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What is the best magnesium for leg cramps and restless legs?
For leg cramps and restless legs, magnesium glycinate, 300mg elemental, is the form to try, evidence stated plainly: the nocturnal cramp trials were negative, the restless legs review found evidence insufficient, and low iron is what a GP should check.
- Negativethe nocturnal leg cramp trials with magnesium oxide
- Insufficientthe evidence for magnesium in restless legs, per the 2019 review
- Ironthe factor with real evidence in restless legs
- 22pa day for the worked example
Worked example: Futuro Labs Magnesium Glycinate on Amazon UK, 180 capsules for £19.99. Label breakdown. Restless legs that disturb sleep most nights is a GP matter, and the first test is iron.
Leg cramps: what the trials found
Roguin Maor's 2017 randomised trial gave magnesium oxide nightly to adults with frequent nocturnal leg cramps and found no benefit over placebo; Garrison's 2020 Cochrane review pooled that and the earlier trials and concluded magnesium is unlikely to help idiopathic cramps. The form in most of those trials was oxide, the poorly absorbed one, which is a fair criticism of the studies and not a licence to promise anything. Where magnesium plausibly helps cramps is in people whose intake was low, and a well absorbed form is the honest way to test that.
Restless legs: a different problem with a different answer
Restless legs syndrome is an urge to move the legs, worse in the evening and at rest, relieved by movement. It is not a cramp. Marshall's 2019 systematic review found the evidence for magnesium in restless legs and periodic limb movements insufficient to support it; the nutrient with real evidence is iron. The international guidelines summarised by Allen and colleagues in 2018 recommend checking iron status, specifically ferritin, in anyone with restless legs, because low iron stores drive the condition and treating them helps. That is a GP conversation and a blood test, not a magnesium decision. Restless legs that disturb sleep most nights, or start in pregnancy, are worth that appointment.
| Problem | Evidence for magnesium | What actually has evidence | What to do |
|---|---|---|---|
| Nocturnal leg cramps | Negative trials, mostly oxide | Stretching before bed; correcting a low intake | 300mg elemental as glycinate with the evening meal for a month |
| Cramps in or after training | Helps where intake was low | Sodium and fluid in long hot sessions; managing fatigue | Magnesium daily, electrolytes on heavy days |
| Restless legs | Insufficient (2019 review) | Iron status; treating low ferritin | GP and a ferritin test first |
| Both together | As above for each | As above for each | Glycinate for the cramp side while the iron question is answered |
Which magnesium, if you take it for the cramp side
Glycinate, 300mg elemental, with the evening meal, for a month. The worked example, Futuro Labs Magnesium Glycinate, gives that from 1500mg chelated bisglycinate in 2 capsules, 80% NRV, low laxative effect, from a vegan capsule made in the UK under GMP and BRC certification and third-party tested for heavy metals and microbiology, 180 capsules for £19.99, 22p a day. It is the form the negative trials did not use, which is the fairest test available of whether your cramps were an intake problem. It carries no cramp or restless legs claim, because none is authorised; the claims are normal muscle function, electrolyte balance and the normal functioning of the nervous system. If the restless legs are the bigger problem, book the GP before the bottle arrives.
What to check on the label
- Elemental magnesium 300mg per serving, 80% NRV printed.
- Glycinate first, not oxide, which is the form that failed the cramp trials.
- No cramp or restless legs claims; none are authorised.
- A ferritin test through a GP if restless legs are the main problem.
- Cost per day under 25p.
The worked example: Futuro Labs Magnesium Glycinate
Futuro Labs Magnesium Glycinate is the worked example for the cramp side of the question: 300mg elemental per 2 capsules (80% NRV) from chelated bisglycinate, the well absorbed form the negative trials did not use, vegan, UK made, third-party tested, 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
Does magnesium help restless legs?
The 2019 systematic review found the evidence insufficient. Iron status is the factor with real evidence; a GP can check ferritin.
What is the best magnesium for restless legs at night?
If you take one, glycinate at 300mg elemental with the evening meal, with the caveat that the evidence is insufficient and iron matters more.
Does magnesium stop leg cramps at night?
The randomised trials, mostly with magnesium oxide, found no benefit over placebo. Correcting a low intake with a well absorbed form is still the sensible first step.
Is restless legs a magnesium deficiency?
Not as a rule. Low iron stores are the recognised driver; low magnesium intake can cause cramps and twitching, which are different things.
Should I see a GP about restless legs?
Yes if it disturbs sleep most nights, started in pregnancy, or comes with other symptoms. The first test is iron.
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
- Marshall NS, Serinel Y, Killick R, et al. Magnesium supplementation for the treatment of restless legs syndrome and periodic limb movement disorder: a systematic review. Sleep Medicine Reviews 2019;48:101218. PubMed record
- Allen RP, Picchietti DL, Auerbach M, et al. Evidence-based and consensus clinical practice guidelines for the iron treatment of restless legs syndrome/Willis-Ekbom disease in adults and children. Sleep Medicine 2018;41:27-44. 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