Magnesium Threonate vs Magnesium Glycinate: Which One Should You Choose?

01Basics

Why magnesium matters

Magnesium is involved in hundreds of reactions in the body, including energy production, muscle and nerve function, blood sugar control, bone health and the regulation of sleep. Adults need roughly 270 to 420 mg a day depending on age and sex. Good sources include nuts, seeds, wholegrains, legumes, leafy greens and some mineral waters; see drinks high in magnesium.

Low intake is common in diets high in processed foods. Certain medicines (such as long-term proton pump inhibitors and some diuretics), alcohol, diabetes and digestive conditions also increase the risk of deficiency.

02Glycinate

Magnesium glycinate

• What it is: magnesium bound to glycine, an amino acid with calming effects in the nervous system.
• Absorption: good, and less likely than other forms to cause diarrhoea.
• Elemental magnesium: about 14 percent of the weight of the compound, so a typical capsule gives a useful dose.
• Used for: correcting low intake, muscle cramps, and as part of routines for sleep and stress.
• Evidence: magnesium in general has modest evidence for sleep quality in older adults and people with low magnesium; specific trials of the glycinate form are limited.
• Price: moderate.

03Threonate

Magnesium L-threonate

• What it is: magnesium bound to threonic acid, a breakdown product of vitamin C.
• Brain levels: animal studies found that it raised magnesium in the brain and improved learning and memory, which led to its development as a supplement.
• Elemental magnesium: only about 7 to 8 percent, so a typical daily dose provides around 140 mg of magnesium.
• Used for: memory, focus and sleep.
• Evidence: a few small human trials suggest possible benefits for cognitive function and sleep, but they are short and often industry-funded. Larger independent studies are needed.
• Price: higher than most other forms.

04Compare

Threonate vs glycinate side by side

• Magnesium per dose: glycinate provides more; threonate provides less.
• Digestive tolerance: both are generally well tolerated.
• Sleep and relaxation: glycinate is the usual practical choice; threonate has limited evidence.
• Memory and cognition: threonate is the form studied for this, with preliminary evidence.
• Correcting low magnesium: glycinate, because it delivers more elemental magnesium.
• Cost: glycinate is cheaper.

Magnesium citrate is another well-absorbed option but has a stronger laxative effect, and magnesium oxide is cheap but less well absorbed.

05Sleep

Which is better for sleep and anxiety?

For most people looking for help with sleep or stress, magnesium glycinate is the more practical option because it is gentle, affordable and provides more magnesium. Benefits are most likely if your intake was low to begin with. Magnesium is not a sedative and is not a treatment for insomnia disorder or anxiety disorders, which respond best to approaches such as cognitive behavioural therapy. See over-the-counter sleep aids and valerian root for sleep.

06Dose

Dose and timing

• Check the label for elemental magnesium, not the weight of the compound.
• Typical supplement doses are 100 to 350 mg of elemental magnesium a day.
• The upper limit from supplements for adults is 350 mg a day unless a doctor advises otherwise; magnesium from food does not count towards this limit.
• Taking it in the evening is common when the aim is sleep; with food it may be better tolerated.
• Separate magnesium from some antibiotics, thyroid medication and osteoporosis medicines by a few hours.

07Safety

Side effects and who should be careful

• Diarrhoea, nausea and stomach cramps, especially at higher doses.
• People with kidney disease should not take magnesium supplements without medical advice, because magnesium can build up.
• Interactions with certain antibiotics, bisphosphonates, thyroid medication and blood pressure medicines.
• Pregnancy and breastfeeding: check with a health professional first.
• Very high doses can cause low blood pressure, weakness and irregular heartbeat.

08Food first

Getting magnesium from food

• A handful of almonds, cashews or pumpkin seeds.
• Wholegrain bread, oats and brown rice instead of refined versions.
• Beans, lentils and chickpeas several times a week.
• Spinach, chard and other leafy greens.
• Dark chocolate in moderation, bananas and avocado.

A dietitian can review your diet and decide whether a supplement is useful.

09Summary

Key points to remember

• Glycinate delivers more magnesium, is gentle and is the practical choice for most.
• Threonate is studied for the brain but evidence in humans is still limited.
• Neither treats insomnia or anxiety on its own.
• Food comes first; check with a doctor if you have kidney disease or take regular medication.