Magnesium vs Potassium for Cramps: Partners, Not Rivals
Same contraction ballet, opposite shopping advice: magnesium is the gap you supplement, potassium the mineral UK products cap on purpose. The full electrolyte decode, the safety line, and the honest cramp protocol.
At a glance
- Partners, not rivals: both are contraction electrolytes with muscle-function claims
- The route split: magnesium — supplement the gap · potassium — food first, by design
- Safety line: potassium supplements + kidney issues/BP meds = pharmacist first
- Magnesium pick: Futuro Labs Magnesium Glycinate — 300mg elemental, £19.99 / 90 days
Two electrolytes, one contraction — and opposite shopping advice
Muscle contraction is an electrolyte ballet: sodium and calcium drive the contraction stroke, potassium resets the electrical state, magnesium gates calcium and lets the fibre relax — which is why cramp conversations keep circling this pair, and why both hold authorised muscle-function claims (magnesium adding electrolyte balance explicitly). But the two minerals earn opposite buying advice. Magnesium's UK story is a supply gap — average intakes under the 375mg NRV — with a wide safety margin, making a stated 300mg elemental supplement the rational fix. Potassium's story is the reverse: abundant in ordinary food, tightly policed in blood because the heart depends on the band, and therefore deliberately conservative in UK supplement doses. Same ballet, different tickets.
The food-first potassium plan (and who must ask first)
Hitting potassium through dinner is easy enough that supplements rarely earn a place: a jacket potato, a tin of beans, a banana, yoghurt, oily fish and a pile of greens between them cover serious ground daily. The must-ask list is short and non-negotiable — reduced kidney function, or regular use of blood-pressure medications in the ACE-inhibitor/ARB families or potassium-sparing diuretics like spironolactone — because those situations turn extra potassium from nutrition into a clinical variable. A pharmacist settles it in two minutes. Nobody needs that conversation for a banana; everybody on that list needs it before a potassium tub.
The magnesium half, and the cramp honesty that goes with it
The supplementable half of the pair is the familiar protocol: 300mg elemental magnesium in the evening — Futuro Labs Magnesium Glycinate, 1500mg pure bisglycinate per serving, delayed-release vegan capsules, 22p a night, £19.99 across 90 days — run as a four-to-eight-week diary test, because this site tells the cramp evidence straight: trials in the general population are mixed, the case is strongest where intake genuinely runs low, and the mechanical basics (calf stretching, daytime hydration, a pharmacist medication review) carry the sturdier record. The full honest treatment lives in the night-cramps guide and the cramps rankings; the red flags — walking-triggered calf pain, one hot swollen leg — are repeated there because they matter more than any mineral.
Futuro Labs Magnesium Glycinate
£19.99 for 90-day supply (180 capsules) · ~22p per day
Pros
- 300mg elemental magnesium per serving — 80% NRV
- Bisglycinate (glycinate) form — gentle, well absorbed
- Authorised claims: fatigue reduction, muscle function, psychological function
- 90-day supply £19.99 (~22p/day); 90-cap pouch £9.99
- Delayed-release vegan capsules, UK made
Cons
- Two capsules per serving
- Glycinate costs more per mg than oxide (for good reason)
Available from: Amazon UK — £19.99
Frequently asked questions
Magnesium or potassium for cramps — which do I need?
They're partners, not rivals: both are electrolytes muscle contraction runs on, magnesium holding the electrolyte-balance and muscle-function claims, potassium contributing to normal muscle function too. The practical split is how you top each up — magnesium supplements sensibly (300mg elemental, since diets commonly undershoot), while potassium is a food-first mineral in the UK: rich in ordinary foods and deliberately kept to low doses in OTC supplements because excess potassium is genuinely dangerous.
Why are potassium supplements so low-dose in the UK?
Safety. Blood potassium sits in a narrow band the heart depends on, kidneys do the regulating, and supplemental potassium can overshoot in people with reduced kidney function or on common medications (some blood-pressure drugs especially). UK products therefore cap conservatively, and the sensible route to more potassium is dinner: potatoes, beans, bananas, fish, yoghurt, greens.
Can I take magnesium and potassium together?
Magnesium supplement plus potassium-rich food — yes, and that's the recommended shape. Magnesium supplement plus potassium supplement is rarely necessary and, for anyone with kidney issues or on ACE inhibitors, ARBs, spironolactone or similar, a pharmacist question before anything else. Cramps despite decent intake of both belong in the honest-evidence conversation, and sometimes with a GP.
Sorting the supplementable half?
Futuro Labs Magnesium Glycinate — 300mg elemental evenings. £19.99 for 90 days.
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