One of us has a ten-year-old who trains football several times a week and comes home with aching legs. Magnesium is what she reaches for. One of us also takes magnesium bisglycinate for her own sleep, and wrote the paragraph further down saying the evidence there is thin. Both are true at once, and we'd rather show you that than pick whichever one sells better.
The short answer
- EFSA sets adequate intakes by age: 230 mg from 3 to 10, 250 to 300 mg from 10 to 18, and 300 to 350 mg for adults.
- The figure used on labels, the NRV, is 375 mg. That's higher than any of those recommendations, which is why the percentage on a label always looks modest.
- Form matters more with magnesium than with most nutrients, particularly for the gut.
- Our product covers roughly half a day's adequate intake. That's deliberate, and we explain why.
How much is recommended
For magnesium, EFSA doesn't set a required minimum in the way it does for some nutrients. It sets adequate intakes, based on what healthy populations across the EU actually consume.
| Age | Adequate intake (EFSA) |
|---|---|
| 1 to 3 | 170 mg |
| 3 to 10 | 230 mg |
| 10 to 18 | 300 mg (boys) · 250 mg (girls) |
| Adults | 350 mg (men) · 300 mg (women) |
Note that this is the first time in this series the figures genuinely change with age. With vitamin D the number is identical from age one onwards. With magnesium it's not, because the requirement tracks body mass.
Why the label percentage misleads
The reference value used in EU labelling is 375 mg. It's a single figure for every age, fixed in law, and it's higher than the adequate intake for any age group.
So a product supplying 100 mg of magnesium, a real and useful amount for a child, appears on the label as 26.7%. Sitting next to a vitamin at 500%, it looks trivial. It's not. It's being measured against a different ruler.
Rule of thumb: with magnesium, read the milligrams and ignore the percentage.
The forms, and why they matter here
Magnesium never appears alone in a supplement. It's always bound to something else, and that something else varies a great deal.
Magnesium oxide is the cheapest and most common. It carries a lot of magnesium by weight, which looks good on a label, but it's poorly absorbed and is well known for loosening the bowels.
Magnesium citrate is better absorbed and also has a recognised laxative effect at higher doses.
Magnesium bisglycinate is magnesium bound to the amino acid glycine. It's the most expensive of the three, it's well tolerated, and it's what we use.
This isn't a marketing distinction. If you've ever taken magnesium and spent the following morning regretting it, the form is the most likely explanation.
What magnesium actually does in the body
Magnesium isn't a single-purpose mineral, which is why it turns up in so many different conversations at once. Reviews of its physiology describe it as involved in several hundred enzymatic reactions.
Three threads run through it.
Energy. ATP is the molecule cells use to move energy around, and it's biologically active bound to magnesium: the physiological form is the magnesium-ATP complex rather than ATP alone. Magnesium contributes to normal energy-yielding metabolism and contributes to the reduction of tiredness and fatigue.
Nerve and muscle. Magnesium sits at the ion channels that let nerve and muscle cells fire and then relax again, which is why it appears in both stories. It contributes to the normal function of the nervous system and to normal muscle function.
Bone. Roughly half to two thirds of the body's magnesium is held in the skeleton. It contributes to the maintenance of normal bones.
On sleep and calm. These are the associations magnesium carries most often in conversation, and they're the ones where the research is weakest. The trials that exist tend to be small, short, and run in older adults who started with low magnesium status, and the results don't point the same way. Know that before choosing a product on that basis, from us or from anyone.
Where it's in food
Pulses, nuts, seeds, wholegrains, and dark green leafy vegetables. Magnesium sits at the centre of the chlorophyll molecule, which is why green leaves contain it.
A diet with pulses and nuts in it regularly gets close to the adequate intake with no supplement at all. Which is worth a thought before buying anything.
The honest part about our dose
Pocket Kids contains 100 mg of magnesium per daily dose. Teens 150 mg, Adults 200 mg.
Against the adequate intake, that's about 43% of the day for a child aged 3 to 10, and a little over half for an adult. It doesn't cover the day.
That's deliberate rather than modest. Magnesium is bulky: a full 300 mg dose as bisglycinate takes up considerable room, and a daily powder the whole household drinks has a practical limit on size and on taste. We chose an amount that complements food rather than trying to replace it.
If what you want is a full magnesium dose, a standalone magnesium product makes more sense than ours, and we say that knowing exactly what it means.
Sources
- EFSA, dietary reference values for magnesium, 2015
- EU Register of nutrition and health claims
- Regulation (EU) No 1169/2011, Annex XIII
Written by Lina and Stanislava, founders of MyDailyPocket. This is here to be useful, not to replace your GP or paediatrician. And no supplement is a substitute for a varied, balanced diet and a life with some sleep and daylight in it. Whatever you take, stay within the dose on the pack.
