Last updated: October 2026
Magnesium glycinate is the gentlest form and the usual choice for evenings and stress. Magnesium citrate is well absorbed and has a mild laxative effect, so it suits constipation. Magnesium L-threonate costs more and is mainly studied for the brain. Oxide is cheap but poorly absorbed. For most people, glycinate or a glycinate and citrate blend is the best start.
This guide compares every popular form side by side, including malate, bisglycinate and oxide, with how much real magnesium each contains, what the research says and who each one suits.
Comparison table: which magnesium is best?
Every magnesium supplement is magnesium bound to another substance. That partner changes how much magnesium you get per gram, how well it is absorbed and how it feels on your stomach.
| Form | Bound to | Magnesium content (approx.) | Stomach | Most often used for |
|---|---|---|---|---|
| Glycinate (bisglycinate) | Glycine, an amino acid | About 14% | Very gentle | Evenings, stress, everyday top-up |
| Citrate | Citric acid | About 16% | Can loosen stools | Constipation, well-absorbed top-up |
| L-threonate | Threonic acid | About 7 to 8% | Gentle | Brain, focus, memory |
| Malate | Malic acid | About 15% | Gentle | Daytime energy, muscles |
| Oxide | Oxygen | About 60% | Often loosens stools | Cheap tablets, constipation |
The percentage matters. A capsule with “1,000mg magnesium glycinate” holds only about 140mg of actual (elemental) magnesium, so always check the elemental figure on the label. For more forms, see our guide to types of magnesium.
Magnesium glycinate vs citrate
These are the two most popular forms in the UK, and both are well absorbed. The main difference is what they do in your gut.
| Glycinate | Citrate | |
|---|---|---|
| Absorption | Good | Good |
| Laxative effect | Low | Mild to moderate, more at higher doses |
| Best time | Evening | Any time; evening if used for constipation |
| Choose it if | You want an evening routine or have a sensitive stomach | You also want to keep things moving |
Choose glycinate if you want magnesium as part of a wind-down routine or have found other forms upset your stomach. Glycine is an amino acid in its own right, and many people find this form the easiest to take every day. Read more in our magnesium glycinate guide.
Choose citrate if you are prone to constipation. It draws water into the bowel, which is why it helps some people stay regular, and why too much can cause loose stools. See magnesium for constipation and magnesium for bloating.
Our Magnesium Glycinate Sleep Complex uses both: bisglycinate for gentleness plus citrate, giving 148mg of elemental magnesium per serving, taken as a warm evening drink.
Magnesium glycinate vs threonate
Magnesium L-threonate was developed by researchers studying how to raise magnesium levels in the brain. In animal studies it did this better than other forms, which is why it is marketed for memory and focus.
- Brain: in a 12-week trial of 44 adults aged 50 to 70 with memory complaints, a threonate supplement improved overall scores on thinking tests compared with placebo.
- Sleep: in a 2024 trial of 80 adults with poor sleep, 1g a day of threonate for 3 weeks improved sleep quality scores and mood compared with placebo. The study was funded by the company that supplies the ingredient.
| Glycinate | L-threonate | |
|---|---|---|
| Magnesium per gram | About 140mg | About 70 to 80mg |
| Research focus | General magnesium intake | Brain and sleep, small trials |
| Cost per mg of magnesium | Lower | Much higher |
| Best for | Daily top-up, evenings, stress | People specifically interested in focus and memory |
Because threonate contains so little magnesium, it won’t do much to top up low levels on its own. If your main aim is an evening routine or correcting a shortfall, glycinate is the simpler and cheaper choice. If you want to try threonate for focus, it can be taken alongside. More in magnesium L-threonate and magnesium for sleep.
Magnesium citrate vs threonate
These do quite different jobs. Citrate is an affordable, well-absorbed way to raise your magnesium intake, with a mild laxative effect. Threonate is a specialist form that gives little magnesium per dose but has been studied for the brain. Choose citrate for general intake or constipation, and threonate only if focus and memory are your main interest.
What about oxide, malate and bisglycinate?
- Magnesium bisglycinate vs glycinate: they are the same thing. Bisglycinate means each magnesium is bound to two glycine molecules, which is how magnesium glycinate is made. Brands use the names interchangeably.
- Magnesium oxide: the cheapest form and common in supermarket tablets. It contains a lot of magnesium by weight, but much less is absorbed. In a University of Reading trial, oxide performed no better than placebo for raising magnesium levels. It is more likely to cause loose stools.
- Magnesium malate: bound to malic acid, which is involved in energy production. It is gentle and often taken in the daytime, but there is little research comparing it directly with glycinate.
- Magnesium taurate, chloride and sulphate: taurate is sometimes chosen for heart health, chloride is used in sprays and flakes, and sulphate is Epsom salts for the bath. See types of magnesium.
Which magnesium is absorbed best?
Organic forms, those bound to an acid or amino acid such as citrate and glycinate, are generally better absorbed than inorganic forms such as oxide. In a 60-day controlled trial at the University of Reading, citrate led to the highest blood magnesium levels and an amino acid chelate also beat oxide.
Beyond that, the differences between good forms are smaller than marketing suggests. Taking magnesium every day, in a form you tolerate, matters more than picking the “perfect” type. Splitting larger doses and taking them with food can also help. See how long magnesium takes to work.
Best magnesium by goal
| Your goal | Best first choice | Read more |
|---|---|---|
| An evening wind-down | Glycinate, or a glycinate and citrate blend | Magnesium for sleep |
| Stress and tiredness | Glycinate | Magnesium for anxiety |
| Constipation | Citrate | Magnesium for constipation |
| Muscle cramps | Glycinate or citrate | Magnesium for cramps |
| Focus and memory | L-threonate | Magnesium L-threonate |
| Menopause | Glycinate | Magnesium for menopause |
Magnesium contributes to the reduction of tiredness and fatigue, normal psychological function, normal functioning of the nervous system and normal muscle function, whichever form you take. Not sure when to take yours? See the best time to take magnesium.
Can you take different types of magnesium together?
Yes. Many supplements combine forms, such as glycinate with citrate, to balance gentleness and absorption. Some people take threonate in the morning and glycinate in the evening. The key is to add up the elemental magnesium from everything you take and stay within safe limits.
How much magnesium should you take?
The NHS says adults need 300mg a day (men) or 270mg a day (women), and most people can get this from a varied diet. If you take a supplement, 400mg a day or less is unlikely to cause harm. Taking more than 400mg for a short time can cause diarrhoea. Start lower, around 100 to 200mg, and increase if needed. See signs of magnesium deficiency.
Side effects and who should check first
The most common side effects are loose stools, nausea and stomach cramps, more likely with citrate and oxide or at high doses. Speak to your GP or pharmacist before taking magnesium if you:
- have kidney disease, as your body may not clear magnesium properly
- take antibiotics such as tetracyclines or quinolones (take them at least 2 hours before or 4 to 6 hours after magnesium)
- take osteoporosis medicines such as bisphosphonates, which need spacing from magnesium
- take diuretics or long-term acid-reducing medicines (PPIs)
- are pregnant or breastfeeding
FAQs
Which is better, magnesium glycinate or citrate?
Both are well absorbed. Glycinate is gentler on the stomach and usually preferred for evenings and stress. Citrate has a mild laxative effect, so it suits people prone to constipation.
Is magnesium glycinate or threonate better for sleep?
Glycinate is the usual first choice for an evening routine and is cheaper. Threonate has one industry-funded trial showing better sleep scores, but it contains far less magnesium per dose.
Is magnesium bisglycinate the same as glycinate?
Yes. Bisglycinate describes how magnesium glycinate is made, with each magnesium bound to two glycine molecules. The names are used interchangeably.
What is the most absorbable form of magnesium?
Organic forms such as citrate and glycinate are absorbed better than oxide. In one controlled trial, citrate raised blood levels the most. Taking it daily matters more than the exact form.
Which magnesium is best for constipation?
Magnesium citrate, because it draws water into the bowel. Start low, as too much can cause diarrhoea. See your GP if constipation lasts more than a few weeks.
Is magnesium oxide any good?
It is cheap and contains a lot of magnesium by weight, but much less is absorbed and it is more likely to loosen stools. Glycinate or citrate are usually better choices.
Can I take magnesium glycinate and citrate together?
Yes. Many supplements combine them. Add up the elemental magnesium from both and keep supplements to 400mg a day or less.
Which magnesium is best for anxiety?
Most people choose glycinate because it is gentle and suits a daily routine. Magnesium contributes to normal psychological function and the normal functioning of the nervous system.
Sources
- NHS. Vitamins and minerals: magnesium.
- Walker AF et al (2003). Mg citrate found more bioavailable than other Mg preparations in a randomised, double-blind study. Magnesium Research.
- Liu G et al (2016). Efficacy and safety of MMFS-01, a synapse density enhancer, for treating cognitive impairment in older adults. Journal of Alzheimer’s Disease.
- Hausenblas HA et al (2024). Magnesium-L-threonate improves sleep quality and daytime functioning in adults with self-reported sleep problems. Sleep Medicine X.
- GOV.UK. Great Britain nutrition and health claims register.
This guide is general information, not medical advice. Evopure makes the Magnesium Glycinate Sleep Complex.
