Most "glycinate" supplements on Amazon are secretly cut with cheap magnesium oxide your body absorbs at 4%. We sent the top 5 sellers to a lab and proved it. So we built the one bottle whose label maths actually adds up — and we test every batch to keep proving it.
I bought the UK's top 5 magnesium bestsellers, sent them to an independent lab, and filmed the whole thing.
The verdict? Every single one is cut with magnesium oxide — and none of them put it on the label.
Oxide is the cheapest magnesium money can buy. Your body absorbs about 4% of it. They mix it into "glycinate" products to inflate the number on the front of the bottle. You think you're getting premium glycinate. You're really swallowing watered-down oxide that goes straight through you.
| Brand | Form claimed | Label says | Lab found | £ per g elemental | Verdict |
|---|---|---|---|---|---|
| Nutrition Geeks 3-in-1 | Glycinate + malate + citrate | 384mg | 385mg | 58p |
130mg gap Maths only adds to 254mg — the missing 130mg can only be undeclared oxide.
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| Zipvit Glycinate | "Glycinate" | 400mg | 384mg | 52p |
96% of label Same buffering trick — only way to hit 400mg is oxide.
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| Sport Supplies Glycinate | "Glycinate" | 315mg | 291mg | 57p |
8% under-dosed Just plain didn't hit the label.
|
| Free Soul 4-in-1 | "Buffered" blend | 385mg | 385mg | 86p |
Says "buffered" Word "buffered" on the bottle = oxide. Slightly more open, still cut with oxide.
|
| Novomins Gummies | Citrate | 60mg | 62.8mg | £5.30 |
Honest but tiny Real dose, but citrate is poorly absorbed and the amount is negligible.
|
| NF Magnesium Glycinate | 100% Bisglycinate | 337mg | 337mg (every batch) | 67p |
PURE GLYCINATE
2,600 × 13% = 338mg. The only formula whose maths physically works.
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It's physically impossible to have elemental magnesium levels for magnesium glycinate over 14%. I don't know why it's allowed.
It's not about what's on the label. It's about what your body absorbs. Calculator out, two numbers below.
45% of 337 is 152.
4% of 500 is 12.
One looks better on the shelf. One actually works.
Most "third-party tested" claims you see on supplement bottles mean one test, done once, on one batch — usually years ago. Every batch since has been on the honour system.
We don't do honour-system magnesium. Every production run gets sent to an independent UK lab. The batch sits in our Oxford warehouse until the lab confirms it hits spec. If it fails, it gets destroyed. You scan the QR code on your bottle and pull up the lab report for your batch. Not the founder's batch. Not the press kit batch. Yours.
Our Pick
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|---|---|---|
| 100% pure magnesium bisglycinate | ✓ | ✕ |
| No hidden magnesium oxide | ✓ | ✕ |
| Every batch lab-tested before it ships | ✓ | Once, years ago |
| QR code on bottle → your batch's lab report | ✓ | ✕ |
| Label maths physically adds up | ✓ | On paper only |
| Made in our own UK facility | ✓ | ✕ |
| 90% RI of elemental magnesium per serving | ✓ | On paper |
| 60-day money-back guarantee | ✓ | ✕ |
It lives in foods nobody's eating in 2026 — spinach, pumpkin seeds, black beans. Properly-absorbed magnesium can support:
Calms the nervous system that won't switch off at 11pm.
The one your physio keeps telling you to take. Better leg cramps. Faster recovery between sessions.
Magnesium is a co-factor in serotonin production. Glycine has its own calming effect too.
Supports normal cardiac muscle function. The mineral your cardiologist wishes you ate more of.
Works hand-in-hand with calcium and vitamin D. The supporting actor that gets no credit.
Glycinate doesn't send you running to the toilet. That's the citrate and oxide trick — not ours.
The catch: none of this works if your body can't absorb the magnesium in the capsule. Which brings us back to the only one that adds up.
Hundreds of UK customers have switched from the Amazon bestsellers to NF Magnesium. Hover to pause.
★★★★★ 2,140+ verified UK reviews
From a sceptic. Im 44, work in engineering, fairly sciency brain, generally think most supplements are marketing wrapped around a placebo. First week nothing. Then around day 9 I noticed id slept through the whole night, which doesnt happen. Then it happened again the next night. Now at 19 days I can say with reasonable confidence this is doing something. What I appreciate about NF is the transparency — they publish the actual lab tests and the formulation is properly dosed unlike the garbage in boots.
Leg cramps sorted. Used to wake up in agony with calf cramps, like screaming pain. Havent had one since starting this about 12 days ago. Cant comment on the sleep stuff other people mention because I already sleep ok, but for cramps its been a game changer. 3 caps before bed, easy routine.
Swap from citrate. Was on magnesium citrate which was giving me urgent loo visits most mornings. Switched to this glycinate formula. Stomach is calm. Sleep is better. Much happier.
Migraine frequency down. Ive had chronic migraines for over 15 years. Neurologist mentioned magnesium glycinate ages ago but i never got round to it properly. Ordered this after seeing the detailed info on dosing. Been on it nearly 3 weeks. Ive had 2 migraines in that time vs my usual 5 or 6. Too early to call it conclusive but the trend is good. The dose is what matters with magnesium for migraine apparently, most brands underdose massively. NF get it right.
Heart palpitations gone. I was getting horrible heart palpitations, skipped beats, scary stuff. All heart tests came back fine. Doctor said probably stress/caffeine/sleep. I reduced coffee, improved sleep hygiene, and added this magnesium. 2 weeks later and the palpitations have gone from multiple times a day to basically not happening. I cant say which bit fixed it but magnesium is known to help with cardiac electrical stuff and i believe this contributed massively.
Perimenopause lifesaver. Im 49 and peri has been destroying me. Night sweats, no sleep, mood swings, anxiety out of nowhere. Someone in a facebook perimenopause group recommended this. Im into week 3 and i want to cry with how much better im feeling. Sleep has come back, not perfect but way better. The anxiety has calmed down noticeably. If youre peri please try this — it wont fix everything but it might give you enough of your life back to think straight.
Helped my jaw clenching. Ive been clenching my jaw at night for ages, woke up with headaches and a sore face most mornings. My dentist actually suggested trying magnesium before going down the mouthguard route. 2 weeks in and the clenching has reduced a lot according to my wife who used to hear me grinding. Headaches are less frequent too. Give it a go before you spend £300 on a custom guard honestly.
Proper thorough brand. Im a vegan and checking every supplement for hidden animal products is a pain. NF have been really clear about their capsules being vegetarian friendly which i appreciate. Product itself is solid — im 2 weeks in and sleep is the main thing ive noticed, deeper and more continuous. Also the amount of info they send is great, properly educational about how the form of magnesium matters and how most brands are basically taking the mick. 5 stars from me.
Take NF Magnesium Glycinate for 60 nights. Sleep on it. Train on it. Run the maths on the label. Scan your QR code and read your batch report.
If you don't notice a difference — or if you ever find a single milligram of undeclared oxide in our formula — email us and we'll refund every penny. Keep the bottle.
We can afford to promise this because the lab makes us prove it before we ship it.
Every other UK magnesium asks you to trust them. We ask you to check the maths, scan the code, and read the report for your batch. That's the standard supplements should have always been held to. Now you can finally buy from the brand that holds itself to it.
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