What are the signs of too much magnesium?
Answer
Loose stools and stomach discomfort, which appear well before anything else and are the reason the 400mg supplemental guidance level exists. Serious effects are rare with normal kidney function.
Key takeaways
- What is the first sign?
- Loose stools or diarrhoea, and stomach discomfort. Both are dose dependent and worst with oxide.
- At what intake?
- UK guidance sets 400mg a day from supplements, and the effect appears around and above that.
- When is it medical?
- Anyone with reduced kidney function should not supplement without medical advice, because magnesium is cleared by the kidneys.
What actually happens first
Loose stools and stomach discomfort. Both are dose dependent, both appear well before anything else, and both resolve on reducing the dose or changing form.
The mechanism is straightforward: unabsorbed magnesium stays in the gut and draws water into it. That is also why magnesium oxide, which is poorly absorbed, produces it most readily and is used medically as a laxative.
Where the guidance level comes from
UK guidance sets 400mg a day for supplemental magnesium specifically, and the figure is set on that laxative effect rather than on toxicity in healthy adults.
Futuro Labs Magnesium Glycinate provides 300mg elemental in a two capsule serving at 22p a day, which leaves 100mg of headroom. Most people who approach the ceiling do it through overlap between a multivitamin, a ZMA product and a dedicated supplement rather than from one.
When it is genuinely medical
Magnesium is cleared by the kidneys, so anyone with reduced kidney function should not take supplemental magnesium without medical advice. That is the situation where the guidance level understates the caution needed.
Serious excess is rare from oral supplements in healthy adults and is a recognised clinical problem in specific circumstances. Anything beyond loose stools, and anything persisting after stopping, is a GP question rather than a dose adjustment.
The full version
- Magnesium side effects for rugby playersWhat is recognised, what is not, and the supplemental ceiling.
- Is 500mg of magnesium too much?Whether the figure on your label is elemental or a compound weight.
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
What are the signs of too much?
Loose stools and stomach discomfort, which appear well before anything else.
At what intake?
Around and above the 400mg supplemental guidance level, and sooner with oxide.
Who should not supplement?
Anyone with reduced kidney function, without medical advice.