This article is for general information only and is not medical advice. If you have a health condition, take prescribed medication or are pregnant, speak to your doctor or pharmacist before taking magnesium.
The short answer
Magnesium glycinate and magnesium bisglycinate are usually the same thing. “Bisglycinate” is the more precise chemical name: one magnesium atom bound to two glycine molecules. “Glycinate” is the everyday shorthand. Most brands use the two names interchangeably.
The difference that actually matters isn’t the name on the front of the bottle. It’s whether the product is buffered, meaning mixed with a cheaper form such as magnesium oxide, which the label on the back will tell you.
What “bisglycinate” actually means
Glycine is the smallest amino acid. In this supplement, magnesium is held between two glycine molecules in a ring-like structure called a chelate. “Bis” simply means two, so bisglycinate describes that structure exactly.
You’ll see the same compound sold under several names:
- magnesium glycinate
- magnesium bisglycinate
- magnesium bisglycinate chelate
- magnesium diglycinate
- magnesium glycinate chelate
In practice these all refer to the same form. Because glycine makes up most of the weight, only about 10–14% of magnesium bisglycinate is actual magnesium. That’s why capsules tend to be large, and why labels list the elemental magnesium (the magnesium itself) separately from the weight of the whole compound.
Some products combine glycinate with another amino acid, such as “magnesium glycinate lysinate”. These are close relatives rather than a different category.
The difference that matters: buffered or not
Because pure glycinate contains so little magnesium by weight, some manufacturers add magnesium oxide to raise the dose per capsule. These are called buffered products. Products without added oxide are often described as non-buffered or fully reacted.
Buffering isn’t dangerous, but it changes what you’re getting. Magnesium oxide is less well absorbed and more likely to loosen stools, which is often exactly what people choosing glycinate are trying to avoid.
| On the label | What it usually means |
|---|---|
| “Magnesium (as magnesium bisglycinate)” only | Glycinate only |
| “Magnesium (as magnesium bisglycinate, magnesium oxide)” | Buffered: part of the magnesium comes from oxide |
| “Buffered” anywhere on the pack | Contains another form, usually oxide |
| “Fully reacted” or “non-buffered” | Marketed as glycinate only; check the ingredients list to confirm |
| A very high dose in one small capsule | A sign it may be buffered, given how bulky pure glycinate is |
If a label doesn’t say which forms are included, contact the brand and ask.
Why people choose glycinate, and who it doesn’t suit
Glycinate is one of the most popular forms for two reasons:
- It’s gentle on the stomach. It’s much less likely to cause loose stools than citrate or oxide.
- It’s often taken for calm and sleep. Glycine has a calming effect of its own and has been studied as a sleep aid.
That calming effect is also why glycinate doesn’t suit everyone. Some people find it too sedating, feel groggy the next morning, or feel flat during the day. If that’s you, try taking it earlier in the evening, lowering the dose, or switching to another form such as citrate or malate. Our magnesium side effects guide explains the options.
Glycinate also costs more per milligram of magnesium than most other forms, because so much of each capsule is glycine.
How much to take, and when
The NHS says adults need about 270 mg (women) to 300 mg (men) of magnesium a day, much of which comes from food such as nuts, seeds, leafy greens and whole grains. It also says taking more than 400 mg a day can cause diarrhoea.
- Read the elemental amount. “Magnesium 200 mg (as magnesium bisglycinate)” means 200 mg of actual magnesium. “Magnesium bisglycinate 1,000 mg” usually means only about 100–140 mg of magnesium.
- Start low. Many people do well on 100–200 mg of magnesium from a supplement, alongside a good diet.
- Evening suits most people, because of the calming effect. If it leaves you groggy, move it earlier.
- Check medicines. Take magnesium at a different time from some antibiotics, osteoporosis medicines and thyroid tablets. Ask your pharmacist.
Speak to your doctor before taking magnesium if you have kidney disease, a heart condition or take regular prescribed medicine.
Questions we often get asked
Is magnesium bisglycinate better than magnesium glycinate?
No. They’re the same compound under different names. Compare products on whether they’re buffered and how much elemental magnesium they contain, not on which name they use.
Is bisglycinate better absorbed than other forms?
Glycinate is generally considered well absorbed and well tolerated. Forms that dissolve well, such as citrate and chloride, are also well absorbed. Magnesium oxide is absorbed less well.
Why does my glycinate make me tired or groggy?
The glycine itself has a calming effect, and some people are sensitive to it. Try a smaller dose, an earlier time or a different form.
Can I take glycinate during the day?
Yes. Some people take it in the morning or split it between morning and evening. If it makes you drowsy, keep it to the evening.
What does “chelate” mean?
It means the magnesium is bound to another molecule, here glycine. All true glycinate products are chelates.
Comparing products? See our best magnesium glycinate supplements, and our vitamins and minerals interactions chart and our free Mineral Interaction Wheel for how magnesium works with other minerals.
Sources
- NHS. Vitamins and minerals: Others (magnesium).
- NIH Office of Dietary Supplements. Magnesium: Fact Sheet for Health Professionals.
- Yamadera W, et al. Glycine ingestion improves subjective sleep quality in human volunteers. Sleep and Biological Rhythms, 2007.
The 10–14% range reflects commercial labels (for example, 2,000 mg of bisglycinate giving 200 mg of magnesium) and the theoretical maximum from the compound’s molecular weight.