Types of Magnesium: All 8 Forms Compared — Which Is Best in the UK? (2026)
In the UK, a bisglycinate or a citrate covers most needs, kept at or under EFSA’s 250 mg a day from supplements. UK labels show magnesium in mg and as % NRV (100% = 375 mg). GB law allows all 8 forms in supplements, L-threonate only since 2026. Some UK “bisglycinate” products also contain oxide, so read the words in brackets.
Glycinate
Solgar Magnesium Glycinate
240 mg in 2 capsules (64% NRV), £0.53 a day at Solgar’s UK price
Check priceCitrate
Lamberts MagAsorb Magnesium Citrate 150 mg
150 mg a tablet, £0.26 per 300 mg, the lowest cost per mg at UK list prices
Check priceWhich Form for Which Goal, With a UK Product
| Goal | What was tested | On Amazon.co.uk |
|---|---|---|
| Sleep | Bisglycinate: one 2025 trial (250 mg) found a small benefit over placebo. No form is proven best. | Solgar Magnesium Glycinate |
| Constipation | Oxide or citrate. We found no oxide product to recommend here, so citrate; take one tablet to stay near EFSA’s limit. | Solgar Magnesium Citrate |
| Leg cramps | Weak evidence. For night cramps in older adults a Cochrane review found magnesium unlikely to help; one positive trial used oxide. In pregnancy, one trial found fewer cramps on 300 mg of bisglycinate a day; ask your midwife first. | No product: we found no UK oxide product to recommend |
| Low intake from food | Citrate: the most magnesium per pound at the UK list prices we found. | Lamberts MagAsorb Magnesium Citrate 150 mg |
| Stress or anxiety | No form is proven. Only small studies; a low-dose bisglycinate keeps well under the limits. | Lamberts Gentle Magnesium Bisglycinate |
| Migraine | Trials used up to 600 mg a day, above the NHS and EFSA figures. Talk to your GP first. | No product: only with your GP’s advice |
Reading a UK Magnesium Label
- The magnesium line is the dose. It shows mg and % NRV, where 100% NRV is 375 mg. Our glycinate pick is 64% NRV.
- Read the words in brackets. “Magnesium (as bisglycinate)” is one form. Three UK listings we read that name bisglycinate also contained magnesium oxide. That is legal if the label says so, but you pay glycinate prices for part oxide.
- Mind the limits. EFSA’s safe limit for magnesium from supplements is 250 mg a day; the NHS says 400 mg or less is unlikely to cause harm. A 2-tablet citrate serving of 400 mg (107% NRV), like Solgar Magnesium Citrate, is over EFSA’s figure; one tablet is not.
All 8 Magnesium Forms Under UK Law
| Form | Magnesium by weight | What it is and what it is for | In the UK |
|---|---|---|---|
| Glycinate | ~14% | Glycine-bound magnesium, sold as bisglycinate. People pick it to spare the stomach; in a 12-person trial it was better tolerated than oxide. One 2025 trial tested it for sleep. | Allowed as magnesium bisglycinate. Three UK listings we read that say bisglycinate also held oxide. On Amazon.co.uk: Solgar Magnesium Glycinate. |
| Citrate | ~16% | The citric-acid salt and the most common form on shelves. More was absorbed than from oxide in small studies. High doses act as a laxative. | Allowed. Lamberts MagAsorb was the lowest cost per mg at UK list prices. On Amazon.co.uk: Lamberts MagAsorb Magnesium Citrate 150 mg. |
| Chloride | ~12% | Sold as tablets and as “magnesium oil” for the skin. Swallowed, it absorbed better than oxide in one small study; uptake through skin is unproven. Often linked to diarrhoea. | Allowed. We have not reviewed a chloride product on Amazon.co.uk; if you buy one, check the mg and % NRV on the magnesium line. |
| Malate | ~15% | The malic-acid salt, marketed for energy and fibromyalgia. A 2019 review found it made little or no difference to fibromyalgia pain. | Allowed. We have not reviewed a malate product on Amazon.co.uk. Some are blends, so read the words in brackets. |
| Taurate | ~9% | Taurine-bound magnesium, marketed for the heart. The idea rests on a 1996 theory paper; no human trial of this form found. | Allowed. We have not reviewed a taurate product on Amazon.co.uk; with about 9% magnesium, expect several capsules per serving. |
| L-Threonate | ~7% | Designed to reach the brain, which was shown in rats. Two small human trials, funded by the maker, reported memory gains. Only about 7% is magnesium. | Added in 2026: in force in Scotland and Wales from 5 March and in England from 12 August. On Amazon.co.uk: Double Wood Magnesium L-Threonate (imported). |
| Oxide | ~60% | Cheapest, and the most magnesium by weight, but about 4% was absorbed in one US study. Works as a laxative and an antacid. | Allowed. Some UK “bisglycinate” products mix it in; read the words in brackets. |
| Sulfate | ~10% | Epsom salts, meant for the bath. Swallowed, it is a strong laxative. Hospitals give it by drip. | Allowed (spelled “sulphate” in UK law). Sold in the UK mostly as Epsom salts for the bath; we have not reviewed a supplement. |
For how each form absorbs and what the studies found, see the US forms page.
Which Form Costs Least in the UK?
| Product | Form | Per 300 mg | Buy |
|---|---|---|---|
| Lamberts MagAsorb Magnesium Citrate 150 mg | citrate | £0.26 | Check price |
| Solgar Magnesium Citrate | citrate | £0.39 | Check price |
| Lamberts Gentle Magnesium Bisglycinate | bisglycinate | £0.40 | Check price |
| Solgar Magnesium Glycinate | bisglycinate | £0.67 | Check price |
At list price, citrate is the cheaper everyday form. We could not price three imported products, so they are listed here without a cost: Doctor’s Best High Absorption Magnesium (glycinate lysinate chelate, 200 mg in 2 tablets), Natural Calm (Natural Vitality) (a citrate powder) and Double Wood Magnesium L-Threonate (L-threonate, about 144 mg in 4 capsules).
Safety and Medicines
- If you have kidney disease, ask your doctor before you take magnesium. Weak kidneys cannot clear the extra, so it can build up.
- Antibiotics: take tetracyclines (such as doxycycline) or quinolones (such as ciprofloxacin) at least 2 hours before or 4 to 6 hours after magnesium (US NIH).
- The NHS says more than 400 mg of magnesium for a short time can cause diarrhoea.
Frequently Asked Questions
Which magnesium should I buy in the UK?
Look at the magnesium line first: mg and % NRV. For most adults, a bisglycinate such as Solgar Magnesium Glycinate (240 mg, 64% NRV) or a citrate such as Lamberts MagAsorb Magnesium Citrate 150 mg (the lowest cost per mg at UK list prices) is enough. Keep supplements at or under EFSA’s 250 mg a day unless your GP says otherwise.
Is magnesium bisglycinate the same as glycinate?
Yes. Bisglycinate is magnesium bound to two glycines, which is what “glycinate” supplements contain. UK law lists it as magnesium bisglycinate.
Is magnesium L-threonate legal in UK supplements?
Yes, since 2026. Magnesium L-threonate was added to the GB list of minerals allowed in supplements: in force in Scotland and Wales from 5 March 2026 and in England from 12 August 2026.
What does % NRV mean on a magnesium label?
It is the share of the nutrient reference value, 375 mg of magnesium. A label that says 64% NRV gives 240 mg. NRV is a labelling figure, not a dose you need from pills: most of your magnesium comes from food.
Which form causes the least diarrhoea?
The US NIH lists carbonate, chloride, gluconate and oxide as the forms most often linked to diarrhoea; glycinate is not on that list. The NHS says more than 400 mg of magnesium for a short time can cause it, whatever the form.
Related Guides
- Best magnesium supplement in the UK · how much magnesium per day in the UK
- US forms page (every study behind the form facts) · glycinate vs citrate
Sources
- The Nutrition (Amendment etc.) (EU Exit) Regulations 2019, Schedule 2: substances allowed in food supplements, as amended; read October 15, 2026.
- US NIH Office of Dietary Supplements. Magnesium fact sheet for health professionals (absorption, diarrhoea, medicines).
- Firoz M, Graber M. Bioavailability of US commercial magnesium preparations. Magnes Res. 2001. PubMed 11794633.
- Studies behind the form descriptions: Schuette 1994 (glycinate vs oxide), PubMed 7815675; Schuster 2025 (sleep), PubMed 40918053; Supakatisant 2015 (pregnancy cramps), PubMed 22909270; Ferreira 2019 (fibromyalgia), PubMed 31150373; McCarty 1996 (taurate), PubMed 8692051; Slutsky 2010 (L-threonate in rats), PubMed 20152124.
- NHS. Vitamins and minerals: others (magnesium). EFSA. Tolerable Upper Intake Levels (magnesium). GB nutrient reference values.
- Products: Amazon.co.uk listings and Solgar and Lamberts UK websites, read October 15, 2026.