Magnesium glycinate vs citrate: which one to actually buy

If the question were "which form has the highest absolute bioavailability", the answer would be a wash — both glycinate and citrate land in the 30-40% range, with citrate slightly higher in head-to-head studies. But absorption isn't the only thing that matters when you're picking a daily supplement, and once you factor in dose tolerance and downstream effects, the two forms have meaningfully different use cases.

Glycinate: when calm matters

Magnesium glycinate (also sold as bisglycinate) is magnesium bonded to two glycine molecules. The carrier amino acid is the secret sauce here — glycine is itself a mildly inhibitory neurotransmitter, with documented effects on sleep onset and subjective calm at supraphysiologic doses.

What that translates to in practice:

• Sleep support — taken 30-60 minutes before bed, 200-400 mg elemental magnesium glycinate has the strongest evidence base for shortening sleep latency among the magnesium forms.
• Anxiety profile — controlled trials in mild generalized anxiety show modest benefit from magnesium glycinate that doesn't replicate as cleanly with the inorganic forms.
• Gentle on the gut — even at 400-600 mg elemental, glycinate rarely causes loose stools. You can take a daily-sufficient dose in one sitting without GI compromise.

Cost: $0.10-0.20 per dose at the cheap end of the US market.

Citrate: when budget matters

Magnesium citrate is magnesium bonded to citric acid. Bioavailability is comparable to glycinate, but the citrate counter-ion is mildly osmotic — it draws water into the gut. Therapeutic uses include constipation relief at 300+ mg, but for most users this is an annoying side effect, not a feature.

When citrate is the right pick:

• Daily supplementation under 200 mg elemental — well below the GI tolerance threshold, much cheaper per gram than glycinate.
• You also have mild constipation — the laxative effect becomes a co-benefit instead of a downside.
• Your local pharmacy doesn't stock glycinate — citrate is the second-best option on absorption, and it's stocked everywhere.

Cost: $0.05-0.12 per dose. Often half the price of an equivalent glycinate dose.

The decision tree

1. You take it for sleep, anxiety, or muscle relaxation → glycinate. The carrier matters more than the price gap.
2. You take it as a generic mineral supplement and your gut is unbothered → citrate. Cheaper, equivalent absorption.
3. You take large doses (400+ mg elemental) in a single sitting → glycinate. Citrate at that dose is a laxative.
4. You're already taking a multivitamin with magnesium → check the form on the label. If it's oxide, supplement separately with glycinate. If it's citrate or chelated, you may not need to add anything.

What to ignore

• L-threonate marketing claims it crosses the blood-brain barrier better. The evidence is thin, the price is 4× glycinate, and there's no clinical endpoint study showing it outperforms glycinate on cognition.
• Magnesium aspartate is an older form largely replaced by glycinate. No reason to buy it new in 2026.
• Magnesium oxide is a laxative pretending to be a supplement. The 4% absorption rate makes it net more expensive per absorbed milligram than even premium chelates.

For the cheapest current deals on either form, jump to our cost-per-dose ranking on the magnesium nutrient page.