Form Comparison

Magnesium Citrate vs Magnesium L-Threonate

How magnesium citrate and magnesium L-threonate differ in elemental content, absorption, tolerance, and cost.

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Quick verdict. Absorption evidence is stronger for magnesium citrate (rated high) than for magnesium L-threonate (rated moderate), though the gap reflects thinner data more than demonstrated poor absorption. Choose magnesium citrate when you want proven absorption at the lowest cost and loose stools are not a problem. Choose magnesium L-threonate when you specifically want the form studied for cognition and accept thin evidence and high cost.

Side by Side

Magnesium Citrate Magnesium L-Threonate
Elemental content 16.2% elemental magnesium 8.3% elemental magnesium
Absorption High Moderate
How it is absorbed Highly soluble organic salt. Produced significantly higher serum and urinary magnesium than oxide in a randomized crossover trial (Kappeler 2017). Threonate is a vitamin C metabolite. In rodents it raised cerebrospinal fluid magnesium more than other salts; human brain uptake has not been directly measured.
Typical dose 100-350 mg elemental magnesium daily 1.5-2 g compound daily (about 104-144 mg elemental)
Common uses general repletion, constipation, best value per absorbed mg cognition (limited evidence)
Side effects Osmotic laxative effect becomes noticeable above roughly 200 mg elemental per dose. Gentle at the low elemental doses involved.
Cost Low High
Also called trimagnesium citrate Magtein, magnesium threonate
Labels in index 1,343 95

When to Choose Magnesium Citrate

Choose magnesium citrate when you want proven absorption at the lowest cost and loose stools are not a problem. Hydrated or partially neutralized citrate powders can run 11-14% elemental rather than 16.2%. Citrate also alkalinizes urine, which is why it appears in kidney stone prevention.

Magnesium Citrate

The value choice for repletion. Proven absorption advantage over oxide at a low cost per absorbed milligram.

What to look for: Capsules or tablets stating elemental mg per serving. Expect looser stools above about 200 mg per dose.

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When to Choose Magnesium L-Threonate

Choose magnesium L-threonate when you specifically want the form studied for cognition and accept thin evidence and high cost. Human cognitive evidence is one small industry-funded RCT (Liu 2016). It delivers little elemental magnesium per dollar, so it is a poor choice for correcting a deficit.

Magnesium L-Threonate

The only form studied for cognition, on thin and industry-funded evidence. Poor value for correcting a deficit.

What to look for: Magtein (the patented form) with about 144 mg elemental magnesium per 2 g daily serving.

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Products on Titrate

In Titrate's index of NIH label data, 1,343 labels in the Magnesium category list magnesium citrate and 95 list magnesium L-threonate.

Open supplement search

Supplement Search loads one category at a time. Choose the Magnesium tab, then type a form such as "bisglycinate" under Must contain, or a form to avoid under Must not contain.

Related

References

NIH Office of Dietary Supplements. Magnesium: Fact Sheet for Health Professionals.

Firoz M, Graber M. Bioavailability of US commercial magnesium preparations. Magnes Res. 2001;14(4):257-262.

Kappeler D, et al. Higher bioavailability of magnesium citrate as compared to magnesium oxide shown by evaluation of urinary excretion and serum levels after single-dose administration in a randomized cross-over study. BMC Nutr. 2017;3:7.

Pardo MR, et al. Bioavailability of magnesium food supplements: A systematic review. Nutrition. 2021;89:111294.

Zhang X, et al. Effects of Magnesium Supplementation on Blood Pressure: A Meta-Analysis of Randomized Double-Blind Placebo-Controlled Trials. Hypertension. 2016;68(2):324-333.

Holland S, et al. Evidence-based guideline update: NSAIDs and other complementary treatments for episodic migraine prevention in adults. Neurology. 2012;78(17):1346-1353.

Garrison SR, et al. Magnesium for skeletal muscle cramps. Cochrane Database Syst Rev. 2020;9(9):CD009402.

Liu G, et al. Efficacy and Safety of MMFS-01, a Synapse Density Enhancer, for Treating Cognitive Impairment in Older Adults: A Randomized, Double-Blind, Placebo-Controlled Trial. J Alzheimers Dis. 2016;49(4):971-990.