Not all magnesium is the same: glycinate vs oxide

Magnesium is one of the most common supplement ingredients on the shelf, and one of the most inconsistently formulated. Two products can both say "magnesium 300mg" and behave very differently.

The form matters more than the number

Magnesium oxide is cheap and dense, which makes it attractive on a label — you can claim a high milligram count in a small capsule. The tradeoff is absorption. A large share passes through undigested, which is also why it has a reputation for digestive upset.

Magnesium glycinate binds magnesium to glycine, an amino acid. It absorbs more readily and is markedly gentler on the stomach. Glycine has a mild calming character of its own, which is a useful fit for an evening formula.

What to look for on a label

Check whether the label names the form at all. "Magnesium 400mg" with no form stated is a warning sign. So is a "proprietary blend" that lists magnesium alongside other ingredients without breaking out the doses.

The honest version of a label tells you the compound and the amount: magnesium glycinate, 300mg. That's what we print on Calm, alongside L-Theanine 200mg, Apigenin 50mg and Glycine 500mg.

The practical takeaway

If magnesium hasn't worked for you before, it's worth checking which form you were taking. The mineral may not have been the problem.