On the market there exist dozens of dietary supplements with magnesium. Citrate, bisglycinate, malate, taurate, oxide or L-threonate — what is the difference between them and which form to choose? In this article we will explain how the individual forms of magnesium differ, what is their absorbability, for whom they are most suitable, and which ones to rather avoid.
What will you learn from this article:
- Why the form of magnesium matters
- Organic vs. inorganic forms
- The most suitable forms — bisglycinate, L-threonate, malate or taurate
- Which magnesium to choose according to your needs
- Why oxide, carbonate, hydroxide or citrate are used less
- Key Takeaways
Why the form of magnesium matters
Magnesium is the fourth most abundant mineral in the human organism, where it participates in more than 300 enzymatic processes. It is key for energy production, correct function of muscles and the nervous system, and also for bone health. Although its importance is well known, among individual dietary supplements there exist significant differences. [1] And that not only in the contained form, but also in quality. About this topic we already wrote in the article Magnesium and the content of dangerous contaminants.
The deciding factor is not only the amount of elemental magnesium stated on the label, but above all the chemical form in which the mineral is bound. This affects its solubility, absorption in the intestine, bioavailability, and gastrointestinal tolerance. A systematic review published in the journal Nutrition shows that organic salts of magnesium generally show higher bioavailability than inorganic salts. The rate of absorption, however, also depends on the dose and the health state of the organism. [2]
Often orientational values of bioavailability of individual forms of magnesium are given. The highest absorbability is attributed to bisglycinate (80–90%) and L-threonate (70–80%), followed by malate (50–70%) and citrate (25–35%). Conversely magnesium oxide is usually stated with bioavailability of approximately 4–10%, hydroxide 5–10% and carbonate 10–20%. It is however important to emphasize that these percentages come predominantly from orientational estimates. The actual rate of absorption depends on a number of factors, such as dose and health state. Expert studies, such as for example the one titled Bioavailability of US Commercial Magnesium Preparations. Magnesium Research, agree above all that organic forms of magnesium are generally biologically more available than inorganic forms.
Organic vs. inorganic forms
Chemical forms of magnesium can be simplified and divided into two groups:
Organic forms are bound to organic molecules, most often amino acids (glycine) or "fruit" acids (malic acid or citric acid). Thanks to higher solubility they tend to be better absorbable and at the same time gentler on the digestive tract. [2][3]
Inorganic forms (oxide, hydroxide or carbonate) contain a high percentage of elemental magnesium, however its utilizability is many times lower. [4] Therefore they are more often used as antacids (substances for reducing stomach acidity) or laxatives, rather than for long-term magnesium supplementation. Systematic reviews confirm that organic salts show in the majority of studies higher bioavailability than inorganic salts. [2][4]
The most suitable forms — bisglycinate, L-threonate, malate or taurate
Magnesium bisglycinate
Bisglycinate belongs among the best biologically available forms of magnesium. It is a chelate, in which the magnesium atom is bound to two molecules of the amino acid glycine.
This bond protects the magnesium from interactions in the digestive tract and enables its effective absorption. [3] At the same time bisglycinate is known for very good gastrointestinal tolerability and only minimal laxative effect, which makes it a suitable form for long-term supplementation. [5]
Another advantage is glycine itself, which acts as an inhibitory neurotransmitter in the central nervous system and participates in the regulation of sleep and relaxation. [6] It is therefore not surprising that it is precisely bisglycinate that tends to be the most often recommended form during increased psychological strain or sleep disorders. A randomized double-blind study published in the journal Nutrients in 2025 showed that supplementation of 250 mg of elemental magnesium in the form of bisglycinate led, in persons with worse sleep quality, to a mild but statistically significant improvement of insomnia.
Magnesium L-threonate
L-threonate is a relatively new and patented form of magnesium Magtein® developed with the goal of increasing the concentration of magnesium in the central nervous system. About this form of magnesium we also wrote in more detail in the article Discover ThreoMag: an innovative form of magnesium for better memory, concentration and brain health.
Unlike other forms it was designed so as to effectively overcome the blood-brain barrier, which separates brain tissue from the blood circulation. Experimental studies on animals indicate an increase of magnesium concentration in brain tissue and support of the formation and function of nerve connections. [9] Precisely for this reason L-threonate is intensively researched in connection with memory, learning and healthy brain aging. Clinical studies conducted on humans are however for now significantly fewer than for the other forms. [10]
Magnesium malate
Magnesium malate represents a compound of magnesium with malic acid (malate), which is a natural intermediate product of the citric acid (Krebs) cycle — the main metabolic pathway ensuring the production of cellular energy in the form of ATP. [7]
Thanks to good solubility it belongs among the well-absorbable organic forms of magnesium. In practice it tends to be often recommended especially to physically active persons or people suffering from fatigue, although direct clinical evidence confirming its "superiority" compared to other organic forms is for now limited. [9] Current review works place it among the well biologically available forms suitable for common supplementation, especially if your goal is increasing energy. [2]
Magnesium taurate
Magnesium taurate is an organic form of magnesium, in which the mineral is bound to the amino acid taurine. Thanks to good solubility it is characterized by good bioavailability and tends to be well tolerated even with long-term use. Its exact bioavailability has however not been established. Taurine occurs naturally especially in the heart, brain and muscle tissue and participates in the regulation of nerve signaling and normal function of the heart muscle. Therefore magnesium taurate is often recommended especially for support of the cardiovascular system and the nervous system. Direct clinical studies evaluating its effectiveness are however for now fewer than for bisglycinate or citrate, and the majority of the presumed benefits come from the properties of taurine and magnesium themselves. [2][12]
Which magnesium to choose according to your needs
The choice of a specific form of magnesium should not be random and should primarily reflect your individual goals, lifestyle and possible health difficulties. Read also the article How do I know that I need to supplement magnesium and zinc? Based on clinical data and bioavailability, recommendations can be divided into the following categories.
Stress, anxiety, cramps and sleep problems:
If you are looking for magnesium for calming the organism, supporting the nervous system and relaxing muscles, the ideal choice is magnesium in the form of bisglycinate. The amino acid glycine in this bond synergistically supports relaxation, dampens excess brain activity and contributes to better sleep quality, without irritating the stomach. [5][6]
Fatigue, exhaustion and during sports strain:
If you need to support energy metabolism and muscle functions during the day, choose magnesium malate. Malic acid directly participates in the cellular cycle of energy production (ATP), which makes this form a suitable morning or forenoon dietary supplement for active individuals. [7][8] Do you want to know what other dietary supplements you can take to support recovery during sports strain? Take a look at the article Supplementation in sport for support of performance and recovery.
Support of memory, concentration and cognitive functions:
If your goal is support of mental performance or healthy brain aging, consider magnesium L-threonate. As one of the few forms it is able to effectively increase the level of magnesium directly in the cerebrospinal fluid and thus support the synaptic plasticity of neurons, which relate for example to memory and learning. [9][10]
Support of the heart and nervous system:
If you want to support the normal function of the heart and the nervous system, you can choose magnesium taurate. This organic form is generally well absorbed, its effects however are not yet researched as extensively as those of bisglycinate or citrate. [2][12]
During acute constipation or heartburn:
In cases where you do not need to supplement the amount of magnesium in the body, but you are dealing with local digestive difficulties, inorganic forms such as magnesium oxide or hydroxide find application, but also citrate (an organic form). Due to low absorbability they remain in the intestine, where they act osmotically (attract water) and function as an effective laxative or antacid. [4][11]
Why oxide, carbonate, hydroxide or citrate are used less
Inorganic salts, such as magnesium oxide, hydroxide or carbonate, do contain a high proportion of elemental magnesium, their bioavailability however is generally lower than that of organic forms. [4] For this reason they are usually not the first choice for long-term magnesium supplementation.
Oxide or hydroxide are therefore more often used in medicinal preparations intended for the relief of heartburn or the treatment of constipation. [11]
Magnesium citrate (this is a compound of magnesium with citric acid) represents a transition between the most often recommended organic forms and the less suitable inorganic salts. Thanks to good solubility it is generally characterized by higher bioavailability than magnesium oxide or hydroxide and in specific cases can be suitable for common supplementation. Compared to bisglycinate, however, it more often acts osmotically in the intestine, and especially at higher doses can cause looser stool or diarrhea. Precisely for this reason, with long-term magnesium supplementation or in persons with sensitive digestion, bisglycinate tends to be often preferred, while citrate can be a suitable choice for persons with a tendency to constipation. [2][4]
Key Takeaways
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The most important thing is not the amount of magnesium, but its form: This decides how well the magnesium is absorbed, utilized in the organism and how it will be tolerated by the digestive tract.
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Organic forms of magnesium generally belong among the better absorbable ones than inorganic forms: For long-term supplementation, therefore, bisglycinate, malate or L-threonate are most often recommended.
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Each form of magnesium has its specific use: Bisglycinate is suitable for stress and sleep problems, malate for fatigue and physical strain, L-threonate is a promising choice for support of cognitive functions, and magnesium taurate has its justification for support of the cardiovascular system.
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Inorganic forms, such as magnesium oxide or hydroxide, are not ideal for magnesium supplementation: Due to lower absorbability they are more often used as means against heartburn or for constipation.
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The best form of magnesium does not exist universally for everyone: When choosing a dietary supplement you should take into account your health needs, lifestyle and supplementation goal. A well-chosen form will allow you to make use of the potential of magnesium as effectively as possible.
Sources:
[1] de Baaij, J. H., Hoenderop, J. G., & Bindels, R. J. (2015). Magnesium in man: implications for health and disease. Physiological Reviews. https://journals.physiology.org/doi/full/10.1152/physrev.00012.2014?rfr_dat=cr_pub++0pubmed&url_ver=Z39.88-2003&rfr_id=ori%3Arid%3Acrossref.org
[2] Schuchardt, J. P., & Hahn, A. (2017). Intestinal Absorption and Factors Influencing Bioavailability of Magnesium-An Update. Current Nutrition & Food Science / Nutrition. https://www.eurekaselect.com/article/83107
[3] Siebrecht, S. (2013). Magnesium Bisglycinate as safe form for Magnesium Supplementation in Human Nutrition. OM & Ernährrung. https://www.researchgate.net/publication/286153648_Magnesium_bisglycinate_as_safe_form_for_magnesium_supplementation_in_human_nutrition
[4] Firoz, M., & Graber, M. (2001). Bioavailability of US commercial magnesium preparations. Magnesium Research. https://pubmed.ncbi.nlm.nih.gov/11794633/
[5] Schuette, S. A., Lashner, B. A., & Janghorbani, M. (1994). Bioavailability of magnesium diglycinate vs magnesium oxide in patients with ileal resection. Journal of Parenteral and Enteral Nutrition. https://aspenjournals.onlinelibrary.wiley.com/doi/10.1177/0148607194018005430
[6] Kawai, N., et al. (2015). The Sleep-Promoting and Hypothermic Effects of Glycine are Mediated by NMDA Receptors in the Suprachiasmatic Nucleus. Neuropsychopharmacology. https://pubmed.ncbi.nlm.nih.gov/25533370/
[7] Chronic Organic Magnesium Supplementation Enhances Tissue-Specific Bioavailability and Functional Capacity in Rats: A Focus on Brain, Muscle, and Vascular Health (2025). Biological Trace Element Research. https://doi.org/10.1007/s12011-025-04678-y
[8] Uysal, N., et al. (2019). Timeline (Bioavailability) of Magnesium Compounds in Hours: Which Magnesium Compound Works Best? Biological Trace Element Research. https://link.springer.com/article/10.1007/s12011-018-1351-9
[9] Slutsky, I., et al. (2010). Enhancement of learning and memory by elevating brain magnesium. Neuron. https://www.sciencedirect.com/science/article/abs/pii/S0140197110000151?via%3Dihub
[10] Liu, G., et al. (2016). Efficacy and Safety of MMFS-01, a Synapse Density Enhancer, for Treating Cognitive Impairment in Older Adults: A Randomized, Double-Blind, Placebo-Controlled Trial. Journal of Alzheimer's Disease. https://journals.sagepub.com/doi/10.3233/JAD-150538?url_ver=Z39.88-2003&rfr_id=ori:rid:crossref.org&rfr_dat=cr_pub%20%200pubmed
[11] Mori, S., Tomita, T., Fujimura, K., et al. (2019). A Randomized Double-blind Placebo-controlled Trial on the Effect of Magnesium Oxide in Patients With Chronic Constipation. Journal of Neurogastroenterology and Motility, 25(4), 563–575. https://www.jnmjournal.org/journal/view.html?doi=10.5056/jnm18194
[12] Shao, A., & Hathcock, J. N. (2008). Risk assessment for the amino acids taurine, L-glutamine and L-arginine. Regulatory Toxicology and Pharmacology, 50(3), 376–399. https://www.sciencedirect.com/science/article/abs/pii/S027323000800010X?via%3Dihub
