title: "Magnesium Glycinate vs Citrate vs Malate: Which Form Actually Matters?" description: "Evidence-based guide to magnesium supplements. Compare glycinate, citrate, malate, and oxide forms. Learn elemental content, absorption rates, and which form suits your goals." date: "2026-03-29" author: "Seb" category: "Supplements" tags: ["magnesium", "sleep", "digestion", "energy", "supplementation"] affiliateDisclosure: true
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Magnesium supplements line every health food shop shelf in the UK, and they're wildly inconsistent. You'll find forms ranging from cheap oxide (basically useless) to premium threonate (cost-prohibitive for most). The problem? Your magnesium form matters far more than most people realise.
This guide cuts through the noise and tells you exactly which magnesium form suits your goal — whether that's better sleep, sustained energy, or digestive support.
Why Magnesium Form Actually Matters
Magnesium doesn't exist as a standalone mineral in supplements. It's bound to other compounds (citrate, glycinate, oxide, etc.), and this binding dramatically affects how your body absorbs and uses it.
The key variables are:
- Absorption rate: How much of the magnesium actually makes it into your bloodstream
- Elemental magnesium content: The actual amount of pure magnesium in each capsule
- Secondary effects: Whether the compound has laxative properties, CNS effects, etc.
- Cost: Premium forms cost significantly more
Most people don't check these details and end up with the wrong form for their needs.
Magnesium Glycinate: Best for Sleep and Relaxation
Elemental content: 14% (approximately 140mg per 1000mg supplement)
Why it's effective: Glycine is an amino acid with mild sedative properties. Magnesium glycinate is highly absorbable and gentle on the digestive system.
Absorption rate: Excellent (80-90%)
Secondary benefits: Glycine itself supports sleep quality and collagen synthesis. This makes it arguably the best magnesium form for evening supplementation.
Downsides: It's more expensive than citrate or oxide. You pay a premium for the sleep benefits.
Practical use: 300-400mg elemental magnesium 1-2 hours before bed. Shop on Amazon UK for brands like Bulk Powders or Nootropics Depot. A month's supply costs around £8-12.
Evidence: The combination of magnesium and glycine has shown benefits for sleep latency in several small studies. The mechanism is straightforward — both compounds individually support relaxation.
Magnesium Citrate: Best for Digestion and Energy
Elemental content: 16% (approximately 160mg per 1000mg supplement)
Why it's effective: Citrate is well-absorbed and has a mild laxative effect at higher doses. This makes it useful if you struggle with constipation.
Absorption rate: Very good (85%)
Secondary benefits: The citrate compound itself appears to have a slight energising effect (likely due to its role in the citric acid cycle). Some athletes prefer citrate around training.
Downsides: The laxative effect becomes pronounced above 400mg daily. If you're prone to loose stools, this isn't your form.
Practical use: 200-300mg for general health, up to 400-500mg if you need digestive support. It's cheaper than glycinate — typically £4-7 per month from Bulk Powders or MyProtein UK.
Evidence: Magnesium citrate is well-studied for both absorption and its laxative properties. It's commonly used in clinical settings for constipation management.
Magnesium Malate: Best for Energy and Muscle Function
Elemental content: 6-7% (lower than citrate or glycinate — roughly 60-70mg per 1000mg supplement)
Why it's effective: Malate is a compound involved in ATP production (cellular energy). Some evidence suggests magnesium malate supports muscle function and reduces fatigue in certain populations.
Absorption rate: Good (80-85%)
Secondary benefits: Malate itself may support energy production. This makes it the choice if you're taking magnesium primarily for performance, not sleep.
Downsides: Lower elemental content means you need more capsules to hit therapeutic doses. It can be more expensive per mg of elemental magnesium than citrate.
Practical use: 300-400mg daily with food. Good for athletes or anyone battling fatigue. Budget £6-10 per month.
Evidence: Limited but promising. Some studies show magnesium malate reduces muscle fatigue, though the evidence is weaker than for glycinate and sleep.
Magnesium Oxide: Cheap and Mostly Useless
Elemental content: 60% (highest elemental content, but irrelevant)
Why to avoid it: Oxide has terrible bioavailability — your body absorbs only 4% of it. You're paying for something you can't use.
The irony: Supermarket supplements often use oxide specifically because it's cheap. You might see a 250mg capsule for £2-3, but you're absorbing about 10mg. It's marketing genius and consumer deception combined.
Secondary effect: The unabsorbed oxide acts as a laxative, which is why many people taking cheap magnesium supplements develop loose stools.
Practical advice: Avoid. The slight cost saving isn't worth the wasted supplement.
Magnesium Threonate: Crosses the Blood-Brain Barrier
Elemental content: 2-3% (very low)
Why it exists: Threonate is specifically designed to cross the blood-brain barrier, making it useful for cognitive support. The marketing suggests it's "the only magnesium for the brain."
Reality check: While threonate does reach the brain effectively, this doesn't mean you need it unless you specifically want magnesium targeting your CNS. For most people, adequate general magnesium (glycinate, citrate, malate) provides sufficient brain support.
Cost: Roughly £25-40 per month — premium pricing.
Practical use: Only if you're specifically targeting cognitive decline or neurological support. For general health, glycinate does 80% of what threonate does at half the cost.
Elemental Magnesium Content: The Key Number
Don't be fooled by capsule size. A 1000mg capsule might contain only 100-160mg of actual, absorbable magnesium. Here's a quick reference:
| Form | Elemental % | Per 1000mg capsule | |------|------------|-------------------| | Glycinate | 14% | ~140mg | | Citrate | 16% | ~160mg | | Malate | 6-7% | ~60-70mg | | Oxide | 60% | 600mg (but ~5-10% absorbed) | | Threonate | 2-3% | ~25-30mg |
Always check the label for elemental magnesium content, not capsule weight.
Practical Recommendations by Goal
For better sleep: Magnesium glycinate, 300-400mg, 1-2 hours before bed. £8-12/month.
For sustained energy during training: Magnesium citrate or malate, 200-300mg with breakfast or pre-training. £4-8/month.
For digestive support: Magnesium citrate, 300-500mg in the evening. £4-7/month.
Budget-conscious and sleeping fine: Magnesium citrate covers most bases at low cost. £4-7/month.
Maximising everything: Magnesium glycinate in the evening (sleep), citrate with breakfast (energy and digestion). Total: £12-18/month.
Dosing Protocol
Most adults need 400-500mg elemental magnesium daily (though RDA is 400mg for men). Split doses are better than single doses.
- Glycinate: Take with or without food, preferably 1-2 hours before bed
- Citrate: Take with breakfast or lunch to avoid evening laxative effects
- Malate: Take with food, ideally with carbohydrates to support energy production
Magnesium can interact with antibiotics and some medications. If you're on prescription drugs, check with your GP before starting supplementation.
UK Brands Worth Buying
- Bulk Powders: Excellent value, all major forms available on Amazon UK, fast delivery
- Nootropics Depot: Premium quality, available on Amazon UK, reliable testing, higher cost
- MyProtein: Good general source, available on Amazon UK, frequent discounts, wide selection
- PhD Nutrition: UK-based, available on Amazon UK, quality assured, pricier but reliable
Avoid supermarket own-brand magnesium — it's almost always oxide.
The Bottom Line
Magnesium form genuinely matters. Glycinate is the best choice for sleep and recovery (and worth the premium). Citrate is your best value option for general health and has the bonus of digestive support. Malate works well if energy is your priority. Avoid oxide entirely — the savings aren't worth the poor absorption.
Start with one form aligned to your primary goal. Most people benefit from either glycinate (evening) or citrate (morning) at under £10 per month. Budget a few weeks to assess the effect — magnesium doesn't produce dramatic overnight changes, but consistent supplementation improves sleep quality and energy stability over 4-6 weeks.