Magnesium bisglycinate: benefits and use

Magnesium bisglycinate, also called diglycinate in some publications, is a chelated salt: magnesium bound to two glycine molecules. On a label, what actually matters isn't the total weight of the compound, but the amount of elemental magnesium delivered per dose.

Magnesium takes part in numerous enzymatic reactions and is involved in muscle and nerve function, energy production, blood sugar regulation, blood pressure and bone health.

In the European Union, the authorised claim is that magnesium contributes to the reduction of tiredness, provided the product is at least a source of magnesium. That wording is far more cautious than the promises often seen online: it doesn't say a supplement "gives you energy" or treats unexplained fatigue.

An adequate magnesium intake mainly helps avoid a shortfall. EFSA sets adequate intakes at 350 mg/day for adult men and 300 mg/day for adult women, without concluding that needs increase during pregnancy or breastfeeding. These benchmarks cover total intake, diet included.

Not all forms of magnesium behave the same way. The NIH notes that more soluble forms, such as aspartate, citrate, lactate or chloride, tend to be better absorbed than oxide or sulfate. For bisglycinate specifically, the human data are more limited and more nuanced.

In a small trial in patients with ileal resection, magnesium diglycinate was not overall better absorbed than oxide, but it was better tolerated and better absorbed in patients whose absorption of oxide was lowest. In a 60-day randomized trial, the organic forms studied, including an amino-acid chelate, showed better absorption than oxide; citrate produced the best markers in that study. In a crossover trial in 40 adults, bisglycinate did not produce a significant rise in plasma magnesium at the measured time points, unlike some of the other forms tested.

Magnesium bisglycinate is often marketed for sleep. A 2025 randomized trial observed a modest improvement in insomnia severity with 250 mg/day of elemental magnesium as bisglycinate over 4 weeks, with a small effect size. That's an interesting signal, not definitive proof.

The NCCIH considers the available data on magnesium supplements for insomnia and sleep disorders to remain insufficiently robust to conclude they are effective. For cramps, caution matters even more: the Cochrane evidence does not support presenting magnesium as a reliable solution against muscle cramps; the effect is unlikely for idiopathic cramps, and the data remain uncertain in other contexts.

Start by looking at your diet: leafy greens, legumes, nuts, seeds and whole grains naturally provide magnesium. If a supplement is considered, the label should state the elemental magnesium per dose. Two capsules of "magnesium bisglycinate" from different brands can contain very different amounts of usable magnesium.

In adults, the NIH's upper limit for magnesium from supplements and medications is 350 mg/day; it does not apply to dietary magnesium. That doesn't mean 350 mg/day is a target to reach — it's a caution threshold for non-dietary intake.

Magnesium supplements can cause diarrhoea, nausea and abdominal cramps; they can also interact with bisphosphonates, certain antibiotics, diuretics and proton pump inhibitors. The risk of toxicity increases in particular with kidney impairment, since magnesium elimination relies heavily on the kidneys.