What is the Best Type of Magnesium Supplement?

Magnesium is a crucial mineral that has numerous essential functions in the body.

Since magnesium is vital for our health, supplements are a useful option for people with inadequate dietary intake of the mineral.

However, there are many different supplements on the market. Despite many claiming to be the best, not all of them are equal.

This guide examines the available magnesium supplements alongside their bioavailability, benefits, and drawbacks.

Types of Magnesium Supplement

Magnesium Supplement Tablets Inside a Giant Capsule With 'Mg' On It.

First of all, there are numerous magnesium compounds, and they all vary in their efficacy.

Some of these are organic compounds, compounds that in most cases contain a carbon-hydrogen bond. These ‘magnesium complex’ supplements are made in a lab by bonding magnesium salts with an amino acid.

On the other hand, pure magnesium salts, which are found in seawater or via mining, are inorganic compounds. In most cases, inorganic compounds do not contain a carbon-hydrogen bond.

In science, ‘organic’ and ‘inorganic’ are completely unrelated to the ‘organic’ term used in agriculture. Therefore, don’t assume “organic” is better than inorganic.

Initial studies show that whether a magnesium supplement is organic or inorganic has little to no effect on bioavailability (1, 2).

1) Magnesium Aspartate

Name: Magnesium Aspartate
Molecular Formula C4H5MgNO4
Typical Form: Capsules, powder
Type: Organic

Magnesium aspartate, otherwise known as Magnesium L-aspartate, is one of the better-rated magnesium supplements.

Research shows this compound can be quite effective.

For instance, in a randomized study, the results demonstrated that magnesium aspartate has a bioavailability of approximately 10% (3).

Although magnesium aspartate’s absorption rate is better than some forms of magnesium, it is not as good as others, and the supplement comes somewhere in the middle.

2) Magnesium Carbonate

Name: Magnesium Carbonate
Molecular Formula MgCO3
Typical Form: Powder
Type: Inorganic

Magnesium carbonate is an inorganic compound, and it can be made in a lab by mixing a natural magnesium salt with sodium bicarbonate.

This supplement often comes in the form of bulk white powder, and trials suggest that it effectively raises magnesium levels.

In one study, administration of 110 mg of magnesium carbonate increased serum levels of magnesium in 22 healthy participants (4).

Long-term studies also suggest that magnesium carbonate may potentially hold benefits for decreasing joint pain and reducing coronary artery calcification (CAC) (5, 6).

However, in a comparative study on rats with magnesium deficiency, magnesium carbonate was not as effective at increasing magnesium levels as magnesium aspartate and magnesium chloride (7).

4) Magnesium Chloride

Name: Magnesium Chloride
Molecular Formula MgCl2
Typical Form: Liquid, powder, tablets, transdermal spray
Type: Inorganic

Producers of magnesium chloride extract the mineral from salt/sea water, and several different forms of the supplement are available.

In one study on a group of type 2 diabetes patients with hypomagnesemia, 12 weeks of magnesium chloride supplementation led to “significantly higher” blood levels of magnesium (8).

Studies also suggest that magnesium chloride may have potential benefits for fibromyalgia patients and patients suffering from seizures. On this note; in an animal study, magnesium chloride reduced seizures better than magnesium aspartate (9, 10).

The bioavailability of magnesium chloride seems to be similar to magnesium citrate at around 30%, and it is much more bioavailable than magnesium oxide (11).

5) Magnesium Citrate

Name: Magnesium Citrate
Molecular Formula C6H6MGO7
Typical Form: Capsules, Liquid, Tablets
Type: Organic

Magnesium citrate is one of the most research-proven, widely available magnesium supplements, and studies show that it is both bioavailable and highly effective.

For example, recent studies have shown;

  • Magnesium citrate is significantly more bioavailable than magnesium oxide (12).
  • In a randomized, double-blind trial, magnesium citrate was found to be more bioavailable than magnesium chelate and magnesium oxide. Supplementation with magnesium citrate led to the highest average magnesium blood levels after 24 hours, and also after 60 days of daily supplementation (13).
  • Furthermore, a study investigating the gastrointestinal absorption of magnesium citrate found that the supplement had high solubility (approximately 55%) and bioavailability (around 30%) (14).

6) Magnesium Gluconate

Name: Magnesium Gluconate
Molecular Formula C12H26MgO16
Typical Form: Powder, tablets
Type: Organic

Magnesium gluconate is a combination of magnesium salt and gluconic acid.

The supplement usually comes in the form of tablets or powder, and research shows that it has one of the best levels of bioavailability.

For instance, in a study on rats with magnesium deficiency, magnesium gluconate exhibited higher bioavailability than nine other types of magnesium (including magnesium citrate and lactate, which were the second and third best performing).

Of course, we can’t automatically infer these results would be the same in humans, but there is also no reason why they shouldn’t be (15).

7) Magnesium Glycinate

Name: Magnesium Glycinate
Molecular Formula C4H8MgN2O4
Typical Form: Capsules, powder, tablets
Type: Organic

Magnesium glycinate, otherwise known as magnesium diglycinate or magnesium bisglycinate, is an organic compound created by combining magnesium salts with the non-essential amino acid glycine.

Interestingly, research shows that magnesium glycinate can be well-absorbed even in individuals with impaired magnesium absorption.

In a randomized study, researchers found that the supplement was highly bioavailable and digested in a different way to regular magnesium supplements.

It appears that magnesium glycinate absorption happens in the jejunum, which is a different part of the small intestine (16).

Some past research suggests that magnesium deficiency could be a factor in depression.

In this regard, case studies have demonstrated ‘rapid recovery’ from depression using daily supplementation with magnesium glycinate (17).

8) Magnesium Hydroxide

Name: Magnesium Hydroxide
Molecular Formula H2MgO2
Typical Form: Liquid, powder, tablets
Type: Inorganic

Magnesium hydroxide is an inorganic compound sometimes referred to by the product name ‘Milk of Magnesia.’

This supplement is typically used as an antacid or laxative.

Additionally, the magnesium in magnesium hydroxide is not absorbed, and it is not a suitable choice for increasing magnesium levels.

9) Magnesium Lactate

Name: Magnesium Lactate
Molecular Formula C6H10MgO6
Typical Form: Capsules
Type: Organic

Magnesium lactate, also called Magnesium l-Lactate, is an organic magnesium compound formed by the magnesium salt of lactic acid.

One animal study found that the supplement shares similar bioavailability to magnesium citrate, but falls behind magnesium gluconate (15).

Additionally, randomized trial in healthy adult participants showed that the magnesium has ‘reasonable bioavailability’ and can help to lower blood pressure (1819).

10) Magnesium L-threonate

Name: Magnesium L-threonate
Molecular Formula C8H14MgO10
Typical Form: Capsules, powder, tablets
Type: Organic

Magnesium L-threonate is the magnesium salt of L-threonic acid, and the supplement is much more expensive than other types of magnesium.

There are also claims that magnesium L-threonate is the most absorbable of magnesium supplements.

However, the supplement is relatively new, and there is little in the way of research to prove this claim. That said, the existing research shows potential for the supplement to improve general cognitive health.

On this note, a randomized controlled trial shows that “cognitive ability significantly improved” in older adults taking magnesium L-threonate for 12 weeks (20).

Further studies suggest that magnesium L-threonate may help to prevent synaptic loss in dementia and improve memory (21, 22).

11) Magnesium Malate

Name: Magnesium Malate
Molecular Formula C4H4MgO5
Typical Form: Capsules, tablets
Type: Organic

Magnesium malate is an organic compound formed by combining magnesium salts with malic acid.

Unfortunately, there is very little research available on magnesium malate at this point.

However, one recent study on the bioavailability of numerous magnesium supplements had a favorable finding for the compound.

In this rat study, a single 400 mg dose of magnesium malate led to higher blood levels of magnesium for a longer time than the other magnesium forms (which included magnesium citrate and sulfate) (23).

More research is necessary to judge the efficacy of magnesium malate better.

12) Magnesium Orotate

Name: Magnesium Orotate
Molecular Formula C10H6MgN4O8
Typical Form: Capsules, liquid, tablets
Type: Organic

Magnesium orotate is a supplement formed from magnesium salts and orotic acid.

However, it appears that orotate may be one of the least effective types of oral magnesium supplement.

For one thing, the compound exhibits poor water solubility, and the bioavailability is relatively unknown (24, 25).

13) Magnesium Oxide

Name: Magnesium Oxide
Molecular Formula MgO
Typical Form: Capsules, powder, tablets
Type: Inorganic

Magnesium oxide, also known as magnesia, is an inorganic magnesium salt.

Unfortunately, the bioavailability of magnesium oxide is poor, and absorption rates can be as low as 4% (26).

Due to this poor absorption, magnesium oxide is also more likely to cause gastrointestinal side effects (such as diarrhea) than other forms of magnesium (27).

There are better magnesium supplements available.

14) Magnesium Sulfate

Name: Magnesium Sulfate
Molecular Formula MgSO4
Typical Form: Capsules, powder, salt, tablets
Type: Inorganic

Magnesium sulfate, also known as Epsom salt, is an inorganic magnesium supplement.

Interestingly, in addition to oral supplements, there are claims that people can increase their magnesium levels by bathing in Epsom salt baths.

However, the research is not conclusive on this.

Some studies show that this transdermal application of magnesium sulfate leads to slight increases in magnesium levels. But these results are not clinically significant, so it is difficult to say for sure (28).

A review of the evidence on this also concluded that this method of magnesium application was “scientifically not yet proven” (29).

On the negative side, oral magnesium sulfate supplementation appears to result in only “limited” absorption. Furthermore, side effects such as diarrhea are common (30).

15) Magnesium Taurate

Name: Magnesium Taurate
Molecular Formula C4H12MgN2O6S2
Typical Form: Capsules, powder, tablets
Type: Organic

Magnesium taurate is an organic compound formed by combining magnesium salts with the amino acid taurine.

Unfortunately, little research is available on the relative bioavailability of magnesium taurate.

Which Is the Best Magnesium Supplement?

Infographic Showing Some of the Health Benefits of Magnesium.

Overall, there is no clear winner of the ‘best magnesium supplement’ title.

However, based on the research, magnesium chloride, citrate, gluconate, and lactate are all proven supplements for increasing blood magnesium levels.

The only direct comparison of these particular supplements was in a rat study, and this trial found that magnesium gluconate had the greatest bioavailability (15).

As with all supplements, side effects may be an issue with certain magnesium supplements.

For this reason, it is also worth noting that the best type of magnesium may depend on the individual and how they tolerate the supplement.

Key Point: Magnesium chloride, citrate, gluconate, and lactate appear to be effective and reliable according to the research.

But… Don’t Ignore Magnesium Rich Foods

Although supplements can be beneficial, the best (and safest) way to get essential nutrients is from our diet.

Foods such as cocoa, nuts, and seeds are some excellent sources of magnesium.

For more details, see this full guide to the top food sources of magnesium.

Side Effects

As with all supplements, it is essential to be aware of potential side effects.

For magnesium supplements, the common side effects are mostly gastrointestinal distress and issues such as diarrhea, but the occurrence of these vary depending on the specific compound.

It is also possible to overdose on magnesium supplements, and this can cause serious health issues (31).

As with all supplements, anyone using magnesium should stick to the dosage instructions (or their doctor’s instructions).

Final Thoughts

Magnesium is a crucial mineral for our health, and it is ideal to get the mineral from the food we eat.

However, supplements can be a useful option to boost our intake.

There are many different types of magnesium supplements, but some of the most research-proven options include magnesium chloride, citrate, gluconate, and lactate.

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Michael Joseph, MSc

Michael works as a nutrition educator in a community setting and holds a Master's Degree in Clinical Nutrition. He believes in providing reliable and objective nutritional information to allow informed decisions.

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