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Muscle cramps
Night cramps and exercise cramps are extremely common, and the nutritional explanations attached to them are among the least well supported on this whole page.
General information only, not a diagnosis. A symptom is not proof of a deficiency — most symptoms here have many possible causes, and the common ones are rarely nutritional. Do not start a supplement to treat a symptom; the safe route is a blood test if one is warranted, and a doctor to interpret it. Use the red-flag list on each page, and see a clinician for anything that persists or worries you.
The folk model is straightforward: cramps are caused by a mineral deficiency, usually magnesium, occasionally potassium or calcium, and the fix is a supplement. It is a satisfying story and the trial evidence has been unkind to it. Systematic reviews of magnesium for muscle cramps have generally not found a clinically meaningful reduction in older adults, which is the group in which night cramps are commonest and in which the studies were done.
The electrolyte-and-dehydration story for exercise cramps has fared a little better but not much. Cramps during prolonged exercise do cluster in hot conditions and in heavy sweaters, which is suggestive; but they also occur in well-hydrated athletes, they are often localised to the muscles being worked hardest rather than generalised, and the competing explanation — neuromuscular fatigue producing altered reflex control — accounts for those observations better. In practice both mechanisms probably contribute in different people.
What does show up consistently is context. Night cramps become commoner with age, in pregnancy, with certain medicines — diuretics are the classic example — and in people with peripheral arterial disease or nerve compression. Exercise cramps cluster around unaccustomed intensity, new movements and end-of-race fatigue. None of that is a deficiency, and all of it is more actionable.
The measures with the best practical record are dull: stretch the muscle during the cramp, keep general conditioning and stretching going for the muscles that cramp, do not increase training load abruptly, and if you sweat heavily in the heat, replace sodium as well as water. If cramps are frequent, severe, one-sided, or accompanied by weakness or numbness, that is a medical question rather than a mineral one.
Nutrients commonly discussed for muscle cramps
Each nutrient below is rated for how strong the evidence is that it relates to this symptom. "Relevant only if you are deficient" means it can matter when your level is genuinely low, but topping it up when it is not low does nothing.
Magnesium Weak evidence
The most commonly recommended and the least supported. Reviews of trials in older adults with night cramps have generally not shown a meaningful benefit. Frank magnesium deficiency does cause neuromuscular symptoms, but it is uncommon in people eating a mixed diet.
| Everyday food | Magnesium per 100 g |
|---|---|
| Rice bran | 781 mg |
| Hulled hemp seed | 700 mg |
| Canadian cultivated emi-tsunomata seaweed, dry | 692 mg |
| Wheat bran | 611 mg |
| Kretschmer toasted wheat bran | 606 mg |
| Pumpkin seeds | 592 mg |
Full ranking: foods highest in magnesium.
Potassium Relevant only if you are deficient
Low blood potassium causes muscle symptoms, but it is a laboratory finding with specific causes — certain diuretics, prolonged vomiting or diarrhoea — rather than something a normal diet produces. Potassium supplements can be dangerous in people with kidney disease, so this is emphatically not a self-prescription.
| Everyday food | Potassium per 100 g |
|---|---|
| Reduced sodium soy sauce | 3098 mg |
| Canadian cultivated emi-tsunomata seaweed, dry | 2944 mg |
| Soy flour, raw | 2515 mg |
| Soy flour, defatted | 2384 mg |
| Yeast extract spread | 2100 mg |
| Soy flour, low-fat | 2090 mg |
Full ranking: foods highest in potassium.
Calcium Relevant only if you are deficient
Low blood calcium causes cramping and tetany, and it too is a laboratory finding with specific causes rather than a dietary shortfall. Dietary calcium matters for bone, not for the average night cramp.
| Everyday food | Calcium per 100 g |
|---|---|
| American pasteurized process cheese product | 1375 mg |
| Dry nonfat milk | 1257 mg |
| Shredded Parmesan cheese | 1253 mg |
| Hard Parmesan cheese | 1184 mg |
| Cocoavia chocolate bar | 1164 mg |
| Reduced-fat Mexican blend cheese | 1146 mg |
Full ranking: foods highest in calcium.
Sodium Mixed evidence
The one electrolyte with a plausible role in exercise cramps, in people losing large amounts of sweat over long sessions in the heat. There is no per-food sodium ranking on this page because salt content is dominated by processing rather than by the food itself.
Source: Foods richest in each nutrient: USDA FoodData Central SR Legacy (public domain), per 100 g · checked 2026-09-02
Causes that are usually more likely
Before a nutrient, these are the explanations a clinician would normally consider first for muscle cramps:
- Age — night cramps become steadily more common
- Pregnancy, particularly later on
- Medicines, especially diuretics
- Unaccustomed or unusually intense exercise
- Prolonged standing or an awkward sustained position
- Peripheral arterial disease, or nerve root compression
- Thyroid and kidney conditions
- Heavy sweating over long sessions in heat
When to see a doctor
Treat these as reasons to seek a professional opinion rather than to self-treat:
- Cramp with weakness, numbness or tingling that persists afterwards
- Calf pain that comes on reliably when walking and stops when you rest
- One-sided leg pain with swelling, warmth or redness
- Cramps that started after a new medicine
- Very frequent or very severe cramps disrupting sleep every night
- Dark urine after exercise, especially with severe muscle pain
This list is not exhaustive, and a symptom that is severe, persistent or getting worse always deserves a professional opinion. If you feel very unwell, seek urgent care rather than reading further.
Frequently asked questions
Does magnesium stop night cramps?
The trial evidence in older adults has generally not shown a clinically meaningful benefit. It is widely recommended anyway, which is a good example of a folk remedy outliving its evidence.
Should I drink an electrolyte drink for cramps?
For long, hot, sweaty sessions, replacing sodium alongside water is reasonable. For a night cramp in bed, there is no mechanism for it to help.
Does this symptom mean I have a deficiency?
No. Muscle cramps has many possible causes and most are not nutritional. A nutrient link is worth checking with a blood test only when other clues point that way — it is never established by the symptom alone.
Other symptoms
Tiredness and low energy
Tiredness is the most searched symptom on this list and the least specific. It is a normal response to poor sleep, stress and overwork, a feature of dozens of medical conditions, and occasionally the presenting sign of a nutrient deficiency that a blood test would find in minutes.
Hair loss and thinning
Hair shedding has a long list of causes, most of which are not nutritional. The commonest by a wide margin is genetic pattern hair loss, followed by telogen effluvium — a delayed shedding response to a stressor two or three months earlier.
Brittle, splitting or ridged nails
Nails split, peel and ridge for reasons that are mostly mechanical and environmental. Nutrition is in the conversation, but it is well down the list behind water, detergent, solvents and age.
Low mood
Low mood is a symptom, not a diagnosis, and the distance between a low week and a depressive illness is a clinical judgement rather than something a checklist can make. This page covers only the nutritional part of a much larger conversation.
Poor concentration and brain fog
"Brain fog" is a description rather than a diagnosis, and it covers everything from a bad night's sleep to the aftermath of an infection to an untreated attention disorder.
Getting ill often
Catching several colds a winter is normal, particularly for adults living with young children. The nutrients associated with immune function are worth knowing about, and the marketing around them is far ahead of the evidence.
All symptoms · Nutrient toplists · Blood test reference ranges
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