7 best magnesium sources for athletes
The RDA for magnesium is 400-420mg for men and 310-320mg for women over 19. Most athletes fall short of it. A meta-analysis of 31 studies found the majority of athletes consuming less than the recommended amount, despite training demands that arguably push requirements higher, not lower (PMC review, 2025).
That matters for more than the muscle-cramp myth you've probably heard. Higher serum magnesium is linked to better grip strength, lower-leg power, knee extension torque and jumping performance in cross-sectional studies. Here are the seven sources worth knowing, ranked by how much magnesium they actually deliver.
1. Pumpkin seeds
One of the densest food sources available. Roughly 150mg per 30g serving, around a third of the daily target in a small handful. Easy to add to porridge or eat as a snack between sessions.
2. Dark leafy greens
Spinach and chard deliver around 78-80mg per cooked cup. Cooking reduces the oxalate content that otherwise blocks some mineral absorption, so cooked beats raw here if you're eating it specifically for the magnesium.
3. Dark chocolate (70%+ cacao)
Around 65mg per 30g square of high-cocoa dark chocolate. Genuinely one of the few "treat" foods where reaching for more actually serves a training goal, though don't use this as licence to eat a full bar.
4. Almonds and cashews
Roughly 80mg per 30g (a small handful) for almonds, slightly less for cashews. Convenient, portable, no prep needed, which makes them realistic to actually eat consistently rather than aspirational.
5. Black beans and legumes
Around 120mg per cooked cup. Also brings fibre and plant protein, useful if you're already tracking those alongside magnesium as part of a broader recovery-focused diet.
6. Magnesium glycinate or citrate supplements
If food intake alone isn't closing the gap, supplemental forms matter. Glycinate is generally better tolerated on the gut than magnesium oxide, and citrate has reasonable bioavailability too. Oxide is cheap but poorly absorbed, so check the label rather than assuming all magnesium supplements are equal. [SOURCE NEEDED] for exact bioavailability percentages, these vary across studies and individuals.
7. Magnesium-rich electrolyte formulas
This is where the cramp research gets interesting. One study on half-marathon runners found magnesium-rich electrolyte hydration reduced exercise-associated muscle cramps: roughly 46% of athletes using water alone experienced cramps, versus 21% using a magnesium-rich electrolyte mix (Journal of Exercise and Nutrition).
Worth being straight about the bigger picture though: the broader evidence on magnesium specifically preventing cramps is mixed, and several reviews describe the magnesium-cramp link as limited or inconsistent (PMC, "Can Magnesium Enhance Exercise Performance?"). Hydration and sodium intake likely matter more for most cramping than magnesium alone, a point we go into further in 7 electrolyte mistakes endurance athletes make. Treat magnesium as one part of a hydration strategy, not a guaranteed fix.
Why athletes specifically fall short
Sweat carries magnesium out along with sodium, potassium and calcium, so training volume itself increases the amount you need to replace, not just what a sedentary RDA accounts for. Add in that a lot of athletes eat for calories and protein first and vegetables last, and the gap is easy to explain: high output, inconsistent intake.
Restrictive dieting phases make this worse. If you've cut calories to manage weight for a race, magnesium-dense foods (nuts, seeds, legumes) are often the first things trimmed because they're calorie-dense. Worth checking your intake specifically during a cut, not just during normal training blocks.
How much is too much
Food sources of magnesium don't pose a realistic risk of overdoing it, the kidneys clear excess through urine. Supplemental forms can, in high doses, cause loose stools or GI discomfort, which is your body's way of telling you to back off the dose rather than a sign of a serious problem. The tolerable upper limit for supplemental magnesium (separate from food-sourced magnesium) is 350mg/day for adults, per the NIH Office of Dietary Supplements. Stay under that from supplements alone and get the rest from food.
The realistic approach
Food first. Pumpkin seeds, leafy greens and legumes get most athletes close to the RDA without supplementing anything. If training volume is high and diet is inconsistent, a glycinate or citrate supplement fills the gap without the gut issues that come from cheaper forms.
What this means for your training. Magnesium won't fix a fuelling or hydration problem on its own, but chronic under-intake is common enough among athletes that it's worth auditing your actual diet against the RDA rather than assuming you're covered.
A simple way to check: track a normal training day's food against the food sources above. Most people who do this once are surprised by how far short they land. It's rarely about eating badly. Diets built around protein and carbs for training fuel just tend to leave magnesium-dense foods out entirely. Fix that with two or three of the sources above eaten consistently, and a supplement only becomes necessary if the gap is still there after the food side is genuinely covered.
FAQ
What's the best form of magnesium for athletes? Glycinate and citrate are generally better absorbed and better tolerated than oxide. Check the label on any supplement rather than assuming all forms are equal.
Does magnesium actually stop muscle cramps? The evidence is mixed. Some studies on magnesium-rich electrolyte formulas show reduced cramp incidence, but broader reviews describe the link as inconsistent. Hydration and sodium likely play a bigger role for most athletes.
How much magnesium do athletes need per day? The RDA is 400-420mg for men and 310-320mg for women over 19. Active individuals may need more due to sweat losses and training demand, though there's no separate official RDA specifically for athletes.