16 February 2021
By Jack Coxall

What is magnesium?

Magnesium plays a vital role in keeping the human body functioning as it should. It is a key micronutrient involved in at least 800 biochemical reactions, including protein synthesis, testosterone production, insulin sensitivity, calcium absorption and the regulation of the sympathetic nervous system. Furthermore, it aids in the metabolism of vitamin D and may help treat the inflammation brought on by intense exercise. Strenuous exercise may increase the loss of magnesium through sweat and urine by as much as 20%, meaning a magnesium rich diet is of particular importance for athletes.

What does it do?

Protein Synthesis

Protein synthesis relies on numerous critical enzymes, most of which have magnesium as a cofactor (a non-protein chemical compound that is required for the protein’s biological activity). To date, around 3,750 human proteins have been discovered to incorporate magnesium into their structure. Magnesium plays a vital role in protein synthesis as it enables enzyme function in the body. Protein is used for most structural components and metabolic functions in the body, meaning if you don’t have sufficient magnesium to effectively synthesise them, the consequences can be far reaching.

Muscle Contractions and Calcium Balance

The body uses magnesium to stimulate muscle contractions and deliver oxygen to muscles while they’re working. Another mineral that plays a role in muscle contractions is calcium. Calcium is typically an exciatory cofactor (meaning it only enters the cell when it is needed for something specific eg a muscle contraction). After this function is complete, magnesium helps to pump calcium out of the cell. Insufficient magnesium may mean the cell in question is unable to flush out the calcium. When this happens it can become damaged or, in extreme cases, even die. Muscle cramps may be an acute indicator of a calcium imbalance, and therefore a deficiency in magnesium.

Inflammation Treatment

A deficiency in Magnesium has been shown to lead to increased inflammation in the body, affecting blood vessels, cardiovascular, and intestinal tissues. While the exact process by which magnesium decreases inflammation is unknown, it is considered an anti-inflammatory agent due to the fact that magnesium levels are usually inversely correlated to markers of inflammation. A recent study examined the effects of magnesium in treating inflammation in rugby players pre and post competition. It found that the group supplied with magnesium supplementation showed significantly lower inflammation markers than the control group (who were not supplied with magnesium).

Heart Health

As well as aiding in athletic recovery, it’s role as an anti-inflammatory agent in the cardiovascular system means magnesium plays an important role in maintaining a healthy heart. It acts as a natural vasodilatador (meaning it helps to open blood vessels) and anticoagulant (meaning it helps prevent blood clots). Adequate intake is inversely related to arterial calcification (the hardening of arteries) as its aforementioned role in ‘pumping out’ calcium keeps calcium dissolved in the blood. Deficiencies can lead to an increase in blood pressure as well as the constriction of coronary arteries, which decreases the flow of oxygen and nutrients to the heart. Magnesium’s role in muscle contractions also contributes to keeping heart rhythms steady.

Testosterone Bioavailability

Magnesium has been shown to have a positive association with total testosterone in men. This is because magnesium increases the bioavailability of testosterone. During the aging process (or as a result of insufficient dietary protein) sex hormone binding globulin (SHBG) concentrations increae. These globulins bind with testosterone, which makes it unavailable for the body to use. However, testosterone prefers to bind to magnesium, rather than SHBG, which increases the amount of testosterone available for the body to utilise. A 2011 study measured the impact of magnesium on testosterone levels, when combined with physical exercise. The study examined 3 groups. Group 1 were sedentary men who took a magnesium supplement, Group 2 were tae kwon do athletes who took the same supplement, Group 3 were tae kwon do athletes who received no supplementation. The study found Group 2 had the greatest increases in testosterone levels, followed by Group 3, then Group 1. While the biggest increases came for Group 2 (around 24%) even the sedentary group saw an increase of 15%.

Brain Function & Depression

Magnesium plays a role in regulating a key receptor in the brain that supports memory and learning. This is due to magnesium’s role in the activity of enzymes in brain cells that control memory functions. Furthermore, the maintenance of the plasticity of synapses (the ability of synapses to strengthen or weaken over time) is dependent on magnesium content in cerebrospinal fluid. This is important because synaptic plasticity controls how effectively neurons are able to communicate with each other and send signals through the body.

Magnesium also has a role in the release of chemicals from the brain, such as serotonin which regulates mood and can help promote a feeling of calm and optimism. This means it can play a role in treating mild to moderate depression in adults.

Sleep & Stress- Sympathetic Nervous System

Adequate levels of magnesium help calm the sympathetic nervous system. It helps stabilise the membranes of nerves cells and regulate mineral concentrations used for nerve transmissions. It’s also essential for the metabolism of cortisol which is released as part of your body’s stress response. If cortisol stays in your bloodstream longer than it’s needed it has a catabolic, inflammatory effect meaning it degrades muscles as well as damaging cells and DNA. Without magnesium, your body struggles to perform the actions needed to be able to relax. This may lead to anxiety, stress or panic attacks. Furthermore, the production of melatonin (the hormone that controls sleep and wake cycles) is reliant on magnesium.

Bone Strength

Calcium is vital for bone strength. However, without enough magnesium, calcium can’t perform its functions within the body. Magnesium activates cellular enzyme activity, which allows the body to convert vitamin D into its active form. This then helps with calcium absorption and bone building. Magnesium also stimulates the production of calcitonin- a hormone that maintains bone structure and draws calcium from the blood and soft tissues to be transferred back into the bones. The parathyroid hormone, which breaks bone down, is also suppressed by magnesium.

Insulin Sensitivity

Magnesium plays a key role in the maintenance of healthy blood sugar levels and improves insulin sensitivity. Low magnesium levels decrease insulin sensitivity as it helps insulin to bind with cell receptors. It also increases the expression of molecules that transfer glucose into cells so that it may be used for energy or stored as glycogen. When blood glucose and insulin levels are high, the kidneys struggle to retain magnesium. This leads to an increased magnesium deficiency and potentially a progression into diabetes.


Ideally, maintaining an optimal level of magnesium will result from a diet consisting of foods rich in the mineral, such as:

  • Dark green vegetables (spinach, broccoli, kale, collard greens, swiss chard)
  • Fish (halibut, salmon, mackerel, tuna, pollock)
  • Nuts (cashews, peanuts, almonds, brazil nuts)
  • Seeds (pumpkin seeds, sunflower seeds, flaxseeds)
  • Legumes (black beans, edamame, kidney beans)
  • Avocados
  • Bananas
  • Raisins

How can you tell if you’re deficient?

If you’re low on magnesium for an extended period of time, you may develop a magnesium deficiency. However, this is rare. Symptoms of magnesium deficiency include:

  • Poor appetite
  • Nausea (sick to your stomach) and vomiting
  • Sleepiness
  • Weakness

In extreme cases, you may also experience muscle spasms and tremors.

While a deficiency is rare, there are certain conditions that may put you at a higher risk. Gastrointestinal diseases like IBS or colitis impact your ability to absorb dietary magnesium. Hyperthyroidism, high intensity athletic activity or high stress will also increase the demand for magnesium while type 2 diabetes can result in an increased amount of magnesium being excreted through the kidneys.

You can take a test to measure your levels of magnesium. However, only 0.3% of your magnesium is stored in your blood, meaning a typical blood serum test won’t give you the full picture. Accurately assessing magnesium levels would require a red blood cell test. An optimal measurement would be between 5.6 and 6.8mg/dL.

Should you supplement?

If you’re eating a healthy, balanced diet it’s highly unlikely you’ll suffer from a magnesium deficiency (unless you fall into one of the high risk groups identified above). There have been studies to suggest that magnesium can increase physical performance in athletes, due in part to its impact on testosterone bioavailability, inflammation and muscle cramp prevention. However, there are a number of steps you can take to increase your magnesium intake without resorting to supplements.

  • Reduce intake of coffee, alcohol and soft drinks. These drinks can increase magnesium wastage and reduce its absorption.
  • Sodium competes with magnesium for ion channels (protein molecules that span across the cell membrane allowing the passage of ions from one side of the membrane to the other). Therefore, reducing sodium consumption will positively impact magnesium levels.
  • Reduce consumption of processed food, as heavy processing is likely to reduce food’s mineral content.
  • Soak beans and grains before cooking to reduce phytic acid, which interferes with magnesium absorption in the gut.
  • Steam raw greens like spinach and chard to reduce oxalic acid, which also interferes with magnesium absorption.
  • Opt for organic greens were possible. Artificial fertilisers are often poor in magnesium, leading to reduced magnesium content in the food they produce.

If you do choose to supplement, pay attention to the contents. Ensure you opt for a magnesium that is bound with one of the following: citrate, malate, glycinate, threonate, taurate, fumarate, or orotate. These are more easily absorbed and are less likely to negatively impact bowel function than cheaper options like magnesium oxidate.


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