What magnesium actually does in the body
Magnesium is a cofactor in over 300 enzyme reactions: energy production, muscle and nerve signaling, blood pressure, and sleep. What it does, and the dose that does it.
What people ask us next.
- What does magnesium do for the body?
- It is a cofactor in more than 300 enzyme reactions, most tied to ATP (NIH ODS). Practically, that means magnesium is required for energy production, muscle contraction and relaxation, nerve signaling, DNA and protein synthesis, and blood-pressure regulation. The best-supported clinical effects are a small blood-pressure reduction (~2-4 mmHg systolic, Zhang 2016) and a role in glucose metabolism (Larsson & Wolk 2007).
- What is magnesium good for, specifically?
- The strongest evidence is for blood pressure (a modest 2-4 mmHg systolic drop, larger in deficient or hypertensive people) and glucose metabolism. It is also involved in muscle cramps, migraine, and sleep, where the mechanism is clear but the trial data is more mixed. It is not a cure-all; the benefit is largest when you are starting from a deficit, which ~48% of Americans are (NHANES).
- How do I know if I am low in magnesium?
- It is hard to measure. Serum magnesium reflects under 1% of total body stores, so a normal blood test does not rule out a deficit (Workinger et al. 2018). Risk is higher with high alcohol intake, GI malabsorption, type 2 diabetes, or long-term proton pump inhibitor or diuretic use. Early signs are non-specific: cramps, fatigue, poor sleep. The reliable move is to ensure the diet hits the RDA rather than chase symptoms.
- Should I get magnesium from food or a supplement?
- Food first. Magnesium from food arrives with fiber, potassium, and protein and carries no upper limit, because the gut self-limits absorption as intake rises. The densest everyday sources are pumpkin seeds, cooked spinach, black beans, quinoa, and almonds. Supplement only the measured gap, typically 100-200 mg/day, and stay under the 350 mg/day supplemental upper limit.
- Which magnesium form should I take?
- Glycinate and citrate are the best-absorbed, best-tolerated everyday forms; oxide is cheapest but mostly excreted and the most likely to cause diarrhea (Walker et al. 2003). Glycinate is gentle and the default for general use and sleep; citrate is well absorbed and mildly laxative. Our magnesium forms comparison ranks the major forms by $/100mg of elemental magnesium and by use case.
- Does magnesium help you sleep?
- The mechanism is plausible: magnesium dampens the excitatory NMDA receptor and supports GABA and melatonin pathways. The trial evidence is modest and concentrated in older or deficient adults rather than the general population. Glycinate is the form most used for sleep. Our magnesium-for-sleep page covers the form, the dose, and what the trials actually demonstrate.
Every claim, cited.
- [01]NIH Office of Dietary Supplements. Magnesium Fact Sheet for Health Professionals. Cofactor in 300+ reactions; Mg-ATP; RDA and intake gaps.
- [02]Institute of Medicine. 1997. Dietary Reference Intakes for Calcium, Phosphorus, Magnesium, Vitamin D, and Fluoride. National Academies Press. Enzymatic roles and RDA derivation.
- [03]Zhang X, Li Y, Del Gobbo LC, et al. 2016. Effects of magnesium supplementation on blood pressure: a meta-analysis of randomized double-blind placebo-controlled trials. Hypertension 68(2):324-333. ~2 mmHg systolic reduction across 34 RCTs.
- [04]Larsson SC, Wolk A. 2007. Magnesium intake and risk of type 2 diabetes: a meta-analysis. J Intern Med 262(2):208-214. ~15% lower risk per 100 mg/day.
- [05]Moshfegh A, Goldman J, Cleveland L, et al. 2009. What We Eat in America, NHANES. ~48% of the US population consumes less than the EAR for magnesium.
- [06]Workinger JL, Doyle RP, Bortz J. 2018. Challenges in the diagnosis of magnesium status. Nutrients 10(9):1202. Serum magnesium reflects <1% of body stores.
- [07]Walker AF, Marakis G, Christie S, Byng M. 2003. Mg citrate found more bioavailable than other Mg preparations. Magnes Res 16(3):183-191. Organic forms outperform oxide on absorption.
The Larderlab Team builds evidence-led frameworks for eating, lifting, and stocking a kitchen. We cite every claim. We publish the spreadsheet when possible. We buy what we review at retail price. When new data lands, we revise with a dated note.
Next in this hub.
What to Avoid When Taking Collagen: Five Caveats With Evidence Behind Them
Do not count it toward your protein target, do not judge it before 8 to 12 weeks, and if you form kidney stones, know that 30 g of gelatin raised urinary oxalate by 43 percent in a controlled study. The real caveats, and the myths.
8 min · rev 2026-08-24Foods High in Collagen: Why the Real List Is Shorter Than You Think
Collagen exists only in animal connective tissue, so no plant food contains any. Gelatin powder leads at 85.6 g of protein per 100 g, pork skin at 61.3 g. And the most-marketed source, bone broth, tested poorly against supplements.
8 min · rev 2026-08-24Ashwagandha Benefits: What the Trials Show, and the Liver Signal
Pooled across 12 trials in 1,002 people, stress fell with a standardised mean difference of 1.75 and anxiety by 1.55, but heterogeneity was above 83 percent and the certainty of evidence was rated low. The dose that was tested, and the hepatic case series.
8 min · rev 2026-08-24Get the Larderlab Macro Planner.
A Google Sheet that calculates your protein target, splits it across 3-5 meals, and ranks 20 protein sources by $/gram. Free. Copy-and-modify your own version.
By subscribing, you agree to our Privacy Policy. Unsubscribe anytime.