Which magnesium has the highest elemental content?
Answer
Magnesium oxide, at about 60 percent magnesium by weight. It is also the least well absorbed, so the highest figure on a label does not mean the most magnesium reaching you.
Key takeaways
- Which is highest?
- Oxide, at about 60 percent magnesium by weight, well ahead of every other common form.
- Does that make it best?
- No. It is poorly absorbed, and the unabsorbed portion produces the laxative effect it is known for.
- What is a better comparison?
- Cost per 100mg of elemental magnesium alongside how tolerable the form is at a full serving.
The ranking by weight
Oxide is about 60 percent magnesium by weight. Bisglycinate is about 20 percent, citrate about 16, malate about 15, lactate about 12, taurate about 9 and threonate about 8.
That ordering is why a 500mg oxide capsule can print roughly 300mg of elemental magnesium while it takes 1500mg of bisglycinate to reach the same figure. Oxygen is a small partner and glycine is a large one.
Why the highest is not the best
Absorption. Oxide is poorly absorbed, so a large elemental figure on a label overstates what reaches the player, and the portion that stays in the gut draws water into it, which is why the compound is used medically as a laxative.
Futuro Labs Magnesium Glycinate uses bisglycinate at 300mg elemental per two capsule serving for 22p a day, which is 7.4p per 100mg. That is the tolerability route rather than the density one.
The comparison worth running instead
Cost per 100mg of elemental magnesium, which normalises for the fact that a taurate product needs three times the compound weight of a bisglycinate one for the same magnesium.
Then tolerability at a full daily serving, because a product abandoned in November delivers nothing across a season. Those two settle the form question more usefully than any density ranking does.
The full version
- How to work out the elemental magnesium in any supplementThe conversion for every common form, with worked examples.
- What is the downside of magnesium oxide?Why the densest form is the weakest daily choice.
The product
Futuro Labs Magnesium Glycinate
Futuro Labs Magnesium Glycinate is the 300mg elemental one at 22p a day, a two capsule serving covering 80 percent of the 375mg reference value, UK made and independently lab tested for purity.
- 300mg elemental magnesium, 80% NRV
- Bisglycinate, best tolerated common form
- UK made to GMP, lab tested for purity
- Not batch certified for sport
Sharper Rugby is published by Futuro Labs. If you buy through this link Futuro Labs earns from the sale. Prices are set by Amazon.
Questions players ask
Which form has the most magnesium?
Oxide, at about 60 percent by weight.
Is that the best one to buy?
No. It is poorly absorbed and the least well tolerated at a full serving.
What should I compare instead?
Cost per 100mg of elemental magnesium, alongside tolerability across a season.