Magtein® L-Threonate Plus by Integrative Therapeutics

Magnesium L-threonate is the form people choose for the brain, not for muscles or regularity. It suits adults who want to support memory, focus and mental sharpness, often in midlife and later, and who are prepared to take it daily for a couple of months before judging. It is not the form for raising a low Magnesium or RBC Magnesium result: a serving supplies 144 mg of magnesium, a modest amount next to typical glycinate or citrate products.

Magtein is a branded magnesium L-threonate, which is magnesium bound to a metabolite of vitamin C. In animal studies this form raised magnesium in the fluid around the brain more than other forms did, and magnesium there helps regulate the receptors nerve cells use in learning and memory. Human evidence is limited to a few small trials, which reported better scores on cognitive tests. The front label's claim is support for cognitive performance, including executive function and short-term memory. This version adds vitamin C and vitamin D3.

One serving is 3 capsules, which provides 144 mg of magnesium from 2,000 mg of Magtein, plus 60 mg of vitamin C and 10 mcg (400 IU) of vitamin D3. The label directs adults to take 3 capsules daily and says they are best taken in divided doses: 1 capsule in the morning and 2 capsules one hour before bedtime. It says not to exceed that, and that the product is not formulated for children. A bottle of 90 capsules holds 30 servings.

Take magnesium at least 2 hours apart from levothyroxine, tetracycline or quinolone antibiotics and bisphosphonates, because it binds them in the gut. The kidneys clear magnesium, which is why the label tells people with kidney disease, and anyone taking medications, to consult a healthcare professional before use. Count the 400 IU of vitamin D3 toward your total if you take other vitamin D products. The label says not to take it if you are pregnant or nursing.

Expect to take it daily for 6–12 weeks before deciding whether it helps; effects, where they occur, are subtle. Drowsiness and headache are the side effects reported most, usually in the first week. Compared with glycinate or citrate, L-threonate delivers less magnesium per serving, so choose it for its cognitive aim and choose another form to correct a low level or for muscle relaxation. Memory changes that worry you deserve a clinician's assessment, not a supplement.