What is Magnesium?
Magnesium is the fourth most abundant mineral in the human body and is involved in over 300 enzymatic reactions. It plays a role in protein synthesis, muscle and nerve function, blood glucose control, blood pressure regulation, and energy production.
Despite its importance, an estimated 68–79% of adults in Western countries don't meet the recommended daily intake. Athletes have even higher requirements due to increased losses through sweat and urine during exercise.
Why athletes need more
- Exercise increases urinary and sweat losses by up to 50%
- High-carbohydrate diets increase magnesium requirements
- Stress (physical and psychological) depletes magnesium rapidly
- Many high-protein foods are low in magnesium
How It Works
Magnesium acts as a cofactor for hundreds of enzymes. For athletes, four mechanisms are most relevant:
Magnesium and testosterone
A 2011 study in Biological Trace Element Research found that magnesium supplementation (10mg/kg/day) significantly increased free and total testosterone levels in both sedentary and exercising men. Exercising men saw larger gains — consistent with the idea that athletes are most depleted and therefore have the most to gain.
Dosage, Timing & Forms
Which form is best?
The form of magnesium matters — absorption and side effects vary significantly:
- Magnesium glycinate — best absorbed, gentlest on digestion, ideal for sleep and daily use. Our top recommendation.
- Magnesium malate — good absorption, may improve energy and reduce muscle pain. Good daytime option.
- Magnesium citrate — highly bioavailable and affordable. Can have a mild laxative effect at higher doses.
- Magnesium oxide — cheapest form, but only ~4% absorption. Mostly useful as a laxative. Avoid for supplementation goals.
- Magnesium threonate — crosses the blood-brain barrier effectively. Promising for cognitive benefits but expensive and requires higher doses.
Best Magnesium Supplements
We prioritise: elemental magnesium content per serving, bioavailable form, no unnecessary additives, and third-party testing.
Frequently Asked Questions
Can I get enough magnesium from food?
Theoretically yes — dark leafy greens, nuts, seeds, legumes, and dark chocolate are rich sources. In practice, modern agricultural soils are depleted in magnesium, food processing removes much of it, and athletes have elevated requirements. Most people who eat a typical Western diet and train regularly benefit from supplementation.
Will magnesium help me sleep better?
Strong evidence suggests yes, particularly if you're deficient. A 2012 double-blind trial found 500mg magnesium improved sleep onset, sleep time, sleep efficiency, and early morning awakening in elderly subjects with insomnia. Athletes with high training loads often report significant sleep quality improvements within 1–2 weeks of supplementation.
Does magnesium stop muscle cramps?
Magnesium deficiency is a well-established cause of muscle cramps. If your cramps are caused by low magnesium, supplementation can be dramatically effective within days. However, cramps also occur from dehydration and electrolyte imbalances (low sodium, potassium), so magnesium may not fix cramps with other root causes.
Can too much magnesium be harmful?
From food, magnesium toxicity is essentially impossible. From supplements, doses over 350–400mg elemental can cause loose stools or diarrhoea in some people. Very high doses (several grams) can cause hypotension and, rarely, more serious issues. Standard supplemental doses of 200–400mg per day are safe for healthy adults.
Should I take it with or without food?
Either works, but taking magnesium with food reduces the chance of stomach upset, particularly with more absorbable forms like glycinate or malate. Oxide and citrate forms are more likely to cause GI effects and are better tolerated with food.