significantly associated with measures of inflammation, leg explosive power, and muscle mass.  They found a 24.2% greater leg explosive power with the highest intake of Mag compared with the lowest (Welch, et al, 2016).

Anti-Inflammatory
The practice of sport at a high level (elite competition) can provoke changes in the immune system which can impact performance and endurance levels (Keats et al, 1988; Nieman et al, 1997). 

A study examined the effect of Mag supplementation on muscle damage markers.  Twelve elite male basketball plays in the Spanish Professional Basketball League and a control group (CG) comprising twelve university students who practiced regularly recreational basketball and competed in minor university leagues participated in the study. The athletes were supplemented with 400 mg/day of Mag lactate. Blood samples were taken four times during the season, each separated by eight weeks: T1: October, T2: December, T3: March, and T4: April. Serum Mg concentrations showed a significant decrease in T3 (Mar) with respect to T1(Oct) and T2(Dec) . At the end of the study, serum Mag concentration was significantly higher at T4 (April) than at T3 (March). Levels of muscle damage parameters remained the same during the entire season (P > 0.05), indicating that the muscles parameters were sustained and did not decline. In conclusion, these results suggest that the supplementation with Mg during the season of competition may prevent associated tissue damage (Córdova Alvarez et al, 1996).

Magnesium plays a significant role in the immunoregulation of the body. It is critical to natural and adaptive immunity, partly by influencing the activity of vitamin D metabolites (Touyz, 2004; Tam et al, 2003).  Studies have consistently shown that a low magnesium status correlates with increased low-grade systemic inflammation, as evidenced by elevated levels of proinflammatory markers such as TNF-α, IL-1β, and C-reactive protein (CRP) and a reduction in the levels of anti-inflammatory cytokines (King et al, 2006; Barbagallo & Dominguez, 2014; Veronese et al, 2022). Low Mag levels also cause endothelial dysfunction and inflammatory syndrome (Maier et al, 2021). Histamine is a key component in an inflammatory response, and magnesium deficiency can affect histamine secretion (Ashique et al, 2023).

In a recent study looking at whether magnesium supplementation influences muscle damage in professional cyclists, participants competing in a 21-day cycling race were split into one of two groups—one that received 400 milligrams of magnesium during the 3-week competition, and one that did not. At the end of the race, the athletes that supplemented with magnesium had significantly higher blood-magnesium levels and less muscle damage than the ones who didn’t.  This trial suggests that having higher blood levels of magnesium during competition may be protective of muscles during vigorous exercise. (Cordova, et al, 2019).

Recovery
A double-blind study examined the effects of Mag supplementation (350 mg/day for 10 days) on college-aged male and female subjects who completed baseline and posttreatment eccentric bench press sessions, followed by performance sessions 48 hours later.   The results showed significantly reduced muscle soreness at 24, 36, and 48 hours.  They also estimated their soreness and those who received the Mag also felt better, compared to the subjects who received the placebo (Reno et al, 2021).

Lactate
Lactate (lactic acid) is a metabolite that is primarily produced by intense physical exercise. If it builds up, it can limit muscle performance and you will fatigue faster.  According to studies, magnesium appears to lower lactate levels in your blood (George & Heaton, 1978).

Female rowers who had blood levels of Mag at the low end of normal were supplemented with either 360 mg of aspartate or a placebo for 3 weeks.  Those who received the Mag had lower levels of skeletal muscle damage biomarkers after training, in comparison to the placebo group. Furthermore, it was also reported that the Mag supplementation group had lower serum lactate concentrations and 10% lower oxygen uptake when performing a submaximal performance trial, indicating that the Mag had a positive impact on sports performance (Golf et al, 1993).

30 healthy individuals, aged 18-22 years, were divided into three groups: (1) Mag supplementation group; (2) Mg supplementation plus Tae-Kwan-Do training group; and (3) only Tae-Kwan-Do training group. After a four week intervention, the results indicated that Mag supplementation improved exercise performance, measured by a 20 minute shuttle run test, by decreasing the accumulation of lactate (Cinar et al, 2006).

A recent study gave 10 mg of magnesium per/kg of body weight/ per day for four weeks to adult tae-kwon-do athletes.  There were three groups, Inactive taking Mag, Training 90-120 mins five days a week and taking Mag or Not taking Mag and training.  They found that the two groups taking magnesium showed decreased lactate levels which positively affected their performance.  The group who did not receive magnesium showed a decrease in performance. These findings show that magnesium supplements has a positive effect on performance by reducing lactate levels even in sedentary people (Cinar et al, 2007)” 

Taiwanese researchers investigated the effects of administering pre-exercise magnesium (17mg per kg of body weight) on rats that swam for 15 minutes. Prior to exercise, the blood levels of lactate, glucose and pyruvate were no different in magnesium-supplemented rats when compared with rats given no magnesium (control group). However, following the forced swimming, the lactate levels in the magnesium-supplemented rats rose 130% above pre-exercise levels compared with a 160% rise in the control group. The researchers concluded that not only did the Mag help suppress lactate production, but it also increased glucose availability and metabolism in the brain during exercise. This is important because scientists now believe that the brain and central nervous system play a large role in determining the degree of muscular fatigue we feel, higher brain glucose availability could translate into lower levels of perceived fatigue (Cheng et al, 2007).

Deficiency
Given the role of Mag in the entire body, low levels can impact everything, as no other chemical element can effectively assume its multifaceted roles. Mag deficiencies may impair athletic performance which may lead to oxidative damage (Rock et al 1995), muscle cramps (Garrison et al, 2012), immunosuppression (König et al, 1998; Laires & Monteiro, 2008), and heart arrhythmias (Lukaski, 2005; Nielsen & Lukaski, 2006; Nielsen et al, 2007).

Research indicates that athletes often have a Mag deficiency. Those undergoing active workouts and/or subjected to stress often have greater magnesium needs.  When metabolism usage is accelerated, as during exercise, the requirement for magnesium may also increase (Rayssiguier et al, 1990).  A magnesium deficiency reduces physical performance, and magnesium status may have an effect on exercise capacity (Lukaski et al, 1983; Scherr et al 2012).

Interest in magnesium deficiency and its impact on physical activity began with a study on a female tennis player who had frequent episodes of muscle spasms associated with prolonged outdoor exercise.   In the presence of otherwise normal physical, neurologic, and blood biochemical findings she had decreased serum magnesium (0.65 mmol/L; normal range: 0.8–1.2 mmol/L). The muscle spasms were resolved after a few days of oral magnesium treatment (500 mg/d) (Liu et al, 1983).

Regardless of gender, athletes participating in sports that have weight classifications, or in which the competition includes an aesthetic component, tended to consume inadequate amounts of dietary magnesium (<55% of the RDA) Magnesium intakes among male and female collegiate athletes were found to equal or exceed 66% of the DRI. Men participating in collegiate football had greater dietary magnesium intakes than did female collegiate gymnasts and basketball players (Hickson et al, 1986; Hickson et al, 1987)

Surveys of dietary intakes of athletes have shown that as many as half consumed diets less than the recommended intake of magnesium for sedentary adults (Food and Nutrition Board, 1980).  Some studies have found the estimation of magnesium intakes is at or above the recommended levels (Singh et al, 1993; Fogelholm et al, 1991), while other studies of athletes have shown that magnesium requirements are often not met by their diets (Moffatt, 1984; Singh, et al, 1998; Nuviala et al, 1999).

Magnesium intakes of 270 U.S. Navy Sea, Air, and Land (SEAL) trainees were determined from dietary intake records. Thirty-four percent of the trainees had magnesium intakes below the recommended level (Singh et al, 1989).

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, with 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 (Stendig-Lindberg et al, 1991)

Another case study involved a 17-year-old soldier who was exercising strenuously and developed severe muscle spasms and pain in his legs. A thorough physical examination showed the only abnormality was a low serum magnesium concentration (1.3 mg/ dL). An examination of his diet revealed that he had an inadequate intake of magnesium. His active lifestyle, combined with his eating habits, resulted in a negative magnesium balance and eventually a deficiency. The soldier was given intravenous infusions of 3 g of magnesium sulfate over 6 h and, the next day, given an intravenous infusion of 5 g of magnesium sulfate. Within 48 h of the second infusion, he had fewer muscle pains and the spasms had resolved. After 4 days, he was completely pain free and the spasms completely gone (Bilbey & Prabhakaran, 1996)

A study of 78 women involved in different sports (karate, handball, basketball, and running), using seven-day, weighed-food dietary reports, revealed that no group of the female athletes reached the minimum intake recommended for magnesium (Table 6) (Nuviala et al, 1999).

Bohl and Volpe (2002) in their analysis concerning magnesium involvement in physical exercise, 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.

Despite the awareness of the risk of magnesium deficiencies in athletes, research shows that it continues to be present years later.

The nutrient intake of Japanese male collegiate soccer players was followed and the data showed that mean magnesium intake was lower than the RDA for Japan (Noda et al, 2009).

In an Australian population of elite female athletes (n = 72), Calcium (22%), Iron (19%) and Magnesium (15%) intakes were identified as deficient when assessed by a food frequency questionnaire (Heaney et al, 2010)

The dietary intake of college rugby players was researched, based on food frequency questionnaires, (18 forwards and 16 backs) compared with that of 26 sedentary individuals. They found that magnesium intake was lower than the recommended intake in the rugby players compared with that in the sedentary controls. They were not consuming the proper amount of magnesium in their diets, and this is likely the case for other collegiate athletes (Imamura et al, 2022).

Reviews of the literature revealed that athletes participating in sports requiring weight control (e.g., wrestling, gymnastics) often consumed less than the FAO/WHO Recommended Daily Intake. A study of elite female gymnasts showed them to have diets that were inadequate for several vitamins and minerals, including magnesium. Analysis of two 3-day food records showed a mean magnesium intake of 201.7 mg/day, far below the recommended intake level, and 31% of the gymnasts consumed less that 50% of the recommended level (Moffatt, 1984).  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 (Nielsen & Lukaski, 2006).  Thus, a significant number of physically active people would find it beneficial to increase their intake of magnesium (Steen & McKinney, 1986; Laires et al, 2001; Lukaski, 2001; Bohl & Volpe, 2001).

Studies on athletes show the prevalence of suboptimal magnesium levels can be well above the 50-percent prevalence seen in the average adult population (Reddy & Edwards, 2019)

Pollock (et al, 2020) followed the magnesium status of elite track and field athletes for 8 years.  Athletes on the British Athletics world class performance plan undertook blood testing for Red Cell Magnesium status. They found that 22% of athletes were identified as clinically deficient (<1.19 nmol/L=2.89 mg/dL).  The average red cell magnesium concentration was 1.34 nmol/L=3.26 mg/dL (in the US a normal RBC mag level ranges from 4.2-6.8 mg/dL). Magnesium was significantly lower in female athletes and those with Black or Mixed-Race ethnicity and was higher in Throws athletes and Paralympians with Cerebral Palsy. Athletes with a history of achilles or patella tendon pain had significantly lower magnesium levels than average.  They also found that lower REMg was associated with muscle injury rate over the course of this study.

The magnesium status of athletes was evaluated via a systematic review of cross-sectional studies before April 5, 2021. Fourteen studies were included in the systematic review, involving 855 athletes and 521 control subjects.  Despite higher total dietary magnesium intake, athletes generally had lower serum magnesium concentration and higher 24-h urinary magnesium excretion, demonstrating that the magnesium requirement of athletes is higher than the untrained population (Zhang et al, 2023).

There is evidence that marginal magnesium deficiency can impair exercise performance and thereby intensify the negative consequences of strenuous exercise such as oxidative stress (Nielsen & Lukaski, 2006).  Oxidative stress is an imbalance of free radicals and antioxidants in the body which can damage cells and tissues, contributing to the development of many diseases (Zheltova et al, 2016).

Deficiency due to loss/excretion
One explanation is that athletes engaged in intense exercise may have increased losses of Mag through sweat and urine excretion (Robinson et al 1954; Nielson & Lukaski, 2006; Nuviala et al, 1999).  These losses would be compounded if exercising in a hot humid environment.  A single bout of exercise may not produce a noticeable magnesium loss, but daily training may lead to continuous depletion (Costill, 1977)

An early study found that 12% of magnesium was excreted daily through sweat. In this study, magnesium losses in sweat accounted for 4–5% of daily magnesium intake and 10–15% of total magnesium excretion (feces, urine, and sweat)  (Consolazio et al, 1963).  Another study in 1977 indicated that between 18 and 60 mg magnesium/L of sweat may be lost in such an environment, representing 5-20% of the recommended daily intake of magnesium (Costill, 1997).  Other studies have found much lower concentrations of magnesium in sweat in a hot dry environment (3.4mg/L) and under hot humid conditions (12.2mg/L) (Shirreffs & Maughan, 1997), but the amount lost is still significant in individuals performing intense exercise with a high amount of sweating.

Insufficient Intake/ increased demand.
Athletes are usually engaged in hard physical training and therefore they may have an increased demand for Mag and/or the training load may contribute to Mag loss, (Lijnen et al, 1988; Resina et al, 1995; Kato et al, 2016; Rodriguez et al, 2009; Santos et al, 2011). 

Physically active individuals often fail to consume a diet that contains adequate amounts of minerals, including magnesium, which leads to a nutrient deficiency and results in substandard training and impaired performance (Bohl & Volpe, 2002; Lukaski, 2004; Seelig, 1994).  An evaluation of the pre- and postseason dietary intake of National Collegiate Athletic Association Division I female soccer players showed they had a marginal intake of magnesium (defined as <75% of the dietary reference intake) (Clark et al, 2005).  However, magnesium intakes of athletes assessed as they ate in a training center environment exceeded the RDA (Fogelholm et al. 1992).

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 (Hickson et al, 1986; Hickson et al, 1987), while female runners fared even worse, with reported intakes as low as 59% of the RDA (Zierath et al 1986).

Regardless of sex, athletes participating in sports that require weight classifications (i.e., wrestling) or have an esthetic component included in the competition (i.e., ballet or gymnastics) tended to consume inadequate amounts of dietary magnesium, 30% to 55% of the 1989 RDA (Hickson et al, 1986; Nica et al, 2015).

Recommended Daily Allowance (RDA)
Magnesium is not synthesized by humans, consequently it needs to be regularly ingested from the diet to meet recommended intake levels.  Magnesium is present in almost all foods in varying concentrations.  It is contained in leaf vegetables, legumes and whole grains, nuts and seeds, and coffee (Rondanelli et al, 2021).

The dietary reference intake (RDI) for Mag is 420mg for males and 320 mg for females. However, standard diet in the United States contains only about 50 percent of that amount and there are calls to increase the current Upper Limit for intake (Costello et al, 2023). Net absorption of dietary magnesium in a typical diet is approximately 50% (Siener & Hess, 1995). As much as half of the total population is estimated to be consuming a magnesium-deficient diet (Workinger et al, 2018; Fiorentini et al, 2021).

Tip:  This RDA is not for athletes but was determined for people who are not necessarily physically active or training.

The intake of Mag in the diet is affected by several factors.  Food processing methods cause an enormous loss of magnesium content.  For instance, refined oils, grains, and sugar lose most of their magnesium during processing. More than 80% of the Mg is removed from the grain refining treatments (white bread contains only 15 mg/100 g).  When nuts and seeds are roasted or their oils extracted, magnesium is lost. 

The concentration of magnesium in water is highly variable, depending on its origins (Leclercq et al, 2009).  Fluoride in drinking water binds with magnesium, creating a nearly insoluble mineral compound that ends up deposited in bones, where its brittleness increases the risk of fractures.  However, if water comes from deep wells that have magnesium at their source, or from mineral-rich glacial runoff, the water can be an excellent source of magnesium. 

Cola drinks which contain phosphoric acid deplete your system of magnesium immediately.  The phosphoric acid binds the Mag and it leaves your body via urine.  Alcohol has a similar effect, acting acutely as a Mag diuretic with a vigorous increase in the urinary excretion along with other electrolytes.  Chronic intake of alcohol will deplete the body’s stores of Mag (Rivlin, 1994).

The bioavailability of Mag is affected by specific components of the diet.  Calcium, brans and seeds, additives and preservatives in processed foods, and long chain fatty acids decrease its absorption.

Cooking food reduces its bioavailability (Dilworth et al, 2007), while the presence of proteins, fructose, inulin (starch found in fruits and vegetables), root vegetables, fruit and plant sugars, and dairy products increase its bioavailability (Roth & Werner, 1979; Seelig, 1981; Coudray et al, 2003; Coudray et al, 2005). 

In addition, the quality of food generally available, grown with modern agricultural methods that favor NPK (nitrogen, phosphorus, and potassium) fertilizers create a relative magnesium deficiency in the soil.  These fertilizers bind the magnesium, making it unavailable to the crop (Chaudhary et al, 2021). 

Men consuming 355 mg (14.8 mmol)/day of magnesium were in positive magnesium balance on a low-fiber (9 g/day) diet but in negative balance on a high-fiber (59 g/day) diet (Kelsay et al, 1979).  Similar trends were observed in young women consuming 243 to 252 mg (10.0 to 10.5 mmol)/day of magnesium and receiving a lower fiber (23 g/day) versus higher fiber (39 g/day) diet (Wisker et al, 1991).

Additionally, exercise performance enhancers can leave you low in magnesium, including the caffeine, sugar and sodium in sports drinks (electrolyte replacement drinks), sports gels, and proteins bars and shakes loaded with calcium.  All of these use up Mag in the process of being metabolized.  And it can become a vicious cycle.  The more you deplete your body of magnesium, the more help you’ll need to sustain a high level of activity. If you turn to caffeine and the wrong kind of sports supplements, your magnesium levels will plummet further.  As an example, coffee halts the absorption of magnesium in your intestines (Bergman et al, 1990).

Based on the previous studies, elite athletes consumed Mg ranged from 45% to 117% of the daily recommended amount ( Knechtle et al, 2008). In a large survey, Fogelholm et al, 1991) found greater magnesium intakes among 114 male Finnish athletes than 117 age-matched male control subjects.  Similarly, dietary magnesium was greater among Nordic skiers than in their age- and sex-matched, nontraining counterparts (Fogelholm et al, 1992) This difference may be attributed to the skiers’ greater energy intake (men: 1.6 compared with 1.2 MJ/d; women: 1.2 compared with 0.9 MJ/d) and the greater nutrient density of the skiers’ diet. Regardless of activity status, dietary magnesium exceeded the recommended intakes in both studies.

Types of Magnesium
Magnesium supplements are available in a variety of formulations, including inorganic salts (e.g., chloride, sulfate, hydroxide (Maalox), carbonate) and organic compounds (e.g., citrate, malate, picolinate, taurate, glycinate, orotate, aspartate) as well as inert forms (oxide).

The most bowel tolerated and better absorbed are the chelated Mags in this order: malate, followed by orotate, picolinate, taurate and glycinate.  Of the chelated Mags, malate remains high for an extended period of time in the body.  Magnesium oxide and citrate have the lowest bioavailability (Uysal et al, 2019).

The least bowel tolerated is citrate, which is used as a prep for colonoscopies, followed by carbonate, and oxide (Ranade & Somberg, 2001).  Oxide is functionally not bioavailable, Hydroxide and carbonate require mixing with water (aka know as Mag Water or in a Mag Smoothie).

Too much Mag consumed in the diet through food ingestion does not pose a health risk in healthy individuals because the kidneys are able to eliminate excess amounts via urine (Musso, 2009).

When purchasing a supplement, always look at the label to determine the serving size, and how much mag is in the serving size.  The label will say how many milligrams of Mag, as Magnesium, per serving.  For example, magnesium malate is magnesium with a sugar attached.  Hence, some mag malate products will advertise themselves as 1360 milligrams per pill.  Be sure to look at the label to see just how much of that 1360 is actually magnesium in each pill. 

Based on experience and biochemistry, recommendations for athletes would be 600 milligrams to 1 gram per day.

Testing
Magnesium concentrations in the bloodstream are low and maintained within narrow ranges, meaning levels found in routine blood work may not accurately reflect total body content.  Magnesium is primarily intracellular, so serum levels of Mag may not reflect your actual levels.  A patient can have total magnesium deficiency but the “mag” you get back in the metabolic panel may be normal.

The best tests to measure your magnesium levels are RBC (Red Blood Cell) Magnesium, Serum Magnesium, and Serum Calcium.  The Serum Calcium test is useful as your serum magnesium and your serum calcium ratio should be 1 to 1, telling you that those two minerals are in balance in your body. (The Serum Calcium test is also known as the Total Calcium Test).

 

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