Many fail to meet their daily magnesium requirement; boost your intake with dark green leafy vegetables, nuts & legumes – even dark chocolate! 

Biological relevance and mechanisms of action

Magnesium is the second most abundant mineral in the body and plays an essential role in the musculoskeletal and nervous systems, as well as mediating over 300 biochemical reactions and metabolic processes by acting as an enzyme co-factor.

The total body magnesium content in adults is approximately 24 g, 99% of which is found within the cells with just 1% circulating in the blood. The majority is stored in bone (contributing to the density and strength of the skeleton), muscle (contributing to muscle contractions) and soft tissue, especially in organs that are the most metabolically active such as the brain, heart, liver and kidneys, reflecting magnesium’s critical role in energy production. Bone tissue is by far the largest magnesium store and functions as an easily accessible reservoir when magnesium intake is low. Prolonged inadequate magnesium intake can result in bones being ‘leached’ of magnesium reserves, and is a risk factor for osteoporosis. 

Magnesium acts as a cofactor for a number of enzymes involved in energy production. ATP (the main energy currency used for all metabolic processes), for example, cannot function unless it is joined to magnesium. As such, low magnesium status is often related to conditions where fatigue is a key symptom. 

Deficiency of magnesium is linked to various disorders including cardiovascular (e.g. heart failure, arrhythmia, heart attack, stroke and hypertension), musculoskeletal (muscle spasms & cramps, osteoporosis), gastrointestinal (constipation) and central nervous system (e.g. insomnia, anxiety, depression, chronic fatigue syndrome and impaired cognitive function) disorders.  


Magnesium homeostasis is controlled by the intestines, bones and kidneys. Of the total dietary magnesium consumed, only about 24–76% is absorbed in the gut and the rest is eliminated in the faeces. Many factors are known to influence magnesium absorption however, irrespective of magnesium source, with studies showing that certain foods can restrict the absorption of magnesium in the human body. For example, high protein diets can decrease magnesium absorption; tannins present in tea can bind magnesium making it unavailable for absorption. Presence of oxalates in certain vegetables (e.g. rhubarb, spinach and chard) and phytates in cereals and legumes can also reduce the absorption of magnesium by up to 60%. In contrast, consumption of fermentable dietary fibre, such as fructooligosaccharides found in bananas, onions, chicory root, garlic, asparagus and leeks can enhance magnesium absorption by 10-25%.

Health benefits

The health benefits of magnesium are well established and supplementation can both provide relief from active symptoms and support systems to prevent chronic illness developing or worsening.

Magnesium contributes to: 

  • a reduction of tiredness and fatigue 
  • electrolyte balance
  • normal energy yielding metabolism
  • normal functioning of the nervous system
  • normal muscle function
  • normal protein synthesis
  • normal psychological function
  • the maintenance of normal bones and teeth
  • the process of cell division 

Sources of the nutrient

Magnesium is widely distributed in foods of plant and animal origin, with tap & bottled water making a significant contribution to dietary intake of magnesium (higher in hard water than soft water). As chlorophyll is the magnesium chelate of porphyrin, green leafy vegetables are particularly rich in magnesium. Vegetables, grains, and nuts generally have a higher magnesium content than animal products. Given that the UK population fails to achieve the 5-a-day in terms of vegetable intake it is likely (as seen in USA where intake of magnesium <50% requirements) that intake is insufficient to sustain adequate requirements.

Magnesium is found in high quantities in dark chocolate, avocados, nuts (especially almonds, cashews and brazil nuts), seeds (e.g. flax, pumpkin and chia seeds), whole grains & pseudo grains (e.g. buckwheat and quinoa), legumes, tofu, leafy greens and even fatty fish. 

Refining and processing of food can deplete magnesium content by up to 85%, and cooking (especially boiling) also results in significant loss of magnesium. As the intake of refined foods increases (as seen in developed countries) magnesium deficiency will most likely evolve into a more common disorder. 

It is noteworthy that insufficiency in additional nutrients will also have an impact on magnesium levels. For example, the synergistic relationship that exists between vitamin D and magnesium also sheds light on the low status of magnesium that is common in the UK. Vitamin D at physiological doses enhances magnesium absorption, and adequate levels of magnesium are essential for the absorption and metabolism of vitamin D to calcitriol. Thus suboptimal intake of vitamin D (known to be common in the UK) or magnesium will have a number of potential health consequences. 

Why supplement?

Despite being one of the most prevalent minerals in the body, magnesium deficiency is becoming surprisingly common. Evidence from the latest nutrition and diet survey (2012-2014) highlights that a substantial proportion of adults aged 19 years and over have intakes below the Lower Reference Nutrient Intake. Consistently low intake or poor absorption due to renal failure, liver disease or alcoholism can lead to deficiency which causes symptoms such as muscle weakness, fatigue, secondary calcium deficiency and neurological symptoms.

While certain groups are considered more at risk of magnesium insufficiency, such as those with conditions mentioned above, as well as menstruating women and the older generation, most people are not consuming adequate magnesium and could benefit from supplementing. 

Whilst choosing the best quality supplements is paramount for effectiveness, it is also important to acknowledge factors affecting an individual’s magnesium levels. Those who base their diets on refined and processed carbohydrates are at a higher risk of insufficiency/deficiency; this is becoming worryingly common and can have a significant negative impact on our health. 

In addition, common drugs that interfere with magnesium absorption (such as H2 antihistamines and proton pump inhibitors) or enhance excretion either via the GI tract (such as laxatives) or by renal loss (such as diuretics) are all known to contribute to the low magnesium status of the UK population. Individuals with certain pre-existing health conditions, such as diabetes, osteoporosis, heart disease, GI disorders & renal disease are prone to a poor magnesium status. 

Magnesium supplementation – factors to consider

With rates of magnesium deficiency already high and on the increase, and the benefits of magnesium supplements well established, it is clearly a priority to choose the most effective magnesium product for use in clinical practice, in order to have the greatest impact on improved health.

When considering what makes a superior magnesium, the following factors should be considered because they have a direct influence on the efficacy of a magnesium supplement. 

Forms of magnesium – the importance of solubility and chelates in improving magnesium bioavailability


Organic soluble complexes

Organic soluble salts

Inorganic soluble salts

Inorganic insoluble salts


Bisglycinate, taurate

Citrate, lactate, gluconate

Chloride, sulphate

Oxide, carbonate, hydroxide






If the magnesium compound used is insoluble, it is poorly absorbed. Magnesium from magnesium salts (such as oxide, sulfate, hydroxide, chloride or citrate) is absorbed only after the magnesium is liberated from its salt.  Solubility therefore refers to the ease with which a magnesium salt releases its magnesium ion and is one of the most influential factors affecting bioavailability. 

Insoluble magnesiums (oxide, carbonate & hydroxide) require an acid environment to break the bond between the salt and the magnesium. In contrast, soluble salts such as citrate do not require the presence of acid to release their magnesium ion.   Thus, citrate has an immediate advantage over the insoluble salts, because insoluble salts will remain unabsorbable unless the pH is favourable enough to break this bond.  Once magnesium has been freed from its carrier, the majority will be absorbed via paracellular ion channels, (where magnesium moves between the tight junctions of the GI tract). This is important when we consider that clients with high levels of stress often have low levels of stomach acid. 

Forms of magnesium – the importance of solubility and chelates in improving magnesium bioavailability

In contrast to magnesium salts, magnesium ‘chelates’, such as glycinate and taurinate, bypass ion channels and are instead absorbed in the same way that dietary amino acids are absorbed from the gut.  The bond that joins magnesium to an amino acid is incredibly strong and works in favour of magnesium absorption because as the amino acid crosses the cell membrane, it pulls magnesium in after itself, giving magnesium a ‘free ride’.  The benefit of the chelate doesn’t end there.  When considering the absorption of a magnesium salt, when the magnesium ion is liberated from the salt, unless it is immediately absorbed by an ion channel it remains extremely vulnerable, attracting water and becoming too big to be absorbed, or forming bonds with compounds found in food (oxalates and phytates) and becoming insoluble. 

Choosing between a magnesium salt and a magnesium chelate

There are benefits to both magnesium salts and magnesium chelates in terms of bioavailability. By combining magnesium citrate, as a soluble salt, and magnesium bisglycinate and taurate, as chelates, a magnesium complex benefits from four unopposing absorption pathways. 

Furthermore, these three forms of magnesium create a favourable acidic environment to protect free magnesium ions from interacting with food or water that would, under normal circumstances, interfere with magnesium uptake, thus enhancing the absorption of free ions.


Magnesium comes in one of three forms: as a blend, a buffered or a fully reacted supplement. Both blends and buffered magnesium supplements contain magnesium oxide, even if not declared on the label. So, while a product may have a label claim of magnesium citrate, magnesium bisglycinate or magnesium taurate, unless it clearly states that the product contains fully-reacted magnesium, much of your elemental claim will come from magnesium oxide. 

Fully reacted magnesium is superior to buffered magnesium supplements or blends which contain magnesium oxide.

Magnesium oxide is widespread in the supplement industry – cheaper supplements use pure magnesium oxide while others use a combination of magnesium oxide and other forms of magnesium, even if not declared on the label. Magnesium oxide, with its higher elemental fraction, provides an easy marketing tool to boost label claims. To be considered bioaccessible (a form which the body can use), magnesium has to be absorbed and retained, and only fully-reacted magnesium can be considered to be truly bioaccessible. While fully-reacted magnesium has a lower elemental magnesium content than the blended and buffered forms, the body can utilise the magnesium delivered by fully-reacted products more effectively. This is because the bioaccessibility of fully-reacted magnesium boosts magnesium bioavailability which in turn leads to a bioactive, effective magnesium product. Most manufacturers choose to use blends or buffered forms of magnesium rather than fully-reacted forms because they are cheaper and can lead the consumer to believe they are getting better value for money. But if your magnesium isn't bioaccessible, then it is literally like throwing money down the drain. For example, the laxative side effect experienced with unabsorbable magnesium oxide (due to it having extremely low bioaccessibility) occurs as a result of water moving out of the cells that line the gut in an attempt to dilute the high concentration of unabsorbable magnesium, which is essentially then just flushed out of the body!

If you are taking a magnesium product and experiencing gastrointestinal upset, the chances are it will be a blended product with high oxide content. In contrast, fully-reacted magnesium forms complexes and is directly bound to the carrier via a manufacturing process, therefore containing no magnesium oxide, and the total elemental magnesium is 100% soluble magnesium citrate. 

How can I tell if my magnesium contains magnesium oxide if it states it is magnesium citrate?

A magnesium citrate product containing magnesium oxide will contain a blend of magnesium oxide and citric acid. No reaction takes place to join the magnesium oxide with the citric acid (unlike when fully-reacted magnesium citrate product is produced where the oxide is removed and replaced entirely with citrate). The function of citric acid (citrate) in the blended formulation is to lower the pH in the stomach in an attempt to help release the magnesium ion from the oxide carrier and facilitate its uptake. It also ‘boosts’ the elemental magnesium and while the elemental magnesium is from magnesium oxide, the product will be labeled as magnesium citrate. The key to differentiating it from a fully-reacted product will be the amount of magnesium per capsule or tablet. This will always be suspiciously high, with blended magnesium citrates often claiming close to or even 100% of the nutrient reference value per single capsule/tablet (NRV = 375mg). 

In contrast, a buffered magnesium citrate product will combine some fully-reacted magnesium citrate topped up with magnesium oxide to boost the elemental magnesium label claim (because while fully-reacted is superior, the amount of magnesium delivered can be low). A buffered product can deliver around 30% magnesium. Again, the product will be labeled as magnesium citrate. While the amount of magnesium per capsule or tablet will be less than blended magnesium, it will still deliver an unknown fraction of insoluble magnesium oxide. While buffered magnesium products are superior to blended magnesium products, only fully-reacted magnesium products can guarantee no hidden magnesium oxide.

Indeed, fully-reacted magnesium products do have lower elemental magnesium content, but the manufacturer will be transparent in communicating the amount of magnesium to the consumer and will clearly label their product as the superior fully-reacted form. This gives the consumer confidence in the product's efficacy because while the amount of magnesium may be lower, it is in a form that can be absorbed and retained by the body. Given that raising magnesium status is the key objective to supplementation, it makes sense to choose a fully-reacted product over a blend or buffered product. In addition, supplements should always declare the elemental fraction (the amount of magnesium per dose) rather than just the bulk (the amount of raw material used) because the bulk amount will not provide information on the amount of elemental magnesium per dose. If only the bulk material is declared (e.g. 'magnesium citrate' rather than magnesium [as/from citrate]), it may be reasonable to assume that the manufacturer does not wish to be entirely transparent in communicating the type, the form or amount of magnesium to the consumer.

Our Triple Magnesium Complex of citrate, bisglycinate, and taurate delivers 262mg 100% fully-reacted magnesium (70% NRV) per 2 tablets, and is superior to buffered magnesium supplements or blends that contain magnesium oxide. The bioaccessibility of fully-reacted magnesium boosts magnesium bioavailability which in turn leads to a bioactive, effective magnesium product. Our customers can be confident that they are getting effective forms of magnesium with little risk of unpleasant side effects.

The importance of split dosing

The majority of ingested magnesium is absorbed in the small intestine, and it is well established that taking small, regular amounts of magnesium is favourable to taking one large dose (which saturates the gut’s normal absorption capacity). 


With this in mind, compared with formulations that overwhelm the body’s ability to absorb and retain magnesium, a supplement that offers a slow, sustained exposure to magnesium throughout the day will help optimise magnesium uptake more efficiently. 

Studies have shown that the absorption of magnesium from a low elemental dose can be as high as 65%, but that when the dose exceeds 250mg, the relative absorption is reduced to as little as 21%. It therefore makes sense to optimise the absorption and retention of magnesium by splitting our Triple Magnesium Complex daily dose into 2 smaller doses (131mg each). This carefully considered dose focuses on retention rather than excretion. As previously discussed, the body carefully regulates plasma magnesium levels, with excess intake above the body’s capacity to handle, simply resulting in magnesium loss. Our ethos is to focus on the efficacy of delivery, using three of the most absorbable and synergistic ‘carriers’ to target multiple, unopposed uptake pathways with the emphasis on split-dosing to optimise both absorption and retention. 

When considering magnesium supplementation, an individual’s current magnesium status is the primary influencer of how much magnesium is absorbed and retained. Therefore, higher doses may become appropriate when you have results to confirm blood levels are low, as absorption will be higher and less will be excreted. 

Additional carrier benefits

Many select a magnesium supplement based on the added benefits of the carrier. By combining three forms, clients can benefit from every feature, negating the need for several supplements. 

In addition to glycine’s health benefits, the two glycine molecules in magnesium bisglycinate occupy the reactive sites of magnesium, preventing it from forming insoluble complexes with phytates & oxalates, thereby helping to increase uptake and retention of magnesium.  

Taurine comes with its own health assets, but in addition, taurine & glycine act as pH buffers, creating an optimal environment to aid magnesium uptake from citrate, allowing citrate to then feed into the citric acid (Krebs) energy production cycle. 

Shop by nutrient > magnesium to view the Igennus range of supplements.


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