Magnesium Glycinate vs. Citrate vs. L-Threonate: Which One Should You Take?

Magnesium Glycinate vs. Citrate vs. L-Threonate: Which One Should You Take?

If you've decided to try magnesium, the next question comes quickly: Which kind?

Magnesium glycinate, magnesium citrate and magnesium L-threonate are three of the forms you're most likely to encounter, and they're often marketed as though they're interchangeable.

They're not.

The best choice depends on why you're considering magnesium, how your body tolerates it and what you're willing to spend. The research behind the different forms also isn't equally strong, despite what some supplement labels and social-media posts would have you believe.

Here's how I think about the three.

Magnesium glycinate: the popular choice for sleep

Magnesium glycinate, also called magnesium bisglycinate, combines magnesium with the amino acid glycine. It has become particularly popular with people taking magnesium for sleep and relaxation.

There is some evidence supporting that use, although I wouldn't oversell it.

A 2025 randomized, double-blind, placebo-controlled trial studied 155 adults who reported poor sleep. Participants taking magnesium bisglycinate providing 250 mg of elemental magnesium daily for four weeks had a greater improvement in insomnia severity than those taking placebo, but the effect was small. The researchers described the improvement as modest.

That's useful information. It doesn't make magnesium glycinate a sleeping pill.

One reason people may prefer glycinate is that it is generally chosen when they want magnesium without the more noticeable bowel-loosening effect associated with forms such as citrate.

If sleep is your primary concern, glycinate may be a reasonable form to investigate. But persistent sleep problems deserve more than a supplement recommendation. Sleep apnea, medications, pain, alcohol, anxiety, restless legs and other problems can all interfere with sleep.

Magnesium citrate: particularly useful when constipation is part of the picture

Magnesium citrate combines magnesium with citric acid.

The National Institutes of Health lists citrate among forms of magnesium that tend to be more readily absorbed than magnesium oxide and magnesium sulfate.

It can also loosen the bowels.

That's not necessarily a side effect if constipation is one of the reasons you're interested in magnesium. In that situation, citrate may offer an advantage.

But if you already have loose stools or a sensitive gastrointestinal system, the same property can make citrate a poor choice.

This is why I don't particularly like the question, What's the best magnesium?

Best for what?

The feature that makes one form useful for one person can make it the wrong form for someone else.

Magnesium L-threonate: interesting research, bigger price tag

Magnesium L-threonate is the form you're most likely to see promoted for cognition and “brain health.”

This one interests me. I use it myself.

But what I personally choose to take and what scientific research has actually established are two different things.

A 2024 randomized controlled trial involving 80 adults with self-reported sleep problems found improvements in several measures of sleep and daytime functioning after 21 days of magnesium L-threonate supplementation.

More recent randomized, double-blind, placebo-controlled research involving 100 adults ages 18–45 found improvements in some measures of cognitive performance, including working and episodic memory and reaction time, after six weeks of magnesium L-threonate. Not every cognitive measure improved, however, and the study did not establish the sweeping brain-health benefits sometimes suggested in supplement marketing.

The research is interesting enough to keep watching.

It is not evidence that magnesium L-threonate prevents Alzheimer's disease or dementia, and I wouldn't pay its considerably higher price because someone on social media promised that it does.

I take it because I'm interested in the emerging research and have made that decision for myself. That's not evidence that you need it.

Glycinate vs. citrate vs. L-threonate

If you want the short version:

Magnesium glycinate/bisglycinate: Often chosen for sleep and relaxation and generally favored by people who want to avoid the laxative effect of some other forms. Evidence for improving sleep exists, but the demonstrated benefit so far is modest.

Magnesium citrate: Relatively well absorbed and can loosen the bowels. That may make it particularly useful when constipation is also an issue.

Magnesium L-threonate: The most interesting of these three for emerging cognition and sleep research, but also generally more expensive. The evidence is still developing and doesn't support the miracle-brain claims sometimes made for it.

There isn't one winner because they're being used for different reasons.

Before you compare prices, compare elemental magnesium

This is where supplement labels can make shopping unnecessarily confusing.

The amount of a magnesium compound in a product isn't the same thing as the amount of actual magnesium you're getting.

Look at the Supplement Facts panel for elemental magnesium.

That's the amount you should use when comparing products.

Also check the serving size. One product may provide its stated amount in one capsule while another requires two or three capsules.

So when comparing two bottles, I look at:

Form of magnesium. Elemental magnesium per serving. Capsules per serving. Other ingredients. Number of servings. Price.

The cheapest bottle isn't necessarily the least expensive way to get the formulation and dose you're looking for.

Do you need magnesium in the first place?

That's a different question, and I've already written about it in more detail.

My article Magnesium Is Everywhere Right Now. Do You Actually Need It? looks at magnesium intake, food sources, supplementation, safety and some of the reasons people may—or may not—need additional magnesium.

Testing can sometimes provide useful information too, although serum magnesium has limitations and can't tell us everything about the body's magnesium stores.

If you're interested in testing before simply adding another supplement, visit my Lab Results and Supplements section on TotalWellCoach. That's where I explain how I think about using laboratory information to make more informed supplement decisions and provide access to testing through my Ulta Lab Tests affiliate link.

Ready to compare magnesium supplements?

I don't believe everyone needs to buy the same supplement from the same company.

I provide access to three professional supplement storefronts: Fullscript, Metagenics and Wholescripts.

Rather than giving you one product link and telling you that's the magnesium to buy, I'd rather give you choices.

Visit my Shop Supplements page, choose one of the storefronts and create or sign into your customer account.

Then search for:

Magnesium glycinate or magnesium bisglycinate

Magnesium citrate

Magnesium L-threonate

You can search the same form in more than one storefront and compare the professional brands, formulations, elemental magnesium per serving and retail prices available to you.

I may tell you which products or formulations I personally use. That doesn't mean you have to buy the same ones.

I want you to have choices.

If glycinate fits what you're trying to accomplish, compare glycinate. If constipation is part of the reason you're considering magnesium, look more closely at citrate. If you're interested in L-threonate because of the emerging cognition research, look at L-threonate—but look at the evidence and the price before deciding whether it's worth the premium.

The question isn't simply, Which magnesium is best?

It's which form makes sense for what you're actually trying to accomplish.

Sources

National Institutes of Health, Office of Dietary Supplements. Magnesium Fact Sheet for Health Professionals.

National Institutes of Health, Office of Dietary Supplements. Magnesium Fact Sheet for Consumers.

Schuster J, Cycelskij I, Lopresti A, Hahn A. Magnesium Bisglycinate Supplementation in Healthy Adults Reporting Poor Sleep: A Randomized, Placebo-Controlled Trial. Nature and Science of Sleep, 2025.

Magnesium-L-threonate improves sleep quality and daytime functioning in adults with self-reported sleep problems: A randomized controlled trial, 2024.

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. Frontiers in Nutrition.