Magnesium forms: citrate vs glycinate vs threonate vs oxide
Why does the magnesium form matter?
Pure magnesium is unstable, so in supplements it is always bound to something else – an acid or an amino acid. That bond determines how much is absorbed (bioavailability) and how gentle it is on the stomach. That is why two bottles of "500 mg magnesium" can deliver different results.
Magnesium forms compared
| Form | Absorption | Best suited for | Gentle on the stomach |
|---|---|---|---|
| Citrate | High | All-round, sleep, constipation | Yes at moderate doses |
| Glycinate (bisglycinate) | High | Sleep, stress, sensitive stomach | Yes, very |
| Malate | High | Daytime energy, tiredness | Yes |
| Threonate | High | Discussed for brain and memory | Yes |
| Taurate | High | Heart and calm | Yes |
| Oxide | Low | Constipation, cheap basic top-up | Often loose stools |
Magnesium citrate – the all-rounder
Citrate is magnesium bound to citric acid. It is well absorbed and good value, which makes it a common first choice. At higher doses it is mildly laxative, which can be an advantage for constipation but a drawback if you are sensitive.
Magnesium glycinate – for sleep and a sensitive stomach
Glycinate is bound to the amino acid glycine, which is calming in its own right. The form is gentle on the stomach and a common choice for the evening. Many people choose glycinate specifically for sleep and winding down.
VitaNord Magnesium uses a well-absorbed citrate form – contributes to normal muscle function and a reduction of tiredness.
See current price »Threonate, malate, taurate and oxide
- Threonate: highlighted in research for reaching the brain. The evidence is still limited, but the form is popular for focus.
- Malate: bound to malic acid, which is involved in energy metabolism. Popular during the day.
- Taurate: bound to taurine, often associated with heart and calm.
- Oxide: a high proportion of magnesium per gram but low absorption. Best for constipation, worst if you want to top up your levels.
Which magnesium form should you choose?
Start from your goal:
- Sleep and stress: glycinate or citrate in the evening.
- Energy and tiredness: malate or citrate in the morning.
- Constipation: citrate or oxide.
- Sensitive stomach: glycinate.
Whatever the form, the same dosage advice applies – see how much magnesium per day. If you want to compare finished products, check the guide to the best magnesium.
What does the amount of elemental magnesium mean?
An important detail that is easy to miss: the number on the bottle can refer either to the total amount of magnesium compound or to the amount of pure, elemental magnesium. Oxide contains a high proportion of magnesium per gram but is poorly absorbed, while glycinate contains a lower proportion but is well absorbed. So look at how much elemental magnesium a dose provides, not just the total capsule content.
Combined products and buffered forms
Many supplements blend several forms, for example citrate and glycinate, to get both good absorption and gentleness. That is rarely wrong, but it makes it harder to know exactly how much of each you are getting. So-called buffered magnesium is oxide blended with a milder form to reduce the risk of loose stools. Read the ingredient list so you know what you are actually buying.
Does price matter?
Partly. Oxide is cheapest but delivers the least absorbed magnesium for your money once you count the elemental amount. Citrate tends to be the best value among the well-absorbed forms, while threonate and taurate usually cost more. For most people, citrate or glycinate offer the best balance of price, absorption and stomach comfort.
How to switch forms if something isn't working
- If oxide or citrate gives you loose stools – try glycinate.
- If malate makes you feel wired in the evening – move it to the morning.
- If you notice no effect at all – check that the dose provides enough elemental magnesium.
The right form is rarely about a single winner, but about what suits your stomach, your goal and your wallet.
Powder, capsule or tablet?
The form matters most, but the delivery format also affects how it fits your daily routine.
- Capsules: easy to dose and tasteless. The most common and most convenient for most people.
- Tablets: often cheaper per dose, but can be large to swallow.
- Powder: easy to adjust the dose and mix into water, but citrate powder can taste tart.
Absorption is determined more by the chemical form of the magnesium than by whether it is powder or capsule. Choose the format you will actually use regularly – the best form doesn't help if the bottle sits untouched.
Quick recommendation by need
| Your goal | Form to start with |
|---|---|
| Sleep and winding down | Glycinate or citrate in the evening |
| Energy and tiredness | Malate or citrate in the morning |
| Sensitive stomach | Glycinate |
| Constipation | Citrate or oxide |
| All-round at a good price | Citrate |
Frequently asked questions
Which magnesium form is best absorbed?
Organic forms such as citrate, glycinate, malate and threonate are absorbed considerably better than oxide. The difference in bioavailability means a lower dose of a well-absorbed form can deliver as much magnesium as a higher dose of oxide. For topping up your levels, citrate and glycinate are safe, good-value choices for most people.
Is magnesium citrate or glycinate best?
Both are well absorbed. Citrate is good value and versatile but mildly laxative at high doses. Glycinate is gentler on the stomach and suits anyone who gets loose stools from citrate, or who wants to take it in the evening. If you have a sensitive stomach, choose glycinate. If you want an all-round form, citrate works well.
What is magnesium threonate good for?
Threonate is highlighted in research for its ability to reach the brain, and is discussed for memory and focus. The evidence still comes mostly from animal studies and small trials, so don't draw big conclusions. If you just want to top up magnesium generally, citrate or glycinate are enough and have more research behind them.
Is magnesium oxide bad?
Not bad, but it is absorbed less well than other forms. Oxide contains a lot of magnesium per gram but only a small proportion reaches the blood, and the rest draws water into the gut. That is why it works well for constipation but less well for raising magnesium levels. If you want to top up, choose a well-absorbed form.