The very brief comparative absorption rates below are examples before the full section of “Forms of Magnesium” are introduced.
The variable availability for absorption arises from the differing forms of presentation of Magnesium:
“Food State” magnesium has availability for absorption of approximately 70% compared to Magnesium Tri-Phosphate.
Magnesium citrate has availability for absorption of approx. 8% compared to Magnesium Orotate which has an availability for absorption of approx. 30% compared to Magnesium Carbonate has an availability for absorption of approx. 5%.
This is not the end of the story. Having been absorbed, the Magnesium still needs to be in the best bioavailable state for use. In general, “FOOD STATE” form is far more bioavailable for use than any other form. It is difficult to quantify this as there are so many variable influences, but at least a factor of 2 and a half times can be accepted as usual.
The variable availability for absorption arises from the differing forms of presentation of Magnesium. It is to be remembered that of the many chemical salt forms of magnesium the actual magnesium content varies tremendously. You may find the actual amount of magnesium in the many salt forms much lower than expected.
All the magnesium forms below are as chemical salts and do not have any association with carrier proteins that are essential for the minerals delivery and use within the body.
Forms of Magnesium
This section lists the various forms of supplemental (and non-supplemental) Magnesium.
Forms of Magnesium
Extracellular Magnesium is magnesium present outside of cells. Approximately 1% of the body’s magnesium is extracellular.
Intracellular Magnesium is magnesium present within cells. Approximately 99% of magnesium is intracellular. Approximately 10% to 15% of intracellular magnesium is in an active form.
Magnesium Acetate is comprised of 11.2% magnesium bound to acetic acid (acetate). It is used as a food additive in non-alcoholic beverages.
Magnesium Arginate is comprised of magnesium bound to arginine.
Magnesium Aspartate is comprised of 7.5% – 20% magnesium bound to aspartic acid (aspartate). It is used as a nutritional supplement because its absorption is good.
Magnesium Bicarbonate (magnesium hydrogen carbonate; mg(hco3)2). This form of magnesium produces “hardness” in water.
Magnesium Carbonate (MgCO3) is comprised of 40% – 42% magnesium bound to carbon. This form of magnesium is present in dolomite, however its absorption rate is poor (23% of magnesium and carbonate is absorbed).
Magnesium Chelate is a general term for all forms of magnesium where magnesium is bound to (usually) an amino acid. The absorption of chelated forms of magnesium is good. The preferred amino acids for chelation with magnesium are aspartic acid or glycine. Most chelated forms of magnesium comprise 10 – 20% magnesium bound to 80 – 90% of an amino acid.
This form of magnesium is produced from a fermentation process. The fermentation of yeast does produce undesirable by-products such as urethane/ethyll carbamate that is damaging (a carcinogen) to the immune system and associated with serious disease processes.
Magnesium Chloride (MgCl2) consists of 11.8% magnesium bound to 88.2% chloride. It is used as a food additive in non-alcoholic beverages and as a liquid form of magnesium supplementation.
Magnesium Citrate (mg3(c6h5o7)2) consists of 10.0% – 16.4% magnesium bound to 83.8 – 90.0% citric acid. Its molecular weight is 451.13. Its oral absorption is good as it is less dependent upon hydrochloric acid for absorption compared with magnesium oxide.
Magnesium Diglycinate is a form of chelated magnesium that consists of magnesium bound to glycine. An average of 23.5% of magnesium from magnesium diglycinate is absorbed.
Magnesium Fumarate consists of magnesium bound to fumaric acid. Its oral absorption is good.
Magnesium Gluconate (c12h22o14) consists of 5.3% magnesium bound to 94.7% gluconic acid. This form does not cause diarrhoea and is used as a buffering agent in soda water. Its oral absorption is good. Its molecular weight is 450.64.
Magnesium Glycinate is a form of chelated magnesium. It consists of 10% – 18% magnesium bound to 82% – 90% glycine. The oral absorption of magnesium glycinate is regarded as good.
Magnesium Hydroxide (Mg(OH)2) is a common, inexpensive form of supplemental Magnesium. It is also used pharmaceutically as an antacid and as a laxative:
Milk of Magnesia is a suspension of 8% magnesium hydroxide in water.
Magnesium Lactate (c6h10mgo6) consists of 10.0% to 12.2% magnesium bound to lactic acid. The oral absorption of magnesium lactate is regarded as good. Its molecular weight is 238.47.
Magnesium Malate (mgc4h4o5) consists of 12% to 15% magnesium bound to 85% to 87% malic acid. The oral absorption of magnesium malate is regarded as good. Its molecular weight is 210.4.
Magnesium Orotate consists of 6.9% – 7.5% magnesium bound to Orotic acid. The oral absorption of magnesium orotate is regarded as good.
Magnesium Oxide (calcined Magnesia; magnesia; MgO) consists of 57% – 60.6% magnesium bound to oxide. It is not readily absorbed but is absorbed better than magnesium carbonate. Magnesium oxide is sometimes used pharmaceutically as an antacid and a laxative. It causes diarrhoea in some people.
Its molecular weight is 40.3. Magnesium oxide is dependent upon hydrochloric acid for absorption. Without hydrochloric acid, virtually none is absorbed (4% in one clinical study). With optimal hydrochloric acid in the stomach, approximately 43% is absorbed.
Magnesium Phosphate is an inorganic form of magnesium that consists of magnesium bound to phosphorus the oral absorption of magnesium phosphate is regarded as good.
Magnesium Picolinate consists of magnesium bound to picolinic acid. The oral absorption of magnesium picolinate is regarded as good. Picolinic acid is believed to significantly enhance the oral absorption of magnesium however there are concerns regarding this substance as it may generate hydroxyl free radicals.
Magnesium Pidolate (also known as magnesium pyrrolidone-carboxylate) contains 8% elemental magnesium.
Magnesium Silicate is an inorganic form of magnesium that consists of magnesium bound to silica. It is used as a food additive in table salt as an anti-caking agent.
Magnesium Stearate consists of 4.5% magnesium bound to stearic acid. This is not a supplemental form of magnesium but is used as an anti-caking agent food additive.
Magnesium Succinate consists of 14.5% – 16.84% magnesium bound to succinic acid. It is regarded as a good supplemental form of magnesium.
Magnesium Sulphate (magnesium sulphate; mgso4) consists of 9.7% magnesium bound to sulphur. Magnesium sulphate is not very well absorbed into the body but attracts water in the colon and acts as a laxative. People with impaired kidney function should not consume this form of magnesium:
Epsom Salts (MgSO4 7H2O) are a form of hydrated magnesium sulphate produced commercially by reacting magnesium carbonate with sulphuric acid.
Magnesium Taurate (also known as magnesium taurinate) consists of 25% magnesium bound to 75% taurine.