Walk down a supplement aisle and you'll find eight products that all say magnesium on the front and eight different second words underneath. Glycinate. Citrate. Oxide. Threonate. Malate. Taurate.

They aren't interchangeable. The second word tells you what the magnesium is bound to, and that binding determines how much of it your body actually absorbs, how it behaves in your gut, and what it's reasonably useful for. Buying the wrong one is how people conclude magnesium did nothing for them.

Here's the practical version.

Why magnesium gets talked about at all

Magnesium is involved in over 300 biochemical reactions in the body, covering nerve and muscle function, energy production, protein synthesis, blood pressure regulation, and blood sugar control. It's the fourth most abundant mineral in the human body.

It also appears to be something a lot of people don't get enough of. By one estimate, around 68 percent of Americans consume less than the recommended dietary amount. That figure gets repeated a lot in supplement marketing, so treat it as a rough signal rather than a precise fact, but the general direction is well supported.

Part of why magnesium is associated with calm comes down to how it interacts with two neurotransmitter systems. It inhibits NMDA receptor activity and supports GABA activity, and GABA is the brain's main inhibitory neurotransmitter. That's the mechanism usually cited behind the relaxation and sleep effects.

Magnesium glycinate

Magnesium bound to glycine, an amino acid.

That binding does two useful things. Glycine acts as a carrier that helps magnesium pass through the intestinal wall more easily, which means higher absorption. And it's gentle: glycinate is much less likely to cause the digestive upset that other forms are notorious for.

Glycine has its own calming properties, which is part of why this form gets recommended for relaxation and sleep rather than for other purposes. It's the form most often suggested for daily long-term use, precisely because you can take it consistently without your gut objecting.

The downsides are real but minor. It's one of the more expensive forms, and it's less widely stocked than the cheap options.

You'll also see magnesium bisglycinate on labels. Functionally it's the same thing; bisglycinate refers to two glycine molecules bound to the magnesium, and the two names get used interchangeably in practice.

Best for: daily use, relaxation, sleep, sensitive stomachs.

Magnesium citrate

Magnesium bound to citric acid. Well absorbed, widely available, and cheaper than glycinate.

The distinguishing feature is that citrate draws water into the intestines, which makes it effective for constipation and digestion. That's a genuine benefit if that's what you want and a genuine problem if it isn't. Take too much citrate and you'll find out quickly.

Best for: digestion and constipation. Not the one to pick for nightly relaxation.

Magnesium oxide

The cheap one, and the most common in low-cost supplements.

It has a high percentage of elemental magnesium by weight, which looks good on a label. The catch is that it's poorly absorbed, so a large share of what you swallow passes through without doing much except pulling water along with it. It's the form most associated with the laxative effect people complain about.

If a magnesium supplement gave you an unpleasant afternoon, there's a reasonable chance it was oxide.

Best for: occasional constipation relief, and being inexpensive. Not much else.

Magnesium L-threonate

Magnesium bound to threonic acid, a metabolite of vitamin C. It was developed specifically to cross the blood-brain barrier more readily than other forms.

That's the pitch: higher brain magnesium, and research suggesting effects on memory, learning, and synaptic plasticity. It's the form aimed at cognitive function rather than muscle relaxation.

Worth being clear-eyed here. It's newer, more expensive, and the human evidence base is smaller than for the older forms. Interesting, not settled.

Best for: cognitive support, if you're willing to pay for a less established option.

Others you'll see

Malate is bound to malic acid and gets recommended for energy and muscle pain, with a thinner evidence base than the forms above. Taurate is bound to taurine and is usually pitched for cardiovascular support. Carbonate treats gastric issues and heartburn, and carries risks with daily use.

How to actually choose

Ask what you want it for, then work backwards.

Sleep, relaxation, daily use, sensitive stomach: glycinate.

Constipation: citrate.

Cognitive function and willing to experiment: threonate.

Lowest possible price and you don't mind the side effects: oxide, though you'd be better served spending slightly more.

One more thing worth checking on any label: the elemental magnesium content, not the total compound weight. A capsule listing 500mg of magnesium citrate does not contain 500mg of magnesium. The elemental number is the one that matters, and reputable products print it.

Why we use glycinate

SÜTHE uses magnesium glycinate, and the reasoning follows directly from everything above.

It's a drink meant for daily use, which rules out anything with a laxative effect. It's meant to support calm rather than digestion, which points at the glycine binding. And it needs to sit comfortably with people who might have two in a day, which rules out oxide entirely.

Glycinate costs more than the alternatives. That's the tradeoff, and we'd rather absorb the cost than list a cheaper form and hope nobody checks.

See the full ingredient breakdown.

Sources referenced

Brownstein, A. (2025). Magnesium L-Threonate vs. Magnesium Glycinate: Which Is Right for You? Medically reviewed by Suzanne Fisher, RD. VeryWell Health.

Seeking Health (2024). Magnesium Bisglycinate vs Glycinate: What's the Difference?

Berg, E. Magnesium Citrate vs. Glycinate, on gastrointestinal tolerance and long-term use.

This article is for general information and isn't medical advice. Talk to a healthcare provider before starting a supplement, particularly if you take medication or have kidney concerns.