Magnesium

Your intake

What each level of magnesium does

Approximate dose-response bands. Individual response varies — these are starting points, not prescriptions.

1. Severely lowYOU ARE HERE

   0 mg – 139 mg

   Cramps, restless sleep, anxiety, glucose dysregulation. ~50% of US adults are below the EAR.

2. Insufficient

   139 mg – 420 mg

   Most diets fall short; the average US intake is ~270 mg vs the 420 mg DV.

3. Adequate

   420 mg – 630 mg

   Daily target met. Supports 300+ enzymatic reactions, muscle relaxation, glucose handling.

4. Over upper limit

   350 mg – +

   Supplemental UL is 350 mg (separate from total diet). Stop or split doses smaller across the day.

Overview

Cofactor in more than 300 enzyme systems, including every ATP-using reaction (ATP must be bound to Mg2+ to be biologically active). Roughly half of US adults fail to meet RDA. Subclinical insufficiency is the modern norm because grain refining strips magnesium, and water softening removes it from drinking water.

Functions

• ●Required for ATP synthesis and hydrolysis (energy metabolism)
• ●Regulates muscle and nerve excitability (calcium antagonist at NMDA receptor)
• ●Cofactor in protein and DNA synthesis
• ●Cofactor in vitamin D activation (both hepatic and renal hydroxylation)
• ●Maintains potassium homeostasis (Na/K ATPase)

Mechanism

Acts as a natural calcium channel blocker: magnesium occupies the NMDA receptor pore at rest, blunts L-type calcium channel activity, and stabilises cardiac and smooth muscle. Low Mg unmasks excess calcium signalling — explaining cramps, arrhythmias, vasoconstriction, and migraine susceptibility seen in deficiency.

Benefits

• ●Reduces migraine frequency (400 mg/day, ~3 month onset)
• ●Improves sleep quality in deficient adults
• ●Lowers blood pressure modestly (especially with low baseline intake)
• ●Reduces nocturnal leg cramps in pregnancy
• ●Improves insulin sensitivity in deficient adults
• ●Threonate form improves working memory in small cognitive trials

Deficiency

Frank hypomagnesemia is uncommon in healthy adults but subclinical insufficiency is widespread — RBC magnesium is a more sensitive marker than serum. Conventional serum tests miss it.

Excess

UL of 350 mg/day applies only to supplemental magnesium (food magnesium has no UL). Excess from supplements causes osmotic diarrhea long before reaching toxicity. True hypermagnesemia is essentially limited to renal failure.

Forms

• Magnesium glycinate (bisglycinate)
  Well-absorbed, gentle, calm-focused; best general-purpose
• Magnesium citrate
  Well-absorbed; mild laxative effect; common form
• Magnesium malate
  Energy-supporting in CFS protocols; well-absorbed
• Magnesium L-threonate (Magtein)
  Crosses BBB; cognitive niche
• Magnesium chloride / lactate
  Well-absorbed, neutral profile
• Magnesium oxide
  Cheapest; <5% bioavailable; laxative; poor general choice
• Magnesium sulfate (Epsom salt)
  Topical / laxative use; minimal oral absorption

Food sources

• Pumpkin seeds (raw) · 1 oz150 mg
• Almonds · 1 oz80 mg
• Cooked spinach · 1 cup160 mg
• Black beans (cooked) · 1/2 cup60 mg
• Dark chocolate (70%+) · 1 oz65 mg
• Avocado · 1 medium60 mg

Supplement forms

Glycinate, malate, citrate, and threonate are the well-absorbed forms. Avoid magnesium oxide and sulfate as the primary source — under 5% bioavailable, mostly laxative. Threonate has the strongest evidence for crossing the blood-brain barrier and is the niche pick for cognition; glycinate is the best general-purpose default.

Bioavailability

Absorption ranges from <5% (oxide) to 30–40% (glycinate, citrate). Splits dose-dependently — 200 mg twice daily absorbs better than 400 mg once. High-dose calcium, zinc, and phytate reduce uptake. Active transport saturates; passive paracellular absorption takes over at higher doses.

Longevity relevance

Strong observational signal: higher dietary magnesium associates with lower all-cause mortality, cardiovascular events, and type 2 diabetes incidence. Adequacy supports insulin signalling, blood pressure regulation, and bone density — three of the biggest healthspan levers.

Relationships

References

• NIH ODS — Magnesiumguideline
• Linus Pauling Institute — Magnesiumreview
• Zhang — magnesium intake and all-cause mortality meta-analysis (BMC Med 2016)review
• Peikert — magnesium for migraine (Cephalalgia 1996)study

About Magnesium

Cofactor for 300+ enzymes; sleep, muscle relaxation, ATP.

Role

300+ enzymes

Daily target

420 mg (DV)

Upper limit

350 mg

Also called

magnesium, magnesium glycinate, magnesium citrate, magnesium malate, magnesium oxide, magnesium threonate

UL note: Applies to supplemental magnesium only (NIH ODS) — food magnesium is unrestricted, which is why the UL sits below the 420 mg DV.

Forms with lower absorption: oxide, sulfate. Prefer better-absorbed forms when supplementing.