What it does in the body
- Cofactor for 300+ enzymes (ATP-dependent reactions)
- Neuromuscular excitability regulation
- Cardiac rhythm stability
- Blood pressure regulation (vasodilation)
- Insulin sensitivity and glucose metabolism
How much you need (Daily Value)
| Group | Recommended | Source |
|---|---|---|
| Adult male | 400-420 mg | NIH/IOM |
| Adult female | 310-320 mg | NIH/IOM |
| Pregnancy | 350-400 mg | WHO |
| Children | 80 mg (1-3y), 130 mg (4-8y), 240-410 mg (9-18y) | NIH/IOM |
| Older adults | 420 mg (men), 320 mg (women) | NIH/IOM |
Richest food sources
| Food | Amount | Where |
|---|---|---|
| Pumpkin seeds | 550 mg per 100g | Americas |
| Dark chocolate (70-85%) | 228 mg per 100g | global |
| Almonds | 270 mg per 100g | Middle East/California |
| Spinach (cooked) | 87 mg per 100g | global |
| Black beans (cooked) | 70 mg per 100g | Americas |
| Avocado | 29 mg per 100g | Americas |
| Cashews | 292 mg per 100g | South Asia/Africa |
| Quinoa (cooked) | 64 mg per 100g | South America |
In our food database, per 100 g
Highest among our free foods — open the Food Explorer to compare.
If you don't get enough
Mild: Muscle cramps, fatigue, irritability, poor appetite, insomnia
Moderate: Tremor, muscle fasciculations, personality changes, nausea, refractory hypokalemia and hypocalcemia
Severe: Cardiac arrhythmias (torsades de pointes), seizures, coronary artery vasospasm, tetany
Time to onset: Weeks to months for dietary deficiency. Can present acutely with GI losses or renal wasting.
Too much
Upper limit: 350 mg/day from supplements only (no UL for dietary magnesium)
Diarrhea (most common from supplements), nausea, abdominal cramping. Severe hypermagnesemia (usually iatrogenic IV): hypotension, bradycardia, respiratory depression, cardiac arrest
How well you absorb it
30-40% from diet; inversely proportional to intake amount
Helped by: Vitamin D, Protein, Fructose (moderate amounts), Fermentable fibers (gut microbiome)
Hindered by: Phytate, Oxalate, High-dose zinc supplements, Excess calcium, Proton pump inhibitors (chronic use)
Cooking & storage
Magnesium is heat-stable but water-soluble. Boiling vegetables can leach 20-30% of magnesium into cooking water. Steaming and stir-frying preserve more. Refined grain processing removes up to 80% of magnesium.
Nutrisize Health totals every nutrient from what you actually eat, against targets set for your age and sex, and flags what's short — across 4,995 foods, on your device.
