Magnesium L-Threonate

This is the magnesium form our naturopaths get asked about most, so here are the questions they ask in store, along with what the research and Australian rules actually say.

A good fit if

• You're choosing it for the memory and thinking research specifically, and you've looked at who funded that research
• You already get enough magnesium, and this is an extra rather than your main source
• You value the brain research, which is still unproven, more than the amount of magnesium you get
• You're comfortable with a product that isn't an AUST L listed medicine and doesn't carry the labelling that comes with one
• Your kidneys are healthy and you don't take any medicine that needs to be spaced away from minerals

Check with us first if

• Your real goal is fixing a low magnesium intake. A listed magnesium medicine will do that far better, and this form will barely shift it.
• The product isn't an AUST L listed medicine, so the quality, labelling and side-effect reporting rules for listed medicines don't apply to it. It's worth knowing before you buy.
• You take other supplements with vitamin C or its breakdown products. Threonic acid is a vitamin C breakdown product, and taking both together hasn't been studied.
• You take bisphosphonates, tetracycline or quinolone antibiotics, diuretics (water tablets) or long-term reflux medicine (a proton pump inhibitor). The spacing and monitoring apply to every form of magnesium and are set out on our magnesium page.
• Your memory or concentration has changed noticeably. That's a reason to see your doctor first, not to try a supplement.
• You take any prescription medicine. A quick check with your doctor, pharmacist or our naturopaths first is the sensible step.

• Magnesium L-threonate (not in Schedule 1). Best known for: Positioned for the brain and thinking, and the only magnesium form missing from the permitted list. Absorption: Absorbed as a magnesium salt; its distinctive claim is about getting into the brain, which has only been tested directly in animals. Typical use: Powders and capsules supplying 1 to 2 g of compound, often taken in the evening.
• Calcium L-threonate (Schedule 1 item 1092). Best known for: Shows that threonate itself isn't excluded from Australian listed medicines. Absorption: Not comparable. This is a calcium product, listed with the single requirement that it be taken by mouth. Typical use: Included here only to show it's the magnesium pairing, not the carrier, that isn't listed.
• Magnesium methioninate (item 3164) and magnesium lysinate (item 3163). Best known for: True amino acid salts of magnesium, which are listed. Absorption: Chelated forms that behave like other chelates. Typical use: Mentioned because threonate is often mistaken for an amino acid salt. Threonic acid is a sugar acid, not threonine.
• Magnesium glycinate. Best known for: The listed chelate people compare threonate with for evening use. Absorption: Chelated to glycine and well tolerated at larger doses. Typical use: Supplies far more elemental magnesium in each capsule.
• Magnesium oxide. Best known for: The high-magnesium end of the comparison. Absorption: Poor, but it carries roughly eight times more magnesium, gram for gram of compound, than threonate. Typical use: The reference point threonate is usually compared against.

Reference values. The NHMRC's recommended amounts are for actual (elemental) magnesium, and the full list by age and sex is on our magnesium page. With threonate, the conversion really matters. It's only about seven per cent magnesium, so a 2 g serve of magnesium L-threonate gives you about 144 mg of magnesium (under half the adult recommended amount, from a whole scoop of powder).

Typical supplemental range. Australian labels are based on 1 g to 2 g of the compound per serve, with 76 mg to 144 mg of actual magnesium listed underneath. The published human trials used 1.5 g a day for people weighing 50 to 70 kg and 2 g a day for people weighing 70 to 100 kg over 12 weeks, and 2 g a day over six weeks.

Upper level. The NHMRC upper limit for magnesium from supplements is on our magnesium page, and it applies to the actual magnesium from any source. At label doses threonate is well below it, but that's because it contains so little magnesium, not because it's extra safe.

Worth knowing. With this form, the weight on the front of the pack is more than ten times the magnesium you actually get, so a 60 g tub gives you a month of magnesium at a small fraction of your daily recommended amount. If your goal is simply getting enough magnesium, another form will do that better; people choose threonate for the brain research. What you need depends on your age, diet and health, so talk to one of our naturopaths.

Food first, where the diet allows it.

• No food supplies magnesium L-threonate: it is a manufactured salt; dietary magnesium arrives bound to entirely different carriers
• Peanuts, oil roasted: about 63 mg of magnesium per quarter cup
• Shredded wheat cereal: about 61 mg per two large biscuits
• Chicken breast, roasted: about 22 mg per 85 g
• White rice, cooked: about 10 mg per half cup
• Carrot, raw: about 7 mg per medium carrot

If any of these sound like you, talk to one of our naturopaths or your doctor before you start.

• Reduced kidney function or kidney failure. Your body can't clear excess magnesium, so it can build up; don't supplement without medical supervision.
• Pregnancy and breastfeeding. Australian labels state these products aren't intended for pregnant or breastfeeding women, and no trial has looked at this form in pregnancy.
• Children and teenagers. Australian labels state these products aren't intended for children, and all published trials were in adults.
• If you're relying on it to fix a low magnesium intake. At roughly seven per cent magnesium, it's poorly suited to that job.
• If you're buying it as a listed medicine. Magnesium L-threonate isn't in Schedule 1, so products containing it aren't AUST L listed medicines and aren't labelled as such.
• Bisphosphonates, tetracycline and quinolone antibiotics, diuretics and long-term proton pump inhibitors. See our magnesium page.
• Taking more than the label dose. Extremely high intakes can lead to an irregular heartbeat and cardiac arrest.
• A noticeable change in memory or concentration. That's a reason to see a doctor, not to start a supplement.
• If you take prescription medicines, check with your doctor, pharmacist or our naturopaths before you start.