Many different forms of magnesium can be found on the supplement market, which differ primarily in their absorption capacity, but also in their additional effects. First of all, we can distinguish between organic and inorganic forms of magnesium. The differences in assimilability between organic and inorganic forms are widely reported in a plethora of studies. Magnesium from inorganic compounds is said to be absorbed in the average range of 10-16% and as low as 4% in the case of the popular magnesium oxide. This makes an incomparable difference to the absorption of magnesium from organic compounds, which is around 90%. 

References:

Maria Iskra , Beata Krasińska , Andrzej Tykarski, Magnez — rola fizjologiczna, znaczenie kliniczne niedoboru w nadciśnieniu tętniczym i jego powikłaniach oraz możliwości uzupełniania w organizmie człowieka, ViaMedica Nadciśnienie Tętnicze w Praktyce, 2013, volume 17, no. 6, p. 447-459.

In addition to good magnesium absorption, magnesium citrate supports the human digestive system. By osmosis, magnesium citrate can retain water in the intestines, which, in turn, promotes bowel movement within half an hour to six hours. Magnesium citrate will support intestinal disorders, especially constipation. In larger quantities, it is also used to empty the bowel in preparation for colonoscopy.  

References:

Eidensohn Y, Mond Y, Labowitz I, Greenberg P, Formanowski B, Eidensohn C, Dutta S, Dubin E. Magnesium Citrate Capsules in Colonoscopy Preparation: A Randomized Controlled Trial. Cureus. 2021 Dec 18;13(12):e20506. doi: 10.7759/cureus.20506. PMID: 35070543; PMCID: PMC8765591.

Magnesium salts have a very high volume. In the case of tablets or capsules, the daily serving is generally provided in 3-4 pieces in the largest size. Magnesium powder added to water is a better alternative for many people, especially if they have problems or are reluctant to swallow several large tablets throughout the day.

Magnesium is found in combination with organic or inorganic salts. To be absorbed effectively, the magnesium salt must first dissolve and release Mg2+ ions (the so-called free form). The human requirement refers to magnesium cations (Mg2+) and not to the entire compound found in the product. The mineral salt content specified on some labels is not the same as the ion content. Magnesium compounds differ in their molar mass and percentage magnesium content (as Mg2 ions). To illustrate:

• Magnesium citrate contains 15.4% magnesium ions, which means that in 1 gram of magnesium citrate there are 154 mg Mg2+.
• Magnesium taurate contains 11% magnesium ions, which means that in 1 gram of magnesium taurate there are 110 mg Mg2+.

The percentage values are always specified in the raw material certificates and may vary. Above are examples of the most common molar masses.

The best time to take magnesium is rather an ambiguous issue as there are two schools. Magnesium can have a stimulating or calming effect, depending on its form, but also the demand or deficiencies in the body. We recommend that you find your own optimal intake time, whether in the morning, during the day or in the evening.

Magnesium, together with vitamin C and carnitine, can be added to a bidon or a bottle of water and sipped throughout the day