April 16, 2026, 8:30 am | Read time: 4 minutes
Magnesium isn’t just magnesium: Depending on the compound, the mineral’s absorption by the body varies, as does its suitability for specific uses. FITBOOK nutrition expert Sophie Brünke explains the different forms of magnesium, their distinctions, and which form might be beneficial.
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Who Benefits from Extra Magnesium
Magnesium is involved in numerous biochemical reactions and cellular functions, serving as a cofactor for more than 600 enzymes.1 The mineral is crucial for muscles, the nervous system, energy metabolism, and maintaining strong bones and teeth. Typically, daily magnesium needs can be met through diet. Men require 350 milligrams of magnesium per day, while women need 300 milligrams. However, a one-sided diet, physical exertion, or stress can interfere with meeting these needs. Additionally, magnesium absorption can be reduced by high amounts of other minerals, such as calcium, iron, or zinc. A deficiency often manifests as poor sleep or muscle weakness and cramps.
Magnesium should also be monitored in cases of illness. Gastrointestinal issues, for example, can reduce the mineral’s absorption in the intestines. Particularly with chronic diarrhea, such as from Crohn’s disease or celiac disease, a magnesium deficiency can occur. The National Institutes of Health also lists type 2 diabetics, people with alcohol dependency, and older adults as risk groups.2
When Magnesium Supplements Are Useful and Which Products Are Recommended
Should You Take Magnesium Before or After Exercise?
Overview of the Most Important Magnesium Forms
Citrate, glycinate, oxide, or chloride–magnesium supplements come in various forms that differ significantly and can cause confusion in drugstores or pharmacies.
Magnesium Citrate–Perfect for Athletes
Strength, endurance, recovery–all require sufficient magnesium. Sweat loss increases the need. Athletes often complain about cramps. This is where magnesium citrate comes in: In the slightly acidic environment of the small intestine, this organic magnesium compound dissolves well and is efficiently absorbed.3
According to FH Münster, magnesium citrate is one of the most studied and efficiently absorbed magnesium compounds. It has been shown that intake leads to above-average high magnesium concentrations in the blood.4
A downside of organic magnesium compounds is the low magnesium content itself–only five to 17 percent. This means a large amount of magnesium citrate must be taken to provide sufficient magnesium.
Magnesium Glycinate–For Good Sleep
Magnesium glycinate is also an organic compound. In this case, magnesium binds to the amino acid glycine. The special feature: In this form, magnesium is stomach-friendly and has high bioavailability. Additionally, glycine has a calming effect on the nervous system. Therefore, it’s the perfect match for sleep problems, stress, or inner unrest.
Magnesium Chloride–The All-Rounder
Magnesium chloride is particularly common in inexpensive supplements. As an inorganic form, it requires more acid to dissolve. Therefore, it is absorbed more slowly and to a lesser extent by the body. Overall, its bioavailability is rated as medium to high. It is considered well-tolerated and can be used for basic supply.
The unique aspect of this form: It can also be applied externally in baths. This bypasses poor absorption through a compromised intestine. However, its effectiveness is less well-documented compared to oral intake.
Magnesium Oxide–The Right Choice for Constipation
Magnesium oxide can help with constipation. So, those who suffer from it and want to supplement magnesium can skip other laxatives–at least for mild constipation. Magnesium oxide is also inorganic. While the magnesium content per milligram is high, its bioavailability is very low. Therefore, it must be dosed accordingly high.
Proper Magnesium Dosage
According to the DGE, adult men need about 350 milligrams of magnesium daily, while women need 300 milligrams. If magnesium is supplemented, no more than 250 milligrams per day should be taken from supplements.
The key to dosage is not only the form of magnesium but especially how much elemental magnesium a product actually provides–many manufacturers list this value on the packaging. Organic compounds like magnesium citrate or glycinate are more bioavailable but contain less elemental magnesium per unit weight than magnesium oxide. Therefore, the capsule or powder amount for citrate is often larger, even though absorption in the body is more favorable. Conversely, less bioavailable forms like chloride and oxide are sometimes dosed higher to achieve comparable magnesium intake.
Be cautious with intake: The DGE points out that single doses of 300 milligrams of magnesium can cause diarrhea in adults, as magnesium binds water in the intestines. Therefore, it’s advisable to split the amount and take a small amount of magnesium in the morning and evening. Those who want to be extra cautious should opt for the stomach-friendly glycinate compound.