A well done summary of differences between Magnesium L-Threonate and Glycinate.

Amy Brownstein writes up a nice piece I am sharing with my readers today. What drives decision to use one of two different Magnesium preparations.

Magnesium L-Threonate vs. Magnesium Glycinate: Which Is Right for you?

By Amy Brownstein, MS, RDN original posted January 13, 2025

Medically reviewed by Suzanne Fisher, RD for VeryWell Health

By one estimate, 68% of Americans consume less than the recommended dietary amount of magnesium. Magnesium is essential for over 300 bodily functions and affects heart disease risk, blood pressure, type 2 diabetes, mental health (depression and anxiety), sleep, and cognitive health.¹

Magnesium L-threonate and magnesium glycinate are two popular magnesium supplement forms. Deciding which supplement to choose depends on your health goals and how you intend to use it. Magnesium L-threonate contains magnesium and L-threonate, while magnesium glycinate combines magnesium with the amino acid glycine.²³ Both forms of magnesium are popular supplement options, providing specific advantages to health. While both forms can replenish magnesium levels, their specific effects can vary.

In the United States, the Food and Drug Administration (FDA) does not regulate dietary supplements the way it regulates prescription medications. As a result, some supplement products may not contain the ingredients listed on the label. When choosing a supplement, look for products independently tested or certified by organizations such as NSF, U.S. Pharmacopeia, or ConsumerLab.com. For personalized guidance, consult your healthcare provider, registered dietitian nutritionist (RD or RDN), or pharmacist.

Key Differences

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Their different chemical compositions affect magnesium glycinate and L-threonate’s health benefits and how they should be used.²³ Unlike other forms, magnesium L-threonate can cross the blood-brain barrier, which may explain its beneficial effects on cognitive function and health.⁴

Both magnesium glycinate and magnesium L-threonate share some health benefits, such as restoring circulating magnesium levels and relieving constipation. Additionally, both magnesium forms may support sleep by facilitating relaxation and calmness.⁵⁶⁴

Magnesium affects gamma-aminobutyric acid (GABA) neurotransmitters and N-methyl-D-aspartate (NMDA) receptors that help neurons communicate. Magnesium inhibits NMDA activity and promotes the activity of GABA neurotransmitters to foster a sense of relaxation and calmness. Additionally, magnesium may contribute to sleep by increasing melatonin and reducing cortisol levels.⁶⁷

Research suggests that the benefits of magnesium L-threonate and magnesium glycinate depend on the individual. Some people may experience improvements earlier, while others may notice little change overall.⁸

The best time to take magnesium L-threonate or magnesium glycinate may depend on its intended use. Ultimately, though, the best time of day is whatever time works for you. Consistency is key to reap the benefits of magnesium supplements.

Reasons to Take Magnesium L-Threonate

Magnesium L-threonate was discovered in 2010, so it is still a relatively new supplement. Preliminary research is promising, but more human studies are warranted to understand magnesium L-threonate’s health benefits fully.

1. Cognitive Enhancement

Mouse models show that magnesium L-threonate protects against neurodegeneration by supporting the ability of neurons to form connections (synaptic plasticity).¹¹ In human research, magnesium L-threonate improved deep sleep, enhancing energy, alertness, mood, memory, and learning.⁴

Other research shows that magnesium L-threonate boosts cognitive function and ability.¹²⁸ Still, additional research in humans is needed.

2. Anxiety, Stress, and Depression

Some research indicates low magnesium levels are associated with an increased risk of anxiety; supplementation may improve stress and anxiety levels.⁴ Magnesium’s effect on enhancing memory and synaptic density may help ease mental health issues. Emerging research on magnesium L-threonate for depression shows promise, but more studies are needed.¹³¹²

3. Sleep Quality

Magnesium is essential for the body’s production of melatonin, a hormone that helps you fall asleep. Magnesium’s effect on GABA promotes relaxation and calmness, facilitating sleep. One study observed improved deep sleep—the most restorative and rejuvenating sleep period—with 1,000 milligrams (mg) of magnesium L-threonate daily.⁴

4. Attention Deficit Hyperactivity Disorder (ADHD)

According to one study, supplementing with magnesium L-threonate for 12 weeks is associated with a 25% reduction in ADHD symptoms. Some studies suggest lower circulating magnesium levels exist in people with ADHD. Although promising, additional research is needed, as only small studies exist.¹³

5. Pain Management

Supplementing with magnesium L-threonate alongside other pain management medications reduced the dosage of opioid medications and delayed morphine tolerance among individuals undergoing cancer treatment. Still, more studies are needed.¹⁴

Common Uses for Magnesium Glycinate

Magnesium glycinate is a common magnesium supplement, given its versatility and high bioavailability.

1. Sleep Quality

Limited research exists on magnesium glycinate specifically for sleep. Individually, glycine and magnesium contribute to sleep. Combining glycine and magnesium may enhance their sleep-promoting effects. Some research suggests glycine promotes sleep and boosts sleep quality, reducing sleepiness and fatigue the following day.⁵

Studies show a link between sleep and magnesium levels, with a higher magnesium status associated with better sleep quality, duration, and efficiency.⁶

Arab A, Rafie N, Amani R, et al. The role of magnesium in sleep health: a systematic review of available literature. Biol Trace Elem Res. 2023;201(1):121-128. doi:10.1007/s12011-022-03162-1

¹⁵

2. Anxiety Relief and Depression

Magnesium regulates the hypothalamic pituitary adrenal axis (HPAA), which is involved in the body’s stress response. Magnesium lessens HPAA activity, contributing to reduced anxiety.¹ Additionally, magnesium is an essential coenzyme in converting the amino acid tryptophan to serotonin, a neurotransmitter vital for mood. Supplementing with magnesium glycinate improves depression symptoms.¹⁶

However, despite the potential benefit of magnesium for anxiety, other research is less conclusive. Ultimately, additional studies are needed.¹

3. Magnesium Deficiency

Regarding magnesium deficiency, mouse models have shown that magnesium glycinate increases circulating magnesium levels better than other supplement forms.¹⁷ Magnesium glycinate is commonly recommended for humans for its high bioavailability and potential to raise serum magnesium levels.¹

4. Regulating Blood Sugar

Magnesium is an essential coenzyme for carbohydrate metabolism. Magnesium deficiency impacts cells’ ability to use glucose. It may also improve insulin release from the pancreas, which helps reduce blood sugar levels. Magnesium supplementation may improve fasting blood sugar in people with diabetes. It may also benefit fasting and post-meal (postprandial) blood sugar among individuals at a high risk of developing type 2 diabetes.¹⁸¹⁰

However, despite promising research on the link between magnesium levels and diabetes among individuals with prediabetes (blood sugar levels that are not high enough to be considered diabetes) or a high risk of diabetes, the American Diabetes Association still does not recommend the use of magnesium supplements to improve blood sugar control due to inconclusive evidence.¹⁹

5. Heartburn Prevention

Many antacids for heartburn contain magnesium.²⁰ Magnesium salts reduce stomach acidity. Additionally, magnesium attaches to bile acids to prevent damage to the esophagus due to high acidity levels.²¹ Most antacids use other forms of magnesium, but there is potential for magnesium glycinate to prevent heartburn.

How to Choose

Because both magnesium L-threonate and magnesium glycinate contain magnesium, they will raise circulating magnesium levels. Still, other factors can influence your choice.

• Consider the Intended Use: Magnesium L-threonate crosses the blood-brain barrier, so it may be the better choice for cognitive issues. Both magnesium L-threonate and magnesium glycinate may promote sleep. However, there is no consensus on the best form of magnesium for anxiety.¹

• Consider the Amount of Magnesium in Each Supplement: When choosing a magnesium supplement, look at the amount of magnesium in each form of the product. The supplement size may not reflect its magnesium content. For example, a 414 mg magnesium supplement may contain only 250 mg of elemental magnesium.²² L-threonate comprises most of the magnesium L-threonate compound. A 3,000 mg dose of magnesium L-threonate equals roughly 2,730 mg of L-threonate and 250 mg of magnesium.⁹

• Opt for Supplements That Are Independently Tested: Third-party testing helps ensure that your supplement contains the ingredients listed in the stated amounts. Look for supplements that have been tested by trusted organizations.

Recommended Daily Amount **

The Recommended Dietary Allowance (RDA) represents the average daily magnesium intake necessary to meet the nutritional needs of almost all healthy individuals. Although it varies depending on age, sex, and life stage, the RDA for magnesium is the same regardless of the supplement form.

The RDA for magnesium regarding age is as follows:

• Females, 19 to 30 years: 310 milligrams (mg)

• Males, 19 to 30 years: 400 mg

• Pregnancy, 19 to 30: 350 mg

• Lactation, 19 to 30: 310 mg

• Females age 31 and older: 320 mg

• Males age 31 and older: 420 mg

• Pregnancy, 31 and older: 360 mg

• Lactation, 31 and older: 320 mg²³

• ** RDA is not something Functional Practitioners use a guidelines; our recommendations usually exceed the RDA. [JP]

Potential Side Effects

Potential side effects of magnesium include diarrhea, abdominal pain, and cramping. Although you can take magnesium with or without food, taking it with food may reduce the chance of diarrhea.³

Magnesium supplements can interact with certain medications. People taking any of the following medications should consult their healthcare provider before starting magnesium L-threonate or magnesium glycinate:

• Proton pump inhibitors (for acid reflux)

• Bisphosphonates (for osteoporosis)

• Diuretics

• Antibiotics²³

Magnesium may also compete with zinc and calcium supplements. To avoid interactions, take magnesium L-threonate or magnesium glycinate separately from zinc and calcium.²³

Magnesium has a tolerable upper intake level (UL) of 350 mg, the maximum dosage unlikely to cause any side effects. Any adverse effects of magnesium usually occur from high-dose supplementation and not food. You are unlikely to reach the UL alone through food sources.²³

Although clinical research uses magnesium doses up to 1 gram daily, it is not recommended to exceed the UL.⁶ Supplementing in amounts greater than the UL can cause adverse effects.

Who Should Avoid Taking Magnesium Supplements?

Magnesium supplements are generally considered safe when taken at their recommended dosages. Still, some individuals, such as those with the following characteristics, should exercise caution before supplementing with magnesium:

• Magnesium allergy: People allergic to magnesium L-threonate, magnesium glycinate, or its parts should avoid it.

• Kidney disease: People with kidney disease should avoid magnesium supplements, as damaged kidneys may be unable to regulate magnesium levels effectively.

• Pregnancy and breastfeeding: People who are pregnant or breastfeeding should consult their healthcare provider before starting a magnesium supplement. Although generally considered safe with pregnancy and breastfeeding, little is known about the effects of magnesium during these life stages.²³

Summary

Magnesium glycinate and magnesium L-threonate are two forms of magnesium supplements. Both supplements increase circulating magnesium levels, support sleep, and may reduce anxiety.

Because magnesium L-threonate can cross the blood-brain barrier, its additional benefits focus on cognitive health. Magnesium glycinate may have more widespread effects, influencing blood sugar and heartburn.

If you’re considering starting a magnesium glycinate or L-threonate supplement, consult your healthcare provider to determine the best form and dosage for you. Dosages for magnesium glycinate and L-threonate differ, and which one you should take and how much depends on your intended use.

Americans are greatly magnesium deficient in general. [JP]

References:

Verywell Health uses only high-quality sources, including peer-reviewed studies, to support the facts within our articles. Read our editorial process to learn more about how we fact-check and keep our content accurate, reliable, and trustworthy.

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