Bisglycinate, citrate, marine, malate: faced with a magnesium shelf, the labels look alike and the price differences raise questions. Yet, the forms are not equal, and the difference comes down to three measurable criteria: the elemental magnesium content, theabsorption and digestive tolerance. This comparative breaks them down, explains the common label-reading pitfall (milligrams of salt are not milligrams of magnesium), and gives you the selection criteria based on your profile. Once you've chosen your form, the complete instructions are in our guide magnesium: morning or evening.
The comparative verdict: the bisglycinate offers the best absorption-tolerance balance: chelated form with glycine, comfortable even for sensitive intestines, with no laxative effect at usual doses. The citrate is the correct and economical alternative, well absorbed but with a slight osmotic effect that can accelerate transit at high doses. The marine magnesium, often dominated byoxide, displays record elemental content on the label but among the lowest absorption rates and lesser tolerance. The reading pitfall: comparing products based on elemental magnesium (bisglycinate approximately 10 to 14%, citrate approximately 16%, oxide approximately 60% of salt weight), never on total salt weight.
The 3 criteria that really set the forms apart
In a supplement, magnesium is never alone: it is bound to a carrier (glycine, citric acid, oxygen for oxide, malic acid...) that forms a magnesium salt. Three criteria make it possible to compare these salts:
- Elemental magnesium content : the amount of actual magnesium in the salt's weight. This is the classic label trap: 300 mg of magnesium bisglycinate does not provide 300 mg of magnesium, but approximately 10 to 14% of that weight. Oxide contains approximately 60%, citrate approximately 16%. The only honest comparison between two products is based on the elemental magnesium line (or the percentage of NRVs).
- Absorption : the fraction actually absorbed by the intestine. Organic and chelated forms (bisglycinate, citrate, malate) are generally better absorbed than inorganic forms like oxide, whose solubility is low.
- Digestive tolerance : poorly absorbed magnesium remains in the intestine and attracts water, hence the laxative effect of certain forms at high doses. The better absorbed and more stable a form is, the more comfortable it is.
The comparison: bisglycinate, citrate, marine, malate
| Form | Elemental | Absorption | Digestive tolerance | Profile |
|---|---|---|---|---|
| Bisglycinate (glycine chelated) | Approximately 10-14% | Good | Excellent, no laxative effect at usual doses | Daily use, sensitive intestines, long-term treatments |
| Citrate | Approximately 16% | Good | Adequate, osmotic effect possible at high doses | Budget-friendly alternative, sluggish transit |
| Marine (predominantly oxide) | High, approximately 50-60% | Low | Lower at high doses | Natural image, supplementary support, flattering labels |
| Malate | Approximately 15% | Good | Good | Often paired with bisglycinate in comprehensive formulas |
Two readings of this table deserve clarification. First, the paradox ofoxide (and therefore most marine magnesiums): its record elemental content allows large numbers to be displayed on the label for low cost, but its poor absorption and lower tolerance make it a poor compromise when the goal is to genuinely nourish your status with comfort. Then the case of malate : a well-balanced organic form, often found in combination with bisglycinate in well-designed formulas, the two complementing each other without competing.
Why bisglycinate stands out
<<<21>>> Bisglycinate bisglycinate binds each magnesium atom to two molecules of glycine, an amino acid. This chelation concretely changes three things:
- Digestive stability : the complex passes through the stomach and intestines without suddenly breaking apart, which limits the osmotic effect responsible for accelerating transit
- Tolerance : it is the reference form for sensitive stomachs and extended supplementation, where other forms require dose reduction or discontinuation
- Sustainable regularity : a comfortable supplement is one you take every day, and it's consistency that builds your status, as detailed in our guide on morning or evening
To be honest: citrate remains a proper and well-absorbed form, and someone who tolerates it perfectly has no compelling reason to switch. Bisglycinate distinguishes itself when digestive comfort, daily dosage, or supplementation duration come into play—that is, in most real-world uses. This is the choice we made for our Magnesium+.
Which form according to your profile
- Sensitive digestion, or past negative experience with magnesium : bisglycinate, without hesitation
- Extended supplementation (2-3 months) or high daily dose taken in divided doses : bisglycinate, for lasting tolerance
- Tight budget and robust digestion : citrate, monitoring comfort if the dose increases
- Sluggish transit : citrate can be an ally, its osmotic effect becoming an advantage
- Attracted to marine magnesium : verify the actual composition (often dominated by oxide) and the elemental magnesium line before comparing prices; at equal absorption, it is rarely the good deal it appears to be
In all cases, the intake rules remain the same regardless of the form: with meals, splitting of high doses, 2-hour spacing with relevant medications (tetracyclines, quinolones, levothyroxine, bisphosphonates), and ANSES references first (380 mg/day men, 300 mg/day women, including dietary intake). For the duo with vitamin D, see our guide magnesium and vitamin D.
Compare products based on elemental magnesium and follow the dosage on the label. Beyond 250 mg per day of additional intake in a single dose, laxative effects may appear in some people, regardless of the form: split the dose. Kidney insufficiency, chronic treatment, pregnancy: professional advice before supplementation. A dietary supplement does not replace a varied and balanced diet or a healthy lifestyle.
Frequently asked questions
What is the best form of magnesium?
No perfect form, but the best compromise on three criteria: elemental content, absorption, tolerance. Bisglycinate offers the best overall balance (chelated, well absorbed, excellent tolerance). Citrate is the correct and economical alternative. Marine magnesium, often dominated by oxide, displays a record content but poor absorption.
What is the difference between bisglycinate and citrate?
Bisglycinate is chelated to glycine: stable, very well tolerated, including by sensitive intestines. Citrate is well absorbed and less costly, but its osmotic effect can accelerate transit at high doses. At equal elemental intake, the difference comes down to digestive comfort and regularity it provides.
Is marine magnesium a good choice?
Its natural image appeals, but it is most often dominated by oxide: very high elemental content on the label, absorption among the lowest, reduced tolerance at high doses. As a supplement, why not; to effectively nourish your status with comfort, chelated forms are better suited.
What does elemental magnesium mean?
The amount of real magnesium, excluding the carrier. Bisglycinate: approximately 10-14% of salt weight; citrate: approximately 16%; oxide: approximately 60%. It is the elemental line (or % of RV) that allows you to honestly compare two products, never the total weight of the salt.
Does bisglycinate have laxative effects?
That is its strong point: at usual doses, no laxative effect, with chelation reducing the osmotic effect. The general guideline remains valid for all forms: beyond 250 mg/day additional in a single dose, laxative effects may appear in some people. Splitting the dose is enough to stay comfortable.
Can you change forms during supplementation?
Yes, without transition: what matters is regular elemental magnesium intake. The most common reason is digestive comfort, typically a switch to bisglycinate. Maintain the same rules: with meals, splitting of high doses, 2-hour spacing with relevant medications.
Glossary
- Elemental magnesium
- The amount of real magnesium provided by a salt, excluding carrier weight. The only honest basis for comparison.
- Chelation
- Stable binding of a mineral to amino acids (here glycine), which improves digestive stability and tolerance.
- Osmotic effect
- Attraction of water into the intestine by unabsorbed magnesium, responsible for the laxative effect of certain forms at high doses.
Sources
- ANSES. Nutritional references in vitamins and minerals: magnesium, 380 mg/day (men) and 300 mg/day (women). anses.fr
- European Commission / EFSA. Register of authorized health claims for magnesium; opinion on additional magnesium intakes. efsa.europa.eu
