Which Magnesium Should You Take? A Straight Comparison

Form	Take it for	When	Evidence on this exact form
Glycinate	Sleep, calm, muscle	Evening	2025 RCT on bisglycinate for poor sleep
Malate	Daytime energy metabolism	Morning	Thinner — mechanistic rather than outcome trials
Complex	Both, one bottle	Either	Inherits from its two components

01Glycinate — the default

Magnesium bound to two glycine molecules. Well absorbed, and the least likely of any form to cause a laxative effect, which matters when the point is not waking up.

It is also the only one of ours with a trial on the exact form. A 2025 randomised placebo-controlled trial gave adults with poor sleep 250 mg of elemental magnesium as bisglycinate; insomnia severity fell 3.9 points versus 2.3 on placebo, with the benefit concentrated in people whose dietary magnesium was low to begin with.¹ The authors call the effect small, and the p-value was 0.049. We wrote that up properly in the best supplements for sleep.

Choose it if: you want magnesium and have not got a specific reason to want something else.

02Malate — the daytime one

Magnesium bound to malic acid, an intermediate in the cycle that produces ATP. That is the rationale for taking it in the morning rather than at night, and it is a mechanistic rationale rather than an outcome one — we are not going to pretend there is a body of malate-specific sleep or energy trials, because there is not.

What is true is that it does not have glycinate's settling quality, which makes it the better choice if you want magnesium during the day. Choosing by time of day goes into it.

Choose it if: you want magnesium in the morning, or glycinate makes you drowsy at the wrong hour.

03Complex — both, once

Magnesium Complex is bisglycinate and malate together. There is nothing new in it; the argument for it is purely that running two bottles for one mineral is inefficient. If your goal is sleep alone, glycinate on its own is the cleaner and cheaper choice.

Choose it if: you want cover across the day and would rather take one capsule than two.

04Threonate — the one we have not made, and why

Magnesium L-threonate is the form developed to raise magnesium in the brain rather than just the blood, and it is aimed at cognition rather than sleep or muscle. We do not currently make it. Here is the honest reasoning, because you will find it on plenty of other shelves.

The evidence is real. A 2025 randomised, double-blind, placebo-controlled trial gave 100 adults aged 18 to 45 with poor sleep 2 g daily of Magtein® for six weeks and reported improvements in overall cognition, working memory and reaction time.² An earlier trial in older adults with cognitive complaints found a benefit over 12 weeks.³

And then three caveats.

One. The 2025 trial reported improvements in subjective sleep measures but not objective ones.² If you are buying it to sleep better, that distinction matters.

Two. That trial was funded by the company that owns the intellectual property in the compound, and that company also supplied the study product.² That does not make the result wrong. It does mean it should be weighted accordingly.

Three. A frequently cited 2022 study used a formula that also contained phosphatidylserine and vitamins C, D and B6.⁴ You cannot attribute that result to magnesium alone.

None of that makes threonate a bad product. It makes it a form whose evidence we would want to be stronger before we put our name and a certificate on it. If cognition is specifically your goal and you have read the three paragraphs above, it is a reasonable thing to buy — just not from us yet. We wrote more in what the premium is actually for.

05The two forms we deliberately do not make

Oxide is the most common magnesium on shelves and is absorbed at roughly four percent. It is effective as a laxative and largely ineffective as a magnesium supplement. Its appeal to manufacturers is that it is cheap and shows a big number on the label — the compound weight, not the elemental magnesium.

Citrate is genuinely well absorbed and perfectly reasonable. It also draws water into the bowel, which is useful if that is what you want and unwelcome if it is not.

06Read the elemental number, not the front

The single most useful habit with magnesium: the large number on the front of the bottle is usually the weight of the whole compound, and the magnesium itself is a fraction of it. The elemental figure is the one that matters and it is in the Supplement Facts panel. How to read a label in 30 seconds covers the rest.

All three are in the range, and every lot carries an independent certificate on the product page.

07Frequently asked questions

Which magnesium is best for sleep?

Glycinate. It is the form with a trial on the form, and the one least likely to disturb you for other reasons.¹

Do you sell magnesium threonate?

No. The evidence is genuine but comes with the three caveats above, and we would rather wait than put a certificate on something we are not yet convinced by.

Can I take two different magnesiums?

You can, but count the elemental total across both. Doubling up is the most common mistake we see.

Why does magnesium oxide exist if it is barely absorbed?

It is cheap, and its poor absorption is exactly what makes it work as a laxative. It is a legitimate product for that purpose and a poor one for repletion.

Should I take magnesium with food?

Not required. Consistency across weeks matters more than timing on any given day.

How long before I notice anything?

The sleep trial ran four weeks, the cognition trials six and twelve.^1,2,3 Judge it over weeks, not nights.

08References

1. Magnesium bisglycinate supplementation in healthy adults reporting poor sleep: a randomized, placebo-controlled trial. 2025. PMCID: PMC12412596.
2. Lopresti AL, Smith SJ. The effects of magnesium L-threonate (Magtein®) on cognitive performance and sleep quality in adults: a randomised, double-blind, placebo-controlled trial. Front Nutr. 2025;12:1729164. doi:10.3389/fnut.2025.1729164 — funded by Threotech Inc, which also provided the study product.
3. Liu G, Weinger JG, Lu ZL, Xue F, Sadeghpour S. 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.
4. Zhang C, Hu Q, Li S, et al. A Magtein®, magnesium L-threonate,-based formula improves brain cognitive functions in healthy Chinese adults. Nutrients. 2022;14(24):5235. doi:10.3390/nu14245235 — formula also contained phosphatidylserine and vitamins C, D and B6.
5. Uysal N, Kizildag S, Yuce Z, et al. Timeline (bioavailability) of magnesium compounds in hours: which magnesium compound works best? Biol Trace Elem Res. 2019;187(1):128–136. doi:10.1007/s12011-018-1351-9

*These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.