mineral · for muscle cramps
Magnesium Glycinate
Magnesium is what lets a muscle let go after contracting, which is the obvious theory for cramp.
Say that in clinical terms
Magnesium is essential for muscle relaxation, acting as a natural calcium channel blocker. It regulates the neuromuscular junction by modulating acetylcholine release and supporting the calcium-magnesium ATPase pump that returns muscles to resting state.
How strong is the research?
A Cochrane review of 7 trials in 406 people: unlikely to meaningfully reduce cramp.
1 paper read, 1 against.
Who was studied: Older adults averaging 61 to 69, and pregnant women. Exercise cramp was not tested.
How much to take
daily (evening preferred)
300–400 mg
Magnesium deficiency is the most common nutritional cause of muscle cramps. Glycinate form is well-absorbed and gentle.
Before you take it
- NIH ODS Tolerable Upper Intake Level (UL) for supplemental magnesium is 350 mg/day for adults; the principal adverse effect above the UL is osmotic diarrhea; hypermagnesemia is rare with intact renal function but possible with chronically elevated doses.
- Tetracycline antibiotics (e.g., doxycycline, demeclocycline) and quinolone antibiotics (e.g., ciprofloxacin, levofloxacin): take the antibiotic at least 2 hours BEFORE or 4-6 hours AFTER magnesium supplementation, per NIH ODS. Note: this timing requirement is asymmetric.
- Bisphosphonates (e.g., alendronate): magnesium reduces oral bisphosphonate absorption; take at least 2 hours apart, per NIH ODS.
- Antihypertensive medications (ACE inhibitors, ARBs, calcium channel blockers): magnesium may potentiate blood-pressure-lowering effects; blood pressure should be monitored when these are combined.
- Loop diuretics (furosemide) and thiazide diuretics increase renal magnesium excretion; potassium-sparing diuretics decrease magnesium excretion — both are clinically relevant interactions in common patient populations.
- Long-term proton pump inhibitor (PPI) use reduces intestinal magnesium absorption and causes hypomagnesemia independent of dietary intake.
- Renal insufficiency and chronic kidney disease: impaired renal magnesium excretion substantially increases hypermagnesemia risk; supplementation requires medical supervision.
- The antacid effect seen with magnesium hydroxide, carbonate, and oxide forms is form-specific and does not apply to magnesium glycinate at typical supplement doses.
- Gastrointestinal adverse effects (diarrhea, abdominal cramping) were reported in 11-37% of trial participants taking magnesium in cramp trials — clinically relevant because this is the primary dose-limiting adverse effect and the event rate was specifically measured and reported in the cited Cochrane review
When to take it
Best taken: evening
What we make of it
Cochrane concluded with moderate certainty that it is unlikely to help.
The detail
The source is a Cochrane review rather than a single trial. Its 2020 update, pooling 5 trials in 271 older adults, concluded with moderate certainty that magnesium is unlikely to reduce how often or how badly people cramp.