supplements · 2 min read
Magnesium glycinate vs bisglycinate: the same compound, two names
Magnesium glycinate and magnesium bisglycinate are the same molecule: one magnesium ion bound to two glycine molecules. The difference that matters is whether a product is buffered with magnesium oxide, which the name alone will not tell you.
Written by Lifebar Desk · Checked against the sources listed below
Published 26 Sept 2026
Key takeaways
- Magnesium is divalent, so it binds two glycine molecules. "Bisglycinate" is the precise chemical name, "glycinate" is the common one.
- Pure magnesium bisglycinate is about 14% elemental magnesium by weight.
- Some products labelled glycinate are "buffered" with magnesium oxide, which raises the magnesium per capsule but brings back the laxative effect.
- Check the supplement facts panel for the elemental magnesium figure and for magnesium oxide in the ingredient list.
If you are standing in a supplement aisle choosing between magnesium glycinate and magnesium bisglycinate, you are choosing between two labels for the same thing.
Why there are two names
Magnesium carries a 2+ charge. Glycine, the amino acid it is bound to, carries a single negative charge at the binding site. So one magnesium ion binds two glycine molecules. Chemists call that magnesium bisglycinate (or diglycinate). Marketing shortened it to magnesium glycinate. The molecule does not change.
The difference that is real: buffering
The label to watch is not "glycinate" versus "bisglycinate" but whether the product is buffered.
| Unbuffered bisglycinate | Buffered glycinate | |
|---|---|---|
| What is in it | Magnesium bound to glycine | Glycinate blended with magnesium oxide |
| Elemental magnesium | About 14% by weight | Higher, varies by blend |
| Pills per 200 mg magnesium | Often 2 to 4 | Often 1 to 2 |
| Gut tolerability | Gentle | Closer to oxide, more loose stools |
| How to spot it | Only bisglycinate or glycinate listed | "Buffered", or magnesium oxide in the ingredients |
Neither is dangerous. The trade is convenience against tolerability, and if you chose glycinate precisely to avoid the laxative effect, a buffered product undoes part of the reason.
What the absorption evidence says
The best-known human comparison studied patients with ileal resection, a group that absorbs magnesium poorly. Magnesium diglycinate was absorbed better than magnesium oxide. That supports the chelate over oxide. It does not show that one brand of glycinate beats another, and no trial compares "glycinate" with "bisglycinate", because there is nothing to compare.
Reading the label
- Find the elemental magnesium figure on the supplement facts panel, not the compound weight on the front.
- Scan the ingredient list for magnesium oxide or "buffered".
- Keep supplemental magnesium at or below 350 mg of elemental magnesium a day unless a clinician advises otherwise. Magnesium from food does not count toward that limit.
One caveat
Magnesium is cleared by the kidneys. With reduced kidney function it can build up, so check with your clinician before starting any form.
Frequently asked
Is magnesium bisglycinate better than magnesium glycinate?
No. They are the same compound. Any real difference between two products comes from buffering, dose or fillers, not from the name.
What does "buffered" magnesium glycinate mean?
The glycinate has been blended with magnesium oxide or another cheaper salt. It lets a manufacturer fit more magnesium into a capsule, but oxide is poorly absorbed and more likely to loosen stools.
What does "fully reacted" or "chelate" on the label mean?
It is a manufacturer claim that the magnesium is bound to glycine rather than simply mixed with it. It is the property you are paying for, but it is not independently verified on most labels.
How much elemental magnesium is in 500 mg of magnesium bisglycinate?
About 70 mg if unbuffered, since the compound is roughly 14% magnesium by weight. A buffered product can list more elemental magnesium per 500 mg because oxide is about 60% magnesium.
Sources
Educational content, talk to your clinician before changing treatment.
