A glass of water and a magnesium supplement bottle on a wooden table

Which magnesium to choose

Oxide, citrate and bisglycinate are different salts. Compare them by the elemental magnesium on the label.

Read elemental magnesium, not the salt weight

A magnesium supplement is a salt or a chelate: magnesium joined to something else. The capsule weight is mostly that partner, not magnesium. Magnesium oxide, magnesium citrate and magnesium bisglycinate can all be honest products, and they are not the same number of milligrams of magnesium. The figure that matters is the elemental magnesium printed on the nutrition label, in milligrams per portion.

Magnesium oxide is a small molecule. About three fifths of its weight is magnesium, which is why a modest scoop can carry a high elemental dose. Citrate and bisglycinate are larger, so a gram of powder contains less elemental magnesium. That is chemistry, not a quality ranking. Compare two labels by the milligrams of magnesium, then by the dose you are willing to swallow.

Oxide, citrate and bisglycinate

Oxide is the concentrated form. It is common in multimineral tablets because the tablet stays small. Citrate is the salt of citric acid. Bisglycinate, also sold as glycinate, is magnesium bound to the amino acid glycine. Buffered powders sometimes mix bisglycinate with oxide, so the front of the pack can say bisglycinate while part of the magnesium still comes from oxide. The nutrition table is the check.

None of these names is a medical category. A shopper who wants less powder per milligram of magnesium will usually land on oxide. A shopper who wants the salt named on a particular formula reads the ingredient list for the exact compound, then checks that the elemental line still matches the dose they planned.

The 15% rule for authorised wording

In the EU nutrition table the nutrient reference value for magnesium is 375 mg a day. An authorised health claim may be used on a food or a food supplement only when the portion you are told to take in a day supplies at least 15% of that value. Fifteen percent of 375 mg is 56.25 mg of magnesium. A product under that line may still contain magnesium, but it may not carry the claim.

The condition is about the declared portion, not about a promise that a higher dose works better. Directive 2002/46/EC also requires the label to say that the stated recommended daily dose must not be exceeded. More tablets than the label are not a smarter use of the same product.

What the authorised claims actually say

Where the 15% condition is met, Regulation (EU) No 432/2012 allows wording of this kind: magnesium contributes to a reduction of tiredness and fatigue; to electrolyte balance; to normal energy-yielding metabolism; to normal functioning of the nervous system; to normal muscle function; to normal protein synthesis; to normal psychological function; to the maintenance of normal bones; to the maintenance of normal teeth; and it has a role in the process of cell division.

Each sentence describes a normal function of the nutrient. None of them is a statement about illness, cramp disorders, sleep disorders or mood disorders. Those uses are not authorised claims. A page that adds them is making a different, and unlawful, statement.

EFSA assessed the underlying nutrient claims in its opinions on magnesium, including the 2009 opinion in the EFSA Journal (7(9):1216). The Register of authorised claims, kept under Regulation (EC) No 1924/2006, is the list a label has to follow. A blog can explain the list. It cannot extend it.

Choosing among products we sell

On NovaLixir the mineral category is the practical place to compare magnesium salts side by side. Open the product, read the ingredient, and read the milligrams of magnesium per daily portion. If that portion is at least 56.25 mg, the authorised sentences above are the ones the nutrient can support. If the portion is lower, the bottle can still be a magnesium salt, but the claim does not belong on it.

Food supplements are concentrated sources of nutrients. They do not replace a varied diet or a healthy lifestyle, and they are not medicines. People who have been told by a doctor to limit minerals, including people with reduced kidney function, should follow that advice rather than a general shopping guide.

Questions

Is magnesium oxide a poor form because less of it is absorbed?

Absorption differs by salt and by dose, and a single percentage does not describe every person. The label fact you can compare in a shop is elemental magnesium in milligrams. Oxide simply packs more of that magnesium into less powder.

How much magnesium does a claim require?

At least 56.25 mg of magnesium in the daily portion named on the label. That is 15% of the EU nutrient reference value of 375 mg, which is the legal threshold for these claims on foods and food supplements.

Can magnesium be described as help for cramps or migraine?

No. Those are statements about disorders. The authorised wording is limited to normal functions such as muscle function, bones, and a reduction of tiredness and fatigue, and only when the portion meets the 15% rule.

What should I do with an unopened product I do not want?

Sealed food supplements are excluded from withdrawal once the seal is removed, because of health and hygiene. An unopened product can still be returned under the shop’s returns terms. An opened tub cannot.

Sources

Food supplements do not replace a varied diet and a healthy lifestyle.

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