Magnesium glycinate vs citrate, oxide and threonate

The Evening label carries two numbers: magnesium glycinate at 2,500 mg and elemental magnesium at 275 mg.

The larger number is the weight of the full compound. The smaller number is the amount of magnesium within it. Understanding that difference lets you compare magnesium labels accurately.

What is elemental magnesium?

Elemental magnesium is the weight of the magnesium metal itself, separated from whatever it is bound to. A magnesium supplement is never pure magnesium. It is a compound: magnesium joined to glycine, to citric acid, to oxygen. The compound weighs more than the magnesium inside it. The NIH Office of Dietary Supplements puts the consequence in one sentence: "The Supplement Facts panel on a dietary supplement label declares the amount of elemental magnesium in the product, not the weight of the entire magnesium-containing compound."

So a bottle can advertise 2,500 mg on the front and declare 275 mg in the panel, and both numbers can be correct. They are measuring different things.

How do you work out elemental magnesium from a label?

You divide the weight of magnesium in one molecule by the weight of the whole molecule, then multiply by the milligrams on the label. Magnesium weighs 24.305 on the atomic scale. Here is what that gives for the salts you see on shelves, calculated from the formula of each anhydrous compound.

Read the range again. The same 1,000 mg of powder carries 603 mg of magnesium as oxide and 83 mg as threonate. That is a sevenfold spread hiding behind identical front-of-bottle numbers.

Which forms of magnesium are absorbed best?

Forms that dissolve well in liquid tend to be absorbed better. The NIH Office of Dietary Supplements puts it this way: "In general, forms of magnesium that dissolve well in liquid have higher absorption than other forms, and the aspartate, citrate, lactate, and chloride forms of magnesium tend to have higher bioavailability than magnesium oxide and magnesium sulfate."

Glycinate is not part of that comparison, so it has no official place in the order. What the comparison shows is the pattern: the forms that dissolve well sit on the better-absorbed side, and oxide and sulfate sit on the other.

The Evening bottle uses magnesium glycinate, which is magnesium bound to the amino acid glycine.

Why does magnesium oxide look strongest on paper?

Oxide is 60.3% magnesium by weight, the highest figure in the table, and it is the cheapest form to manufacture. It is also one of the two forms the NIH groups with lower bioavailability, alongside sulfate. These facts describe different quantities: how much compound is in the capsule, how much of that compound is magnesium, and how much of that magnesium is absorbed. A high elemental percentage does not establish high absorption.

What do 2,500 mg and 275 mg mean on our Evening label?

Divide 275 by 2,500 and you get 11.0%. A pure anhydrous bisglycinate would work out at 14.1%, so 1,950 mg of it would carry 275 mg of magnesium. Our label needs 2,500 mg to get there.

The gap has a practical explanation. Commercial glycinate material is usually hydrated, and it is often buffered, which means water and other material add weight to the powder. A ratio below the anhydrous formula figure can therefore occur in a finished ingredient. The second number is the amount the Supplement Facts panel is required to declare, so it is the number you can compare across products.

If a bottle shows only the compound weight, you cannot do this division because you do not know what fraction to apply. The Evening bottle prints both numbers: three capsules, 2,500 mg of magnesium glycinate, 275 mg of elemental magnesium, and 30 servings. Its product claim is "Supports normal muscle and nerve function."

Does the form change how magnesium affects sleep?

The NIH comparison is about absorption, not sleep. A form that is absorbed better has not been shown to change sleep more than another form, and absorption alone cannot tell you that.

Light, screens, and five minutes of writing before lights out have been tested with polysomnography. You can review those results in the last twenty minutes before bed. In the Wake & Wind app, the wind-down timer provides the sequence. The capsules can serve as a routine cue, but they are not presented as a sleep mechanism.

How much magnesium is too much?

For adults, the tolerable upper intake level for supplemental magnesium is 350 mg per day. That limit applies to magnesium from supplements and medications, not to magnesium in food and drink. The recommended dietary allowance for adults runs from 310 to 420 mg per day depending on age and sex, and food is expected to supply most of it. Our Evening serving of 275 mg sits under the 350 mg supplemental limit, which is a fact about the number and not a recommendation for you.

Magnesium also interacts with medicines. The NIH lists oral bisphosphonates, tetracycline and quinolone antibiotics, and notes that diuretics and proton pump inhibitors can affect magnesium status. If any of those are in your cupboard, this is a question for the person who prescribed them.

Three things to check on any magnesium label

Is the elemental amount printed, or only the compound weight. Is the form named specifically, since "magnesium complex" tells you nothing you can divide. And does the percentage on the front refer to the thing you care about, which is the same trap we unpick on a mushroom label, where a percentage of polysaccharides gets read as a percentage of beta-glucans.

Three numbers, one division. That is the whole skill.

The Morning bottle is the other half of what we make, both bottles together are the set, and the reminder in the Wake & Wind app is there because a bottle nobody opens is a bottle nobody opens.