Magnesium

Magnesium: The Form on the Label Decides the Dose

Different magnesium compounds absorb very differently, and the cheapest one on the shelf is the one that absorbs worst.

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Compare elemental magnesium, not compound weight. Glycinate and citrate absorb well; oxide mostly does not.

Compound weight is not elemental weight

A capsule listing 500 mg of magnesium citrate does not provide 500 mg of magnesium. The figure that matters is elemental magnesium, which well-constructed panels state directly, often as 'magnesium (as magnesium citrate) 100 mg'.

Where a label gives only the compound weight, it is making itself hard to compare, and the comparison it is avoiding is usually unflattering.

Form changes the outcome more than dose does

Magnesium oxide is cheap and high in elemental magnesium by weight, which makes it look efficient on a panel. Its bioavailability is poor, and much of the dose passes through unabsorbed — which is also why it shows up in laxatives.

Glycinate is well absorbed and gentle on the gut, and is the common recommendation where tolerance matters. Citrate is well absorbed and inexpensive, with a mild laxative effect at higher doses that some people want and others do not. Malate and taurate are also well absorbed, at higher prices and with thinner comparative evidence.

The widely marketed sleep and recovery benefits are most plausible in people who are actually low in magnesium. Treating it as a sedative in someone already replete is asking a mineral to do a sleep-hygiene job.