Magnesium
Magnesium is a cofactor in more than 300 enzymatic reactions including ATP production, protein synthesis, and muscle and nerve function. Deficiency is common and can cause fatigue, cramps, arrhythmias, migraines, and insulin resistance. Low levels are seen with poor diet, alcohol use, proton pump inhibitors, diuretics, and gastrointestinal losses; high levels are rare outside kidney failure.
Units: mg/dL; some labs report mmol/L (mmol/L = mg/dL × 0.411). Check the units on your report before comparing to any range here.
Optimal range: who says what
Institutions, researchers and practitioners draw the line in different places. Each position is listed with who holds it and, where a document states it, a link. How we verify ranges.
- Named practitioner2.07-2.5 mg/dLLife Extension · Lab Testing Protocol (Suggested Optimal Ranges)Disclosure: Life Extension sells lab panels that appear in our blood-test comparisons.
- Lab reference interval1.7-2.2 mg/dL (MedlinePlus)What a lab report flags against. A lab interval is not an optimal target.
Practitioner targets are individual positions, often tighter than guideline ranges. Each was checked against its article before publishing.
16 of 21 itemized panels
Electrolytes & Minerals
What is Magnesium?
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.
Magnesium shortfalls are common: almost half (48%) of Americans got less than the required amount of magnesium from food in 2005-2006 (Rosanoff 2012). Processed foods, alcohol, some medications (PPIs, diuretics), and chronic disease can lower magnesium further. Serum magnesium is tightly regulated, so a normal blood level does not rule out low body stores.
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).
Why Magnesium Matters for Longevity
- Energy production: Magnesium is required for ATP synthesis in mitochondria. Every ATP molecule must be bound to magnesium to be biologically active. Deficiency causes fatigue.
- Cardiovascular health: Magnesium relaxes blood vessels, lowers blood pressure, prevents arrhythmias. Deficiency increases risk of hypertension, atrial fibrillation, sudden cardiac death, heart attacks.
- Insulin sensitivity and glucose control: Magnesium is a cofactor for insulin receptors. Deficiency causes insulin resistance, type 2 diabetes. Low magnesium associated with 2-3x higher diabetes risk.
- Bone health: 50-60% of body magnesium is in bones. Magnesium is required for vitamin D activation, calcium regulation, and bone formation. Deficiency increases osteoporosis risk.
- Muscle and nerve function: Magnesium regulates neuromuscular transmission and muscle contraction. Deficiency causes cramps, spasms, tremors, restless legs, migraines.
- Sleep and stress resilience: Magnesium activates GABA receptors, promoting relaxation and sleep. Deficiency causes insomnia, anxiety, stress intolerance.
- Inflammation: Magnesium has anti-inflammatory effects. Deficiency raises CRP and pro-inflammatory cytokines, accelerating aging.
Interpretation bands (curated, PMID-backed)
Holder: OptimizeBiomarkers editorial synthesis of: Magnesium in Prevention and Therapy (Gröber et al., 2015); Effects of Magnesium Supplementation on Blood Pressure: A Meta-Analysis of Randomized Double-Blind Placebo-Controlled Trials (Zhang et al., 2016). No single paper sets these cutoffs; for attributed targets see who says what.
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)
What raises or lowers Magnesium
Causes of high 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).
Causes of low Magnesium
- Low dietary intake: Standard American diet provides only 250-300 mg/day (RDA is 320-420 mg). Processed foods, refined grains depleted of magnesium.
- Soil depletion: Some analyses report lower mineral content in modern crops.
- Malabsorption: Celiac disease, Crohn's disease, chronic diarrhea, gastric bypass, chronic pancreatitis.
- Medications: PPIs (omeprazole), diuretics (furosemide), antibiotics (aminoglycosides), chemotherapy (cisplatin).
- Alcohol abuse: Increases urinary magnesium excretion and impairs absorption.
- Type 2 diabetes: Hyperglycemia causes osmotic diuresis, wasting magnesium in urine.
- Chronic stress: Cortisol and adrenaline increase urinary magnesium loss.
- Aging: Absorption decreases and urinary losses increase with age.
- Chronic kidney disease (moderate): Impaired reabsorption of magnesium.
Symptoms when Magnesium is high or low
When high
- 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)
Hypermagnesemia is rare and occurs only with severe kidney failure, excessive IV magnesium, or massive oral intake (laxative abuse). Normal kidneys excrete excess magnesium.
When low
- Muscle cramps, spasms, twitches (especially calves, feet at night)
- Restless leg syndrome
- Insomnia, difficulty falling or staying asleep
- Anxiety, nervousness, irritability
- Fatigue, low energy
- Constipation (magnesium relaxes intestinal smooth muscle)
- Migraine headaches (magnesium deficiency lowers threshold)
- High blood pressure, hypertension
- Arrhythmias: Premature beats, atrial fibrillation, palpitations
- Tremors, muscle weakness
- Numbness, tingling (paresthesias)
- Depression, mood changes
- Osteoporosis (magnesium required for bone formation and vitamin D activation)
- Increased inflammation (elevated CRP)
Tissue deficiency can exist with "normal" serum magnesium levels. RBC magnesium is more sensitive.
How to move Magnesium
Effect sizes (how much something moves the marker) appear only where the paper cited under the item states them. Talk to your clinician before starting or changing any medication or supplement.
Magnesium Supplementation (Dose and Form)
- 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.
Dietary Sources of Magnesium
- 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). Refining grains removes most of their 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).
Optimize Magnesium Absorption and Retention
- Vitamin D: Magnesium is required for vitamin D activation (25(OH)D → 1,25(OH)2D). Vitamin D supplementation without magnesium can worsen deficiency.
- Vitamin B6: Enhances magnesium uptake into cells.
- Avoid magnesium inhibitors: Alcohol, caffeine (>3 cups coffee/day), high-dose zinc (>50 mg), high-calcium diets (>2000 mg/day) compete with or deplete magnesium.
- Adequate protein: Magnesium absorption requires adequate protein intake.
- Probiotics and gut health: Healthy gut microbiome enhances magnesium absorption. Dysbiosis impairs absorption.
Address Medications That Deplete Magnesium
- PPIs (omeprazole, pantoprazole): Long-term use (>1 year) impairs magnesium absorption. Check magnesium annually, supplement if needed.
- Diuretics: Loop diuretics (furosemide) and thiazides cause urinary magnesium wasting. Supplement with 300-400 mg/day.
- Bisphosphonates (alendronate, risedronate): Used for osteoporosis, can lower magnesium.
- Antibiotics: Aminoglycosides, fluoroquinolones increase urinary magnesium loss.
- Chemotherapy: Cisplatin, carboplatin cause severe magnesium wasting.
Treat Underlying Causes
- Chronic diarrhea, malabsorption: Celiac disease, Crohn's disease, chronic pancreatitis impair magnesium absorption. May require higher oral doses (600-800 mg/day) or IV magnesium.
- Type 2 diabetes: Hyperglycemia causes urinary magnesium wasting (osmotic diuresis). Magnesium supplementation improves insulin sensitivity and glycemic control.
- Alcohol abuse: Depletes magnesium via increased urinary excretion and malabsorption.
- Chronic stress: Elevates cortisol and adrenaline, which increase urinary magnesium loss.
When to retest
- 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. Life Extension suggests 2.07-2.5 mg/dL (see who says what above). 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.
Scientific Evidence
Magnesium Intake in the US
Almost half (48%) of the US population consumed less than the required amount of magnesium from food in 2005-2006. Low magnesium intake and blood levels have been associated with type 2 diabetes, metabolic syndrome, hypertension, and atherosclerotic disease. The authors argue intake requirements may be underestimated if balance-study subjects had unrecognized chronic deficiency.
Source: Suboptimal magnesium status in the United States: are the health consequences underestimated?
Magnesium Supplementation and Blood Pressure
A meta-analysis of 34 placebo-controlled trials (2,028 adults) found magnesium at a median 368 mg/day for 3 months lowered systolic blood pressure by 2.0 mmHg and diastolic by 1.8 mmHg.
Magnesium Intake and Type 2 Diabetes
A meta-analysis of 7 prospective cohorts (286,668 participants) found each 100 mg/day higher magnesium intake associated with 15% lower risk of type 2 diabetes (relative risk 0.85).
Source: Magnesium intake and risk of type 2 diabetes: a meta-analysis.
Which Providers Test Magnesium?
Cheapest: Empirical Health at $190/year. Most comprehensive: Function Health, 160+ biomarkers for $365/year.
16 panels that include it, cheapest first
| Provider | Annual Cost | Total Biomarkers | $/Biomarker |
|---|---|---|---|
| $190 | 100+ | $1.90 | |
| $250 | 65 | $3.85 | |
| $297 | 100+ | $2.97 | |
 Superpower | $349 | 100+ | $3.49 |
| $349 | 75+ | $4.65 | |
 Function Health | $365 | 160+ | $2.28 |
| $365 | 100+ | $3.65 | |
| $375 | 108 | $3.47 | |
| $449 | 83 | $5.41 | |
| $495 | 80+ | $6.19 | |
| $499 | 100+ | $4.99 | |
| $700 | 138 | $5.07 | |
| $829 | 54 | $15.35 | |
| $895 | 100+ | $8.95 | |
| $1198 | 40+ | $29.95 | |
| $1950 | 130+ | $15.00 |
$/Biomarker is annual cost divided by the panel's advertised biomarker count, not the price of this one test. We track 23 blood test providers (32 plans); 21 of those plans are itemized marker by marker. Compare all of them.
5 itemized panels do not include Magnesium
WHOOP Advanced Labs · Labcorp OnDemand · Oura Health Panels · SiPhox Health · Healthspan
11 providers not itemized in our matrix
We have not itemized these marker by marker (some sell tests one at a time), so this page cannot say whether they offer Magnesium. Check with them directly.
Life Extension Standard · Quest Health · Ultrahuman Blood Vision · Lifeforce · Hundred Health · Personalabs · Walk-In Lab · HealthLabs · WHOOP Specialized Panels · Marek Health Essential · Vitality Blueprint Upload
Frequently Asked Questions
What is the optimal range for Magnesium?
Named practitioners target: 2.07-2.5 mg/dL (Life Extension). Lab reference interval: 1.7-2.2 mg/dL (MedlinePlus). That is what a lab report flags against, not an optimal target.
Which blood test providers include Magnesium?
16 of the 21 blood testing panels we itemize marker by marker include Magnesium in their panels. This biomarker is widely available across major providers.
Related: YouBoost rates lifestyle and supplement interventions by evidence.
Medical Disclaimer
This information is for educational purposes only and is not medical advice. Always consult with a qualified healthcare provider about your specific health needs.
Last reviewed Sep 23, 2026 · First published Sep 30, 2025