Quick answer: the type of magnesium matters less than the hype suggests, but it does change two things: how well it absorbs and what it does to your stomach. The NIH says forms that dissolve well, like citrate, chloride, lactate and aspartate, tend to absorb better than oxide and sulfate. Citrate is the one to pick for occasional constipation. Glycinate is the popular pick for sleep. Threonate, malate and taurate are heavily marketed, but the human evidence behind them is thin or company-funded.
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Key Findings
- The NIH says magnesium forms that dissolve well in liquid absorb better, and that citrate, lactate, aspartate and chloride tend to be more bioavailable than oxide and sulfate.
- Magnesium citrate is a saline laxative used for occasional, short-term constipation, according to MedlinePlus.
- Both human trials of magnesium L-threonate we found were funded by or run with companies that sell it, and the results were mixed.
- A 2019 evidence summary found magnesium with malic acid makes little or no difference to fibromyalgia pain.
- A 2020 Cochrane review says magnesium is unlikely to prevent muscle cramps in older adults.
- A 2017 review calls absorbing magnesium through the skin, like Epsom salt baths and sprays, scientifically unsupported.
- Adults need 310 to 420 mg a day from all sources. The upper limit for supplements is 350 mg a day.
Types of Magnesium Chart: What Each One Is For
| Type | Marketed for | What the evidence says | Watch out for |
|---|---|---|---|
| Glycinate (bisglycinate) | Sleep, stress, a gentle stomach | A 2025 trial of 155 adults tested 250 mg a day for sleep, and the magnesium group reported fewer side effects than the placebo group | Check the label for elemental magnesium, not the total weight |
| Citrate | Constipation, everyday use | Absorbs better than oxide (NIH). Used as a saline laxative for occasional constipation (MedlinePlus) | Loose stools, especially at higher doses |
| Oxide | Low price, heartburn | Lower bioavailability than citrate or chloride (NIH). Also used as an antacid (MedlinePlus) | More likely to cause diarrhea for the magnesium you absorb |
| Chloride | Absorption, sprays and oils | Absorbs better than oxide when swallowed (NIH) | Sprays and oils on the skin are not proven to work |
| L-threonate | Brain, memory, sleep | Two human trials: one for sleep in 80 adults, one for memory and sleep in 100 adults. Both had company funding, and some measures showed no difference | The trials used 1 to 2 grams of the compound a day, which is not the same as the elemental magnesium |
| Malate | Energy, muscle pain, fibromyalgia | Little or no difference for fibromyalgia pain, according to a 2019 evidence summary | Claims go far beyond the research |
| Taurate | Heart, blood pressure | The studies we found were mostly in animals | No solid human evidence yet |
| Sulfate (Epsom salt) | Baths, sore muscles | Lower bioavailability when swallowed (NIH). Absorbing it through the skin is scientifically unsupported (2017 review) | A bath may feel nice, but it is not a supplement |
Which Magnesium Is Best for What?
For sleep
Glycinate is the most popular pick, and it has a 2025 trial of 155 adults behind it. Threonate is marketed for sleep too, but its trials were company-funded. We cover the sleep research in detail in magnesium for sleep.
For constipation
Citrate. MedlinePlus says magnesium citrate is a saline laxative used to treat occasional constipation on a short-term basis. Use it for a short time only, and talk to your doctor if constipation keeps coming back. See how it compares in magnesium glycinate vs citrate.
For migraines
The NIH says the American Academy of Neurology and the American Headache Society have concluded that magnesium is probably effective for preventing migraines, although the data are limited. They do not name one best form, so ask your doctor about the dose.
For muscle cramps
Probably none. A 2020 Cochrane review of trials found it is unlikely that magnesium gives older adults meaningful protection from muscle cramps.
For the best absorption
Pick a form that dissolves well, like citrate, chloride, lactate or aspartate, over oxide or sulfate, the NIH says.
How Much Magnesium Do You Need?
- From all sources: 310 to 420 mg a day for adults, depending on age and sex (NIH).
- From supplements: no more than 350 mg a day for adults, not counting food (NIH).
- Read the label: look for the amount of elemental magnesium per serving. A capsule of “magnesium glycinate” weighs more than the magnesium inside it.
Too much from supplements can cause diarrhea, nausea and stomach cramps, the NIH says. People with kidney disease should talk to a doctor first. More in magnesium glycinate side effects.
Magnesium Picks by Type
These are the products our magnesium guides already cover. Check the label for the elemental magnesium per serving before you buy.
- Glycinate: Nature Made Magnesium Glycinate or Thorne Magnesium Bisglycinate. Check the current price.
- Citrate: Nature Made Magnesium Citrate or NOW Magnesium Citrate. Check the current price.
- L-threonate: Life Extension Neuro-Mag, if you want to try it despite the thin evidence. Check the current price.
We do not recommend a malate or taurate product, because the human evidence is too weak to say they beat cheaper forms.
Want the deeper investigation? Our ebook The Supplement Scam Bible shows how supplement labels, dosage claims and “clinically proven” wording mislead, and how to read a label for what it actually says. Get the ebook ($19) → See all our ebooks →
How We Researched This
We do not lab-test products. We read the NIH Office of Dietary Supplements fact sheet, MedlinePlus drug guides, a 2020 Cochrane review, a 2019 evidence summary, a 2017 review on skin absorption and the human trials of magnesium L-threonate, including who funded them. We checked each claim against the original source.
Frequently Asked Questions
What are the different types of magnesium?
The main types are glycinate, citrate, oxide, chloride, L-threonate, malate, taurate and sulfate. The NIH says forms that dissolve well, like citrate and chloride, tend to absorb better than oxide and sulfate.
Which type of magnesium is best?
It depends on why you take it. Citrate is used for occasional constipation, glycinate is a popular pick for sleep, and citrate or chloride absorb better than oxide. Threonate, malate and taurate have thin or company-funded human evidence.
Which magnesium is best for sleep?
Glycinate is the most popular choice, and a 2025 trial of 155 adults tested 250 mg a day of magnesium bisglycinate for sleep. Threonate is also marketed for sleep, but its trials were company-funded and some sleep measures showed no difference from placebo.
What is magnesium malate good for?
It is marketed for energy and muscle pain, but a 2019 evidence summary found that magnesium with malic acid makes little or no difference to fibromyalgia pain. There is no strong proof it works better than cheaper forms.
Do Epsom salt baths raise your magnesium?
There is no good evidence that they do. A 2017 review concluded that absorbing magnesium through the skin is scientifically unsupported. Epsom salt is magnesium sulfate, which the NIH says is also poorly absorbed when swallowed.
How much magnesium should I take a day?
Adults need 310 to 420 mg a day from all sources, depending on age and sex. The NIH sets the upper limit for supplements at 350 mg a day for adults, not counting food. Too much can cause diarrhea, nausea and stomach cramps.
Sources
- NIH Office of Dietary Supplements: Magnesium, Fact Sheet for Health Professionals
- MedlinePlus: Magnesium Citrate
- MedlinePlus: Magnesium Oxide
- Garrison et al. (2020), Cochrane Database of Systematic Reviews: Magnesium for skeletal muscle cramps
- Ferreira et al. (2019), Medwave: Magnesium and malic acid supplement for fibromyalgia
- Gröber et al. (2017), Nutrients: Myth or Reality, Transdermal Magnesium?
- Hausenblas et al. (2024), Sleep Medicine X: Magnesium-L-threonate and sleep quality, a randomized controlled trial
- Lopresti et al. (2025), Frontiers in Nutrition: Magnesium L-threonate (Magtein) on cognitive performance and sleep quality, a randomised trial
- Schuster et al. (2025), Nature and Science of Sleep: Magnesium bisglycinate supplementation in adults reporting poor sleep
This article is for general information, not medical advice. If you have a health condition or take medication, talk to your doctor first. Read our Health Disclaimer.
