Mineral involved in 300+ biochemical reactions
15 of 22 providers
Electrolytes &Minerals
muscle and nerve function
Magnesium is the fourth most abundant mineral in your body and is involved in over 300 enzymatic reactions, including energy production (ATP synthesis), DNA/RNA synthesis, protein synthesis, muscle and nerve function, blood pressure regulation, and glucose control. About 50-60% of your body's magnesium is stored in bones, 25% in muscles, and only 1% circulates in blood. This means serum magnesium (measured in standard blood tests) is a poor marker of total body magnesium status—you can be significantly deficient with "normal"serum magnesium.
Here's the critical insight:magnesium deficiency is epidemic. An estimated 50-75% of Americans don't meet the RDA for magnesium (420 mg/day for men, 320 mg/day for women), and up to 20% have overt deficiency. Modern agricultural practices have depleted soil magnesium, reducing food magnesium content by 30-50% over the past century. Processed foods, stress, alcohol, certain medications (PPIs, diuretics), and chronic diseases all further deplete magnesium. Yet magnesium deficiency is rarely diagnosed because serum magnesium doesn't drop until severe depletion—by the time serum magnesium is low, you're critically deficient.
Red blood cell (RBC) magnesium or ionized magnesium are more sensitive tests of intracellular magnesium status, but they're not routinely available. A better approach:if you have symptoms of magnesium deficiency (muscle cramps, insomnia, anxiety, arrhythmias, constipation) and normal serum magnesium, trial supplementation with 300-400 mg/day magnesium for 2-3 months. Most people benefit, and magnesium toxicity is rare with normal kidney function (excess is excreted).
| Range Type | Level | Significance |
|---|---|---|
| Optimal (Longevity) | 2.2-2.6 mg/dL (serum) | Upper-normal range associated with better cardiovascular and metabolic health. Many functional medicine doctors target >2.2 mg/dL. |
| Adequate (Standard) | 1.8-2.2 mg/dL | Meets standard guidelines but may be suboptimal. Consider supplementation if symptoms (cramps, insomnia, anxiety) despite normal serum level. |
| Low-Normal (Suboptimal) | 1.5-1.8 mg/dL | Low-normal serum magnesium. Likely indicates tissue magnesium depletion. Supplement with 300-400 mg/day elemental magnesium. |
| Deficient | <1.5 mg/dL | Frank magnesium deficiency. Serum magnesium rarely drops this low unless severe depletion or renal wasting. Requires aggressive magnesium replacement (oral or IV). |
<1.2 mg/dL
High (Rare)
Hypermagnesemia. Rare unless severe kidney failure or excessive IV magnesium. Causes muscle weakness, hypotension, bradycardia, respiratory depression.
Magnesium glycinate:300-400 mg elemental magnesium daily. Most bioavailable, gentle on stomach, promotes relaxation and sleep. Preferred form for most people.
Magnesium citrate:300-400 mg daily. Good bioavailability, mild laxative effect (useful for constipation).
Magnesium threonate:2000 mg (144 mg elemental magnesium). Crosses blood-brain barrier, may improve cognitive function and sleep. More expensive.
Magnesium oxide:400-500 mg. Poorly absorbed (~4%), mainly used as laxative. Not recommended for magnesium repletion.
Magnesium malate:300-400 mg. May help with fibromyalgia and chronic fatigue.
Magnesium taurate:300-400 mg. May benefit cardiovascular health (taurine + magnesium synergy).
Topical magnesium (spray, lotion, Epsom salt baths):Absorbed through skin, bypasses GI. Useful adjunct but less reliable than oral.
Dark leafy greens:Spinach, Swiss chard, kale (high in magnesium, 150-200 mg per cooked cup).
Nuts and seeds:Almonds, cashews, pumpkin seeds, sunflower seeds (150-200 mg per ¼ cup).
Legumes:Black beans, chickpeas, lentils (100-120 mg per cup).
Whole grains:Brown rice, quinoa, oats (60-80 mg per cup). Refined grains lose 80-90% of magnesium.
Dark chocolate:70-85% cacao (60-100 mg per oz).
Avocado:1 medium avocado ~60 mg.
Fatty fish:Mackerel, salmon (40-60 mg per 3 oz).
Hard water:Some tap water contains 10-30 mg magnesium per liter (varies by region).
Muscle weakness, fatigue|Nausea, vomiting|Hypotension (low blood pressure)|Bradycardia (slow heart rate)|Flushing, warmth|Loss of deep tendon reflexes|Respiratory depression (if severe)|Cardiac arrest (if very severe, >7 mg/dL)
Source:Hypermagnesemia is rare and occurs only with severe kidney failure, excessive IV magnesium, or massive oral intake (laxative abuse). Normal kidneys excrete excess magnesium.
Kidney failure (end-stage renal disease):Kidneys can't excrete magnesium, causing accumulation.|Excessive IV magnesium:Iatrogenic (medical error) or pre-eclampsia treatment.|Massive oral intake:Laxative abuse (milk of magnesia, Epsom salt ingestion). Requires >5000 mg/day with normal kidney function.|Rare:Hypothyroidism, Addison's disease (reduce renal excretion).
Source:Baseline:Check serum magnesium if symptoms (cramps, insomnia, arrhythmias, anxiety) or risk factors (on PPIs/diuretics, type 2 diabetes, chronic diarrhea).|RBC magnesium:More accurate reflection of intracellular status if available. Normal 4.0-6.5 mg/dL.|After starting supplementation:Retest serum magnesium after 3 months. Goal >2.0 mg/dL. If symptoms resolve, continue maintenance dose (300-400 mg/day).|Annual screening:For patients on chronic PPIs, diuretics, or with type 2 diabetes.|If low serum magnesium (<1.5 mg/dL):Also check potassium and calcium (often co-deficient). Correct magnesium first, as magnesium deficiency impairs potassium repletion.
~50% of Americans consume less than the RDA for magnesium (420 mg men, 320 mg women). Up to 20% have overt deficiency based on dietary surveys. Serum magnesium underestimates true prevalence because it's tightly regulated;tissue depletion occurs first.
Source:Rosanoff A, et al. Suboptimal magnesium status in the US:are the health consequences underestimated? Nutr Rev. 2012;70(3):153-164.
Magnesium deficiency is associated with hypertension, arrhythmias, coronary artery disease, and sudden cardiac death. Meta-analyses show magnesium supplementation (300-400 mg/day) lowers systolic BP by 3-5 mmHg and diastolic BP by 2-3 mmHg. Higher dietary magnesium intake associated with 30% lower CVD risk.
Source:Zhang X, et al. Effects of magnesium supplementation on blood pressure:a meta-analysis. Hypertension. 2016;68(2):324-333.
Low magnesium intake and serum levels strongly associated with insulin resistance and type 2 diabetes (2-3x higher risk). Magnesium is required for insulin receptor function and glucose transport. Magnesium supplementation (300-400 mg/day) improves insulin sensitivity, fasting glucose, and HbA1c in diabetics and prediabetics.
Source:Larsson SC, Wolk A. Magnesium intake and risk of type 2 diabetes:a meta-analysis. J Intern Med. 2007;262(2):208-214.
| Provider | Includes | Annual Cost | Biomarkers |
|---|---|---|---|
 Superpower | ✓ | $199 | 100+ (150 with ratios) |
 WHOOP Advanced Labs | — | $349 | 65 |
 Labcorp OnDemand | — | $398 | 30+ |
| ✓ | $486 | 40+ | |
| ✓ | $468 | 83 | |
| ✓ | $349 | 100+ | |
 InsideTracker | ✓ | $680 | 54 |
 Function Health | ✓ | $365 | 100+ |
| ✓ | $250 | 65 | |
| ✓ | $495 | 70+ | |
| ✓ | $895 | 100+ | |
| ✓ | $1950 | 150+ | |
| — | $399 | 100+ | |
| — | $Varies | 75+ | |
| ✓ | $190 | 100+ | |
| — | $99 | 50 | |
| — | $125 | 60 | |
| — | $199 | 50 | |
| ✓ | $499 | 120+ | |
| — | $4188 | 80+ | |
| ✓ | $375 | 85 | |
| ✓ | $700 | 129 |
15 providers include this biomarker in their panels
This information is for educational purposes only and is not medical advice. Always consult with a qualified healthcare provider about your specific health needs.
