Magnesium: A Mineral Key To Health

Miraculous magnesium: unlock the power of this master mineral.

Magnesium: A Mineral Key To Health photo

How does magnesium benefit health?

Magnesium is the fourth most abundant mineral in our body, along with calcium, potassium and phosphorus. Magnesium plays a wide range of roles, such as regulating blood pressure, blood sugar levels, heart and neuron functioning. In this article, we will discuss magnesium’s role in health and the effect of deficiency, recommended intake levels, sources of magnesium in the diet and supplementation options.

Functions of Magnesium in the body

The body contains about 24g of magnesium, of which 99% is stored (60% in bone, 20% in muscles, 19% in soft tissue) with the remaining 1% being found in red blood cells and serum. Magnesium levels are strictly controlled by the intestine, bone and kidneys under hormonal control. Serum levels are maintained even when dietary intake is low or when excessive amounts are excreted, drawing magnesium from soft tissue and bone stores to restore serum levels.1,2

Magnesium plays many different roles in the body:

  • Acting as a co-factor in more than 300 enzyme reactions
  • Promoting growth via the synthesis of DNA, RNA and proteins
  • Key to energy production and carbohydrate metabolism
  • Involved in muscle contraction and relaxation
  • Involved in bone health and metabolism
  • Maintaining normal cardiac function
  • Maintaining normal neurological function
  • Maintaining normal organ function (liver, skin, lung, ear, kidney)
  • Acting as a vasodilator and supporting blood pressure control
  • Acting as inhibitor of body processes similar to a drug, e.g. calcium blocker
  • Acting as an antioxidant and anti-inflammatory agent
  • Playing a role in immunity such as immune cell development
  • Involved in nerve signalling and hormone activation

Recommended daily intake of magnesium

The UK recommended daily intake values for magnesium are:3

  • Children aged 1-3 85mg/day
  • Children aged 4-6 120mg/day
  • Children aged 7-10 200mg/day
  • Childrene aged 11-14 280mg/day
  • Children aged 15-18 300mg/day
  • Men aged 19+ 300mg/day
  • Women aged 19+ 270mg/day

Athletes, pregnant and individuals with diagnosed conditions (eg. infections, Type 2 Diabetes Mellitus) may require increased intakes. 4–6

Food sources of magnesium

Magnesium is found in a wide range of foods:7 seeds (pumpkin, sunflower), legumes (chickpeas, beans, lentils), nuts (cashew, almonds, Brazil nuts, pistachio), peanuts, whole grain cereals/products (oats, millet, buckwheat, wholewheat), cocoa, quinoa, dark chocolate, avocado, dried apricots, blackberries and hard/mineral water.

Factors affecting magnesium bioavailability

The majority of ingested magnesium is absorbed via the small intestine. This is normally 30-40% of available magnesium. Factors which impact magnesium bioavailability and absorption are:1

  • Increased age and gastrointestinal dysfunction can deplete magnesium absorption.
  • Eating unrefined/processed foods, such as whole grains, nuts, seed, legumes, increases magnesium bioavailability due to their fermentable fibre content (i.e. inulin, oligosaccharides, resistant starch)
  • Foods rich in phytates (e.g. nuts, seeds, legumes) and oxalates (e.g. rhubarb, spinach) can inhibit magnesium absorption. However, these foods have high magnesium content which helps to compensate the lower absorption.
  • Food rich in phosphorus reduces the amount of magnesium absorbed. Examples are phosphoric acid in soft drinks, dietary phosphates in processed meats, dairy and cheese products.
  • Aluminium found in many products (cookware, deodorants, prescription and over-the-counter drugs, food products) can lead to a reduction in the bioavailability and retention of magnesium in the body.
  • High intakes of zinc can lead to reduced absorption of magnesium.
  • Alcohol and coffee can decrease magnesium bioavailability, as can some prescribed drugs such as diuretics, insulin and digitalis.
  • Magnesium works in balance with calcium in the body. A diet rich in calcium can lead to reduced absorption and retention of magnesium. Likewise, a diet lacking in magnesium can lead to hypocalcaemia.8
  • Vitamin D is required for magnesium absorption and vice versa! A lack of Vitamin D can lead to loss of magnesium from the body. A lack of magnesium can lead to vitamin D associated problems such as low immune function.9
  • Vitamin B6 works alongside magnesium in many enzyme processes. A lack of vitamin B6 can lead to loss of magnesium from the body.10

Assessing for magnesium deficiency

Magnesium status is difficult to assess due to the tight control of serum levels by the body. If magnesium levels rise, excess is excreted in the urine. Urinary assessment may indicate if excretion is within normal parameters, although this is further affected by age and gender, hormones and drugs. If serum magnesium falls, and dietary or supplemental provision is inadequate, the body draws magnesium from bone stores to maintain serum levels. There are methods to assess magnesium status that are heavily invasive, expensive and are used for research purposes only. Magnesium deficiency is always accompanied by secondary imbalances, such as decreased potassium and increased sodium.1

Magnesium Supplementation options and dosage

Studies have shown that people consuming a typical Western diet, the elderly and those with gastrointestinal conditions (e.g. Crohn’s, ulcerative colitis) are more likely to be magnesium deficient. A Western diet more often contains processed foods, demineralised water and foods grown in magnesium-depleted soils.11

There are numerous supplemental forms of magnesium, for example inorganic salts (eg. Magnesium oxide, chloride, sulphate) and organic compounds (eg. Magnesium citrate, malate, pidolate, taurate). The amount of magnesium taken up depends on the initial magnesium status of the individual, ie. those with low status, uptake will be high, whereas for those with higher status, uptake will be less. Generally, soluble forms (e.g. magnesium aspartate, citrate, lactate and chloride) are more readily absorbed. Better absorption can be achieved through smaller multiple doses across the day. Unabsorbed magnesium salts (such as with magnesium oxide) can cause diarrhoea due to their osmotic effect and stimulation of gastric motility. The supplement label will declare the amount of elemental magnesium provided not the total amount of the compound.1,12

Supplementing with 200mg of chelated magnesium (citrate, lactate) is likely to be safe, adequate and sufficient over a period of 20-40 weeks to re-establish magnesium homeostasis (1). An upper limit of 240mg/day (which does not include dietary intake from foods) is recommended by EFSA.13

Contra-indications: Magnesium supplementation is not recommended if you are taking diuretics, heart medications or antibiotics. If you have diabetes, gastrointestinal conditions, heart or kidney disease, you should consult your GP before taking magnesium supplements.

Effects of excess magnesium supplementation

Although the body maintains magnesium levels by increasing excretion via the kidneys, toxicity can occur from excessively high supplemental intake, drugs or other sources. Initially, excess magnesium supplement intake results in diarrhoea, nausea, vomiting and abdominal cramps. The supplement forms most associated with diarrhoea symptoms are magnesium carbonate, chloride, gluconate and oxide.12

Toxicity symptoms following sustained excessive (ie. 10 times the recommended) supplemental intake and may manifest as:1

  • Muscle weakness
  • Low blood pressure
  • Loss of deep tendon reflexes
  • Issues with the electrical signals in the heart
  • Respiratory paralysis
  • Cardiac arrest!

Health conditions linked to magnesium deficiency

Diabetes, metabolic syndrome and insulin resistance

Magnesium plays a fundamental role in carbohydrate metabolism and energy production. This is through its involvement with the enzyme reactions that take place in cell mitochondria (the body’s battery cells) and in the liver. Magnesium supports glucose tolerance, and deficiency leads to disrupted carbohydrate metabolism. Likewise, uncontrolled blood sugars, insulin resistance and imbalanced lipid profiles contribute to magnesium depletion. Supplementation with magnesium in these individuals may improve their health status.5,14–18

Hypertension and Cardiovascular diseases

Magnesium is involved in blood pressure control through its action on calcium levels. Magnesium and calcium work together to support healthy arteries and blood vessels. Magnesium deficiency has been shown to be associated with an aged-related increase in blood pressure.19 However, magnesium supplementation may not address hypertension as effectively as a high-magnesium diet which is usually also high in potassium and low in sodium, both of which contribute to normal blood pressure.

Magnesium deficiency has been shown to be associated with cardiovascular disease. Deficiency can lead to altered lipid metabolism promoting atherosclerosis. Magnesium acts as an antioxidant, mopping up “free radicals” produced during oxidative stress and prevents platelet aggregation and clot formation. It also helps maintain cardiac rhythm and rate. Overall, magnesium is effective in reducing the risk of cardiovascular diseases. 6,14,15,20,21

Neurological diseases and cognitive decline

Magnesium deficiency has been shown to be associated with a range of neurological conditions such as migraine, stroke, degenerative neurological conditions, insomnia, anxiety and depression.22–24 Magnesium impacts the action of neurotransmitters (e.g. serotonin, glutamate). It increases energy production in mitochondria (where energy is made within each cell) and is required when cells are stressed. Magnesium controls calcium in cells so as to prevent excessive or insufficient neurotransmitter action. Magnesium also acts an antioxidant and has anti-inflammatory properties in the brain.1,2

Magnesium levels in the brain affect several biochemical processes involved in cognitive function, including cell membrane stability and integrity, neurotransmitter behaviour and calcium level control. There is a potential effect of increased magnesium intake slowing cognitive decline, although more research is needed in this area.25

Osteoporosis and muscle health

Bone stores the majority of magnesium found in the body. Osteoporosis occurs when there is less bone being made compared to the rate at which bone is being broken down, leading to reduced bone mineral density, a more porous structure that is increasingly susceptible to fracture. Magnesium promotes bone formation. Magnesium deficiency is associated with reduced osteocalcin; a protein required for bone formation. Magnesium’s anti-inflammatory action reduces the rate at which bone is broken down, improving bone density and strength. Magnesium is necessary for vitamin D synthesis, transport and activation in the body, including vitamin D’s role in bone homeostasis. However, vitamin D is also required for intestinal magnesium absorption!21,26,27

Magnesium deficiency has been related to poor muscle performance, muscle weakness, pain and night cramps. Magnesium is essential for oxygen uptake, energy production and the balance of sodium and potassium in skeletal muscles. Deficiency also increases oxidative stress in muscles and potentially alters muscle cell metabolism. Magnesium regulates calcium activity in normal muscle contraction and relaxation and reduces the likelihood of cramps.28,29


A number of studies have indicated that magnesium deficiency increases the risk of certain cancers (e.g. breast, liver and colorectal). Magnesium is involved in DNA repair, gene maintenance and the regulation of a cell’s life from formation to elimination. Magnesium deficiency can lead to disruption of these processes, promoting cell mutations, tumour formation and cancer diagnosis.1,25

Respiratory diseases

Magnesium works alongside calcium to support normal lung function. Magnesium deficiency leads to bronchial contraction and spasm. It exerts an antioxidant and anti-inflammatory effect in the lungs. Magnesium deficiency has been observed in asthmatic individuals and improved magnesium status reduces breathlessness and improves pulmonary function. Magnesium has more recently been found to have associations with severity and duration of Covid-19 infection. 2,25,30

Immune function and health

Magnesium is intricately involved in immune responses, controlling immune cell development, homeostasis and activation. Magnesium is involved in the elimination of unwanted cells and thymus health, in addition to being necessary for vitamin D synthesis, transport and activation. Magnesium deficiency may lead to increased susceptibility to bacterial and fungal infection. It reduces inflammation and oxidative damage in cells by regulating immune cells such as lymphocytes and leukocytes. 9,19,30

Key Takeaways

In summary, magnesium is found throughout the body and plays many roles in health. Magnesium levels are closely controlled via uptake from the dietary and supplemental provision in the intestines, withdrawal from bone deposits and excretion via the kidneys making assessment of magnesium status difficult. There are a number of health conditions associated with magnesium deficiency. Some of these may be avoided or the risk reduced by consuming magnesium-rich foods within a balanced diet.

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