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N
Moderate Evidence

Micronutrients

What evidence says about specific vitamins and minerals for ADHD and autism. When to test, when to supplement, and what to avoid.

Testing principles
Test before supplementing

Supplements only help if there's a deficiency. Random supplementation wastes money and can cause harm.

Consider risk factors

Restricted diets, picky eating, GI issues, certain medications increase deficiency risk.

GP can order basic tests

Ferritin, vitamin D, B12 are commonly available through NHS.

Retest after supplementation

Check levels have normalised and adjust accordingly.

Individual micronutrients

Iron
Testing:Strong EvidenceSupplementing:Moderate Evidence
Essential for dopamine production and oxygen transport to the brain.

Research says:

  • •Some studies show lower ferritin in children with ADHD
  • •Supplementation may help if deficient
  • •No benefit if iron levels are normal

Testing:

Ferritin (iron stores) - request if symptoms suggest deficiency or restricted diet.

Deficiency signs:

FatiguePale skinPoor concentrationPica (eating non-food items)

Food sources:

Red meatFortified cerealsBeansSpinachDried fruit

Note: Don't supplement without testing - excess iron is harmful.

Zinc
Testing:Moderate EvidenceSupplementing:Moderate Evidence
Involved in neurotransmitter function and brain development.

Research says:

  • •Some studies suggest lower zinc in ADHD
  • •May enhance methylphenidate effects if deficient
  • •Evidence is inconsistent overall

Testing:

Plasma or serum zinc - consider if restricted diet or GI issues.

Deficiency signs:

Poor appetiteSlow wound healingFrequent infectionsSkin problems

Food sources:

MeatShellfishCheeseNutsSeeds

Note: High doses can interfere with copper absorption. Test before supplementing.

Vitamin D
Testing:Strong EvidenceSupplementing:Moderate Evidence
Affects brain development, immune function, and mood regulation.

Research says:

  • •Many children are deficient, especially in UK/Ireland
  • •Some association with ADHD/autism in research
  • •Supplementation recommended for all UK children in winter

Testing:

25-hydroxyvitamin D - worth checking, especially in darker-skinned children or limited sun exposure.

Deficiency signs:

Often none until severeFatigueBone painFrequent illness

Food sources:

SunlightOily fishEgg yolksFortified foodsSupplements

Note: UK guidance: 400IU daily for all children October-March, year-round if limited sun.

Magnesium
Testing:Emerging EvidenceSupplementing:Emerging Evidence
Involved in hundreds of enzymatic reactions including neurotransmitter function.

Research says:

  • •Some studies suggest magnesium may help ADHD symptoms
  • •Often combined with B6 in studies
  • •Evidence is inconsistent and limited

Testing:

Serum magnesium - not always accurate as most magnesium is in cells.

Deficiency signs:

Muscle crampsPoor sleepAnxietyFatigue

Food sources:

NutsSeedsWhole grainsDark chocolateLeafy greens

Note: Generally safe at moderate doses. Some use for sleep support.

Omega-3 fatty acids
Testing:Not SupportedSupplementing:Mixed Evidence
Important for brain structure and function, anti-inflammatory effects.

Research says:

  • •NICE specifically advises against using for ADHD treatment
  • •Meta-analyses show small, inconsistent effects
  • •May have general health benefits but not ADHD-specific

Testing:

Not routinely tested.

Deficiency signs:

Dry skinDry eyesJoint stiffness

Food sources:

Oily fish (salmon, mackerel, sardines)WalnutsFlaxseedsChia seeds

Note: Food sources preferred. Supplements not recommended for ADHD specifically.

B vitamins
Testing:Moderate EvidenceSupplementing:Emerging Evidence
Various roles in energy metabolism and neurotransmitter synthesis.

Research says:

  • •B6 sometimes studied with magnesium
  • •B12 deficiency can mimic ADHD symptoms
  • •Limited evidence for supplementation if not deficient

Testing:

B12 - consider if vegan/vegetarian or GI issues.

Deficiency signs:

FatigueWeaknessCognitive difficultiesMood changes

Food sources:

MeatFishEggsDairyFortified foods

Note: B12 supplementation essential for vegans.

When to consider testing

Very restricted/picky eating
Vegetarian or vegan diet
GI conditions affecting absorption
Signs of specific deficiency
Before starting supplements
After prolonged supplementation (to check levels)

Supplement cautions

More is not better

Excess of some nutrients (iron, vitamin A, zinc) can be harmful.

Quality varies

Supplements are not as regulated as medications. Choose reputable brands.

Interactions exist

Some supplements interact with medications or each other.

ADHD supplements are often overpriced

Proprietary "ADHD blends" are expensive and no more effective than standard supplements.

Discuss with healthcare provider

Always discuss supplements with your doctor, especially if on medication.

The key insight

Supplements only help if there's a deficiency. Testing first ensures you're addressing a real problem. Food sources are generally preferred, and expensive "ADHD blends" are no better than standard supplements.

  • Test before supplementing - deficiencies need correcting, but supplements don't help normal levels
  • Vitamin D supplementation is recommended for all UK children in winter
  • NICE advises against omega-3 supplementation specifically for ADHD
  • Food sources are generally preferred over supplements where possible
  • Be sceptical of expensive "ADHD supplement blends"

Continue learning

Practical FrameworkGut-Brain AxisSpecial Diets