Form Comparison

Magnesium Aspartate vs Magnesium Citrate

How magnesium aspartate and magnesium citrate differ in elemental content, absorption, tolerance, and cost.

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Quick verdict. Both are rated high for absorption, and head-to-head human data do not reliably separate them. Choose magnesium aspartate when it comes in a formula you already want. It offers no distinct advantage over citrate. Choose magnesium citrate when you want proven absorption at the lowest cost and loose stools are not a problem.

Side by Side

Magnesium Aspartate Magnesium Citrate
Elemental content Varies by product 16.2% elemental magnesium
Absorption High High
How it is absorbed Soluble organic salt. Absorption was equivalent to chloride and lactate in Firoz and Graber 2001. Highly soluble organic salt. Produced significantly higher serum and urinary magnesium than oxide in a randomized crossover trial (Kappeler 2017).
Typical dose 100-350 mg elemental magnesium daily 100-350 mg elemental magnesium daily
Common uses general repletion, multi-mineral formulas general repletion, constipation, best value per absorbed mg
Side effects Mild osmotic effect at higher doses. Osmotic laxative effect becomes noticeable above roughly 200 mg elemental per dose.
Cost Moderate Low
Also called magnesium L-aspartate trimagnesium citrate
Labels in index 585 1,343

When to Choose Magnesium Aspartate

Choose magnesium aspartate when it comes in a formula you already want. It offers no distinct advantage over citrate. About 8.4% elemental as the anhydrous salt and lower as the hydrates sold commercially, so the panel figure is the one to use. Common in combination formulas with potassium aspartate.

Magnesium Aspartate

Choose magnesium aspartate when it comes in a formula you already want. It offers no distinct advantage over citrate.

What to look for: Magnesium Aspartate named on the Supplement Facts panel, with the amount per serving stated.

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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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Products on Titrate

In Titrate's index of NIH label data, 585 labels in the Magnesium category list magnesium aspartate and 1,343 list magnesium citrate.

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.