Last updated: June 2026
Magnesium is involved in over 300 biochemical processes in the body — from energy production and bone development to mood regulation and sleep. And magnesium deficiency in children is more common than many parents realise. Here’s everything you need to know.
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Symptoms of low magnesium in children
Magnesium deficiency symptoms in children can be split into behavioural and physical categories. Importantly, these symptoms can also point to other conditions — a GP should always be consulted rather than self-diagnosing a deficiency.
Behavioural signs
- Moodiness and irritability
- Hyperactivity and difficulty concentrating
- Insomnia and trouble staying asleep
- Anxiety and excessive worrying
Physical signs
- Fatigue and low energy
- Nausea and stomach cramps
- Teeth grinding (bruxism)
- Eye twitching
- Noise sensitivity
- Growing pains
- Constipation
- Poor appetite
Why do children need magnesium?
Magnesium is essential for over 300 biochemical reactions — including muscle and nerve function, blood sugar regulation, bone development and DNA synthesis. In children specifically, it plays a critical role in:
- Mood regulation and emotional balance
- Sleep quality and duration
- Cognitive function and concentration
- Healthy bone growth and development
Magnesium and ADHD
A small study published in Science Daily found magnesium deficiency in 72% of children with ADHD. Of those given magnesium supplementation, children showed statistically significant improvements in inattention (77.7%) and hyperactivity (88.9%). Children with ADHD are more likely to have picky eating habits that make dietary magnesium intake inadequate, which may explain the overlap.
Magnesium and autism
Research dating to 1978 has linked autism spectrum disorder (ASD) with magnesium deficiency. Further studies found magnesium has potential to prevent developmental delay. Children with ASD, like those with ADHD, often have more restricted diets and food sensitivities that increase the risk of deficiency.
Read more: Magnesium for sleep | Types of magnesium
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Take the free health quiz →How much magnesium do kids need?
UK and international guidelines for daily magnesium intake in children:
- Ages 1–3: around 80 mg/day from food; supplement upper limit 65 mg/day
- Ages 4–8: around 130 mg/day from food; supplement upper limit 110 mg/day
- Ages 9–13: around 240 mg/day from food; supplement upper limit 350 mg/day (same as adults)
Getting magnesium from food carries no upper limit concern. Supplement doses above the listed limits can cause side effects including abdominal pain and diarrhoea in some children. Always consult a GP before giving any supplement to a child.
How to get more magnesium into children’s diets
The best approach is always dietary first. Magnesium-rich foods include:
- Leafy greens (spinach, kale, broccoli)
- Nuts and seeds (almonds, pumpkin seeds)
- Legumes (black beans, lentils)
- Whole grains (oats, brown rice)
- Low-fat dairy (milk, yoghurt)
For picky eaters: hide spinach in smoothies with banana and berries, use quality almond butter in snacks, or stir finely chopped vegetables into pasta sauces. Small consistent additions build magnesium intake without battles.
Choosing magnesium supplements for kids
If dietary improvement isn’t sufficient and a GP supports supplementation, key considerations:
- Choose highly bioavailable forms — magnesium glycinate (gentle, well-absorbed), magnesium citrate (most-studied in children), or magnesium L-threonate (crosses the blood-brain barrier — relevant for ADHD/ASD neurological support)
- Match form to reason — for mood and cognitive support, L-threonate is the only form that meaningfully raises brain magnesium. For general deficiency, citrate or glycinate are good choices.
- Choose high quality, organic — free from heavy metals, toxins and unnecessary fillers. Look for brands with published lab reports.
- Start low — begin at the lower end of the age-appropriate supplement range and monitor for side effects
Read more: Magnesium L-threonate guide
Frequently asked questions
Should I give my child magnesium?
If you suspect deficiency, try improving dietary intake first. Supplementation can help some children — but always speak to a GP before giving any supplement to a child.
What age can children take magnesium?
Many guidelines include dosages from age 1+. For young children, always seek GP guidance before starting any supplement.
Can magnesium help children with ADHD?
Research suggests a link between ADHD and magnesium deficiency. Small studies found improvements in inattention and hyperactivity with supplementation. This should always be done under medical supervision.
Which form of magnesium is best for children?
Magnesium citrate is the most-studied form in children. Magnesium glycinate is gentle and well-tolerated. Magnesium L-threonate is relevant for neurological support in ADHD or ASD. Always discuss with your GP.
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Take the free health quiz →Final thoughts on magnesium for kids
Magnesium deficiency in children is common and can manifest as a wide range of behavioural and physical symptoms that are easily missed or attributed to other causes. The best approach is always dietary first — building magnesium into meals consistently. If supplementation is needed, work with a GP to choose the right form and dose, and always start conservatively. For children with ADHD or ASD, magnesium may be particularly worth discussing with their medical team.
