You've probably heard magnesium mentioned. Sleep? Magnesium. Restless legs? Magnesium. A child who seems to run on a motor you can't find the off switch for? Also magnesium, apparently.
Magnesium is involved in hundreds of processes — muscle function, bone development, energy production, nervous system regulation² ³ ⁴. When intake is consistent, things run more smoothly. When it's not, things can feel a bit off.
Think of it as the stage manager of the body. Not the performer everyone notices, but the one making sure the lights work, the cues land, and the show doesn't fall apart mid-scene.
What magnesium actually does (the list is longer than you'd expect)
Magnesium is involved in:
• Normal muscle and nerve function⁴
• Bone and teeth development⁴
• Energy production from food³
• Immune system support
• Protein synthesis and cell formationᵇ ᶜ
It also plays a role in how the nervous system shifts between "go" and "slow" — which matters for everything from concentration to sleep².
Lower magnesium status has been observed alongside attention and mood challenges in some children, while adequate intake supports steadier nervous system functionᵈ.
The signs that don't announce themselves
Magnesium deficiency in children is usually mild — and easy to miss, because the signs often look like ordinary childhood.
Tiredness that doesn't quite add up. Persistent fatigue or muscle weakness can be linked to lower magnesium intakeᵃ ⁷. When an otherwise active child seems flat, it's worth considering the bigger picture.
Appetite or digestion changes. Magnesium plays a role in digestive function. Lower levels can sometimes show up as reduced appetite or mild tummy discomfortᶜ.
Muscle cramps or restless legs. Magnesium helps muscles contract and then release again — like a reset button between movements. Without enough, muscles can stay tense longer than they should, which is why cramps, "growing pains," or that restless can't-get-comfortable feeling often show upᶜ ⁴.
Mood changes. Magnesium is involved in nervous system regulation. Lower intake has been linked to increased irritability, anxiety, and emotional sensitivity in some children² ᵃ.
Trouble settling at night. Because magnesium supports the nervous system, lower levels may make it harder to fall asleep or stay asleep² ᵃ.
More severe deficiency is uncommon and involves symptoms that need medical attention. For most children, it's about patterns over time — not crisis pointsᶜ.
Finding it on the plate
Magnesium shows up in foods that don't always make it onto children's plates without negotiation:
Leafy greens Spinach, kale, chard — around 78mg per half cup of cooked spinach. (Yes, the foods currently being pushed to the side like they're radioactive.)ᶜ
Legumes Beans, lentils, chickpeas — around 60mg per half cup of cooked black beans. (Yes, beans. The ones that come with sound effects your 8-year-old finds hilarious.)ᶜ
Nuts and seeds Almonds, cashews, pumpkin seeds — around 80mg per ounce of almonds. Trail mix counts.ᶜ
Whole grains Oats, brown rice, quinoa, whole wheat bread. (Whether it counts if it's in a biscuit remains under investigation.)ᶜ
Fruits Bananas and avocados provide smaller but helpful amountsᵇ
Dairy Milk, yoghurt, and fortified alternatives contribute tooᶜ
Because magnesium tends to live in fibre-rich foods, diets that include vegetables, fruits, whole grains, and legumes usually support intake naturally — which is great in theory, and sometimes more complicated in practice.
Why magnesium can run low (without anyone noticing)
Modern eating patterns — including phases of narrow eating and more processed foods — can make magnesium intake less consistent than you'd expectᵃ.
It tends to dip during:
• Phases of rapid growth
• High activity or sport
• Sleep disruption
• Stretches where the same five foods rotate endlessly (pasta, bread, pasta, cheese, more pasta)
When families use supplements
For some families, magnesium through food alone doesn't quite stretch — especially during demanding phases.
Two commonly used forms:
• Magnesium citrate — well absorbed, often used in drinks or powders
• Magnesium glycinate — gentler on digestion, often chosen when calm or sleep support is the focus
And finally
Magnesium works alongside everything else — sleep, movement, food, routine, and the kind of support that doesn't fit on a label.
Leafy greens, nuts, seeds, wholegrains and legumes all provide it. A good supplement works alongside those — a steady backup for the days when pumpkin seed negotiations fail. This doesn't require perfection. It's about consistency over time, and paying attention to how your child feels as they grow, move, and (eventually, hopefully, ideally) sleep.
Leafy greens, nuts, seeds, wholegrains and legumes all provide it. A good supplement works alongside those — a steady backup for the days when pumpkin seed negotiations fail. This doesn't require perfection. It's about consistency over time, and paying attention to how your child feels as they grow, move, and (eventually, hopefully, ideally) sleep.
Supporting references
ᵃ USDA. Eye on Nutrition – Magnesium. ᵇ NIH Office of Dietary Supplements. Magnesium: Fact Sheet for Consumers. ᶜ Cleveland Clinic. Signs You May Have a Magnesium Deficiency. ᵈ Gröber U. et al. Magnesium in Prevention and Therapy. Nutrients. ᵉ USDA Agricultural Research Service. Magnesium: Nutrient Data. ᶠ Healthline. Types of Magnesium Supplements. ᵍ SickKids Hospital. Magnesium Supplement – Information for Parents. ʰ News-Medical Life Sciences. Magnesium cream and deficiency.
Authorised nutrition and health claims are presented separately in the page footer.
This is general information, not medical advice. If you have questions about your child's health, your GP or a registered healthcare professional is always the right place to start.
