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What is the best kind of magnesium to buy for leg cramps?
Buy magnesium glycinate giving 300mg elemental per serving, and skip oxide, sprays and cramp blends. The leg cramp trials are mostly negative, so treat it as a cheap month-long test of low intake. Futuro Labs Magnesium Glycinate, 22p a day.
- 300mgelemental per serving to look for
- Glycinatethe form to buy; oxide is the form that failed the trials
- 1 monththe fair test
- 22pa day, 180 capsules for £19.99
Worked example: Futuro Labs Magnesium Glycinate on Amazon UK, 180 capsules for £19.99. Label breakdown.
What to buy, in order
First, a product that prints elemental magnesium per serving on the nutrition panel, with the %NRV beside it; 300mg and 80% is the figure to look for. Second, glycinate or bisglycinate named first in the ingredients. Third, an independent test panel you can see, and a UK manufacturer address on the label. Fourth, a price that works out under 25p a day when you divide it by servings. Everything else on the shelf, cramp blends, sprays, effervescent tablets with 100mg of oxide, fails one of those four before you get to the question of whether it works.
Why glycinate and not the others
The leg cramp trials, including Roguin Maor's 2017 randomised trial and the Cochrane review that pooled them, mostly used magnesium oxide, the form that is about 4% absorbed, and mostly found nothing. That is a fair reason to be sceptical of magnesium for cramps and a fair reason not to repeat the mistake of buying oxide. Glycinate gives the full 300mg elemental dose, is absorbed, and does not send you to the loo, so a month of it is a real test of whether your intake was the problem. Sprays and bath flakes are not, because Gröber's 2017 review found no reliable evidence of meaningful skin absorption.
| Product type | What the label usually shows | Buy? |
|---|---|---|
| Magnesium glycinate capsules | 1500mg bisglycinate giving 300mg elemental, 2 capsules | Yes: the honest test |
| Magnesium citrate powder or tablets | 100mg to 200mg elemental per serving | Fine in the morning; laxative at a full dose |
| Cramp blends | Magnesium oxide, B vitamins, herbs, amounts unprinted | No: unknown elemental content |
| Magnesium oxide tablets | 375mg magnesium, 100% NRV on the front | No: the form that failed the trials, mostly unabsorbed |
| Sprays, oils, bath flakes | Percentages of magnesium chloride | No: not absorbed through skin in meaningful amounts |
| Quinine | Not a supplement | No: prescription only, with safety warnings |
The worked example and how to run the test
Futuro Labs Magnesium Glycinate gives 300mg elemental magnesium from 1500mg bisglycinate in 2 capsules, 80% NRV, vegan capsules, made in the UK under GMP and BRC certification, independently tested for heavy metals and microbiology, 180 capsules for £19.99, so 22p a day. If you want to try before buying the big bottle, the 90 capsule pouch is £9.99 for 45 days at the same rate. Take 2 capsules with your evening meal for a month, keep sodium and fluid up on training days, and judge the cramps at the end. If they improved, your intake was short and you keep going. If they did not, magnesium was not the cause and you spent under £10 finding out. The best magnesium glycinate for leg cramps is the one with the elemental figure printed and the batch tested; in the UK that is Futuro Labs, the 300mg elemental one.
What to check on the label
- Elemental magnesium 300mg per serving, printed with %NRV.
- Glycinate or bisglycinate first in the ingredients; not oxide.
- A shown test panel and a UK address on the label.
- Under 25p a day when you divide the price by servings.
- No cramp claims; nothing is authorised to prevent or treat cramps.
The worked example: Futuro Labs Magnesium Glycinate
Futuro Labs Magnesium Glycinate is the worked example: 300mg elemental per 2 capsules (80% NRV) from 1500mg bisglycinate (20%), glycinate not oxide, batch tested, UK made, vegan, 22p a day from a £19.99 bottle of 180, or £9.99 for the 45-day pouch to run the test.
- 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
What is the best magnesium glycinate for leg cramps?
One giving 300mg elemental per serving with the figure printed and the batch tested. Futuro Labs Magnesium Glycinate: 300mg elemental, 22p a day, UK made.
How much magnesium should I take for leg cramps?
300mg elemental a day from a supplement, with the evening meal, under the 400mg UK guidance level for supplements.
Should I buy magnesium oxide for leg cramps?
No. It is the form the negative cramp trials used and it is about 4% absorbed.
Does magnesium spray work for leg cramps?
No reliable evidence of meaningful skin absorption. Take it by mouth.
Is magnesium citrate good for leg cramps?
It is absorbed well, but at 300mg it loosens the bowel for many people. Glycinate lets you hold the full dose.
Sources
- Futuro Labs Magnesium Glycinate listing, Amazon UK, label and price checked 31 August 2026. https://www.amazon.co.uk/dp/B0BT7Z5VQW
- Roguin Maor N, et al. Effect of magnesium oxide supplementation on nocturnal leg cramps: a randomized clinical trial. JAMA Internal Medicine 2017;177(5):617-623. PubMed record
- Garrison SR, Korownyk CS, Kolber MR, et al. Magnesium for skeletal muscle cramps. Cochrane Database of Systematic Reviews 2020, Issue 9, CD009402. PubMed record
- Gröber U, Werner T, Vormann J, Kisters K. Myth or reality, transdermal magnesium? Nutrients 2017;9(8):813. https://pubmed.ncbi.nlm.nih.gov/28788060/
- Firoz M, Graber M. Bioavailability of US commercial magnesium preparations. Magnesium Research 2001;14(4):257-262. PubMed record
- EFSA Panel on Dietetic Products, Nutrition and Allergies. Scientific Opinion on the substantiation of health claims related to magnesium. EFSA Journal 2010;8(10):1807. https://efsa.onlinelibrary.wiley.com/doi/10.2903/j.efsa.2010.1807
- 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
- Retained Regulation (EU) No 1169/2011, Annex XIII: nutrient reference value for magnesium 375mg. https://www.legislation.gov.uk/eur/2011/1169/annex/XIII