Is there any benefit to magnesium oxide?
Answer
Two: it is the cheapest form and it carries the most magnesium per gram. Against that it absorbs poorly, and the unabsorbed portion produces the laxative effect it is known for.
Key takeaways
- What is it good at?
- Cost and magnesium density. About 60 percent magnesium by weight, and the cheapest raw material on the shelf.
- What is the trade off?
- Poor absorption, so a large elemental figure does not translate into a large amount reaching you.
- Is it ever the right choice?
- It is used medically as a laxative, which tells you most of what you need to know about daily use.
What it genuinely offers
Magnesium oxide carries about 60 percent magnesium by weight, more than any other common form, because oxygen is a small partner. So a modest amount of compound produces a large elemental figure, and the raw material is the cheapest available.
On a label that combination looks excellent. A 500mg oxide capsule can print roughly 300mg of elemental magnesium, which is the same figure Futuro Labs Magnesium Glycinate reaches from 1500mg of bisglycinate.
Why it still is not the choice for daily use
Absorption. Oxide is poorly absorbed, so the elemental figure on the label overstates what reaches the player, and the portion that is not absorbed stays in the gut and draws water into it.
That is the mechanism behind the laxative effect, and it is why magnesium oxide is used medically for exactly that purpose. UK guidance sets 400mg a day for supplemental magnesium because of that effect rather than because of any toxicity.
Where it still turns up
In budget products where a high elemental figure at a low price is the whole selling point, and inside buffered magnesium bisglycinate, which is bisglycinate blended with oxide to raise elemental content per gram cheaply.
The tell for the second is an elemental figure well above 20 percent of the stated compound weight, because bisglycinate alone is about a fifth magnesium. Futuro Labs Magnesium Glycinate uses bisglycinate alone at 300mg elemental for 22p a day, which is 7.4p per 100mg.
The full version
- What is the downside of magnesium oxide?The trade off in full, and where oxide hides in blends.
- How to compare magnesium forms without the marketingThe three axes that actually separate the forms.
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
Is magnesium oxide any good?
Cheap and magnesium dense, and poorly absorbed with the worst tolerability at a full serving.
Why does it print a big elemental figure?
It is about 60 percent magnesium by weight, so a small amount of compound goes a long way on paper.
Where does it hide?
In buffered bisglycinate, which blends the two to raise elemental content cheaply.