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What to look for when buying magnesium tablets?
When buying magnesium tablets, check the form first: most UK tablets are compressed oxide, about 4% absorbed, printing 100% NRV. Look for the elemental line, the ingredients order and a test panel; usually the answer is to buy bisglycinate capsules.
- Oxidethe form inside most UK magnesium tablets
- About 4%of oxide is absorbed
- 100% NRVthe impressive number the tablet prints anyway
- 22pa day for the capsule alternative
The capsule alternative: Futuro Labs Magnesium Glycinate on Amazon UK, 180 capsules for £19.99. Label breakdown. The wider tablet-versus-format question is on the best magnesium tablets for the gym page.
Why tablets need their own buying rules
Tablets are powder compressed under force with binders, coatings and disintegrants, and the format quietly selects the form. Oxide compresses beautifully, is 60% magnesium by weight, and lets a small tablet print 375mg and 100% NRV; bisglycinate is bulky and mostly refuses to be a small tablet at a real dose. So the tablet aisle skews oxide, the form Firoz and Graber measured at around 4% absorption and the form the negative cramp trials used. A tablet buyer needs one extra reflex the capsule buyer does not: assume oxide until the label proves otherwise.
The four checks on a tablet label
First, the form, named in the ingredients: oxide means put it back, citrate is legitimate, and a genuine bisglycinate tablet will be large and honest about needing two or three. Second, the elemental line with %NRV, remembering that oxide's impressive 100% is elemental too; the number does not rescue the absorption, so the form check comes first for a reason. Third, the excipient list: tablets carry more binders, coatings and polishing agents than capsules, none of which are dangerous, all of which signal how much of the tablet is not magnesium; a shorter list is a better sign. Fourth, a shown third-party test panel, the same requirement as everywhere else on this site, because compressed or encapsulated, nobody tested it before sale but the brand.
| Label line | What it usually means on a tablet | Verdict |
|---|---|---|
| Magnesium 375mg, 100% NRV | Oxide; the number is real, the absorption is not | Put it back |
| Magnesium citrate 500mg providing 80mg magnesium | Honest citrate at a small dose | Fine in the morning; two or three needed for a real dose |
| Magnesium bisglycinate, large tablet, 2 to 3 per serving | A genuine glycinate accepting its bulk | Acceptable; compare cost per day with capsules |
| Slow release or coated | A coating on top of whatever form is inside | The form still decides; check it |
| A blend of three forms, no split | Oxide-heavy behind the blend | Put it back |
The usual conclusion, and when a tablet is still right
Run the four checks and most tablet shelves empty themselves, which is why the practical answer to what to look for when buying magnesium tablets is a capsule: Futuro Labs Magnesium Glycinate gives 300mg elemental from 1500mg bisglycinate at 20% in 2 capsules, 80% NRV printed, test panels shown, vegan, made in the UK under GMP and BRC certification, 180 capsules for £19.99, 22p a day. A tablet earns its place in two cases: an effervescent citrate for someone who cannot swallow capsules, taken in the morning with the sodium checked, and a small citrate tablet used deliberately for regularity. For the daily 300mg that training asks for, the capsule wins on form, dose and price.
What to check on the label
- The form named in the ingredients: assume oxide until proven otherwise.
- The elemental line with %NRV, read after the form, not instead of it.
- A short excipient list; tablets carry more binders than capsules.
- A shown test panel, same as any format.
- Cost per day against 22p for 300mg elemental as glycinate capsules.
The worked example: Futuro Labs Magnesium Glycinate
Futuro Labs Magnesium Glycinate is the capsule this page lands on: 300mg elemental per 2 capsules (80% NRV) from bisglycinate 20%, panels shown, vegan, UK made, 22p a day from a £19.99 bottle of 180.
- Elemental magnesium per serving
- 300mg (80% NRV)
- Form
- magnesium bisglycinate 20%
- Serving
- 2 capsules a day
- Bottle
- 180 capsules, 90 days
- Price
- £19.99 (22p a day)
- Capsule
- vegetarian shell, vegan product
Questions people also ask
Are magnesium tablets as good as capsules?
The format matters less than the form, but tablets are usually oxide and capsules are where the glycinates live. Check the ingredients line first.
What is the best magnesium tablet in the UK?
A citrate if it must be a tablet, taken in the morning. For daily intake, bisglycinate capsules at 300mg elemental beat every tablet checked.
Why do magnesium tablets say 100% NRV?
Because oxide is 60% magnesium by weight, so a small tablet can carry 375mg elemental on paper. About 4% of it is absorbed.
Are slow release magnesium tablets better?
The coating does not change the form inside. A slow release oxide is still oxide; check the ingredients.
Can I cut magnesium tablets in half?
Uncoated ones, yes, to split a dose. Coated or slow release tablets are designed to stay whole.
Sources
- Futuro Labs Magnesium Glycinate listing, Amazon UK, label and price checked 31 August 2026. https://www.amazon.co.uk/dp/B0BT7Z5VQW
- Firoz M, Graber M. Bioavailability of US commercial magnesium preparations. Magnesium Research 2001;14(4):257-262. PubMed record
- Walker AF, Marakis G, Christie S, Byng M. Mg citrate found more bioavailable than other Mg preparations in a randomised, double-blind study. Magnesium Research 2003;16(3):183-191. PubMed record
- Retained Regulation (EU) No 1169/2011, Annex XIII: nutrient reference value for magnesium 375mg. https://www.legislation.gov.uk/eur/2011/1169/annex/XIII
- Expert Group on Vitamins and Minerals. Safe Upper Levels for Vitamins and Minerals. Food Standards Agency, 2003 (magnesium guidance level 400mg a day from supplements). https://cot.food.gov.uk/sites/default/files/vitmin2003.pdf
- The Food Supplements (England) Regulations 2003 (food supplements are regulated as foods in the UK). https://www.legislation.gov.uk/uksi/2003/1387/contents/made