Omega-3s, zinc, iron, magnesium, and vitamin D have the most evidence for ADHD. Herbal supplements are largely unproven. Here is what the research shows — and what to test before you supplement.
For educational purposes only — not medical advice. How we evaluate evidence →
Natural, evidence-informed approaches to ADHD across all ages.
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Dr. A. Ferreira, MDGeneral practitioner with integrative medicine training. Reviewed for factual accuracy. Supplements for ADHD should be used as adjuncts to — not replacements for — evidence-based treatment. Test for deficiencies before supplementing. Always consult your healthcare provider.
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This article is for educational purposes only and does not constitute medical advice. Always consult a qualified healthcare professional before making health decisions. Our editorial standards →
The supplement market for ADHD is vast and largely unregulated — with hundreds of products making claims that far exceed the available evidence. However, a handful of supplements have accumulated meaningful research suggesting genuine benefit, particularly in individuals with documented deficiencies. This article reviews the evidence for the most studied supplements, explains the mechanisms, and provides practical guidance on testing and dosing.
Omega-3 Fatty Acids: The Most Evidence-Supported Supplement. As detailed in the ADHD and Diet article, omega-3 supplementation has the strongest evidence base of any supplement for ADHD. A 2018 meta-analysis of 16 RCTs found significant improvements in attention and hyperactivity. The effect size is approximately one-third of stimulant medication — meaningful but not transformative as a standalone intervention. Key considerations: use a high-EPA formula (EPA:DHA ratio of at least 2:1); dose of 1–2g combined EPA+DHA daily; algae-based omega-3 is suitable for vegetarians and avoids heavy metal concerns; effects may take 3–6 months to become apparent; most beneficial in those with low baseline omega-3 levels (a blood test can confirm).
Iron: Test Before You Supplement. Iron is a cofactor for the synthesis of dopamine and norepinephrine — the neurotransmitters most implicated in ADHD. Ferritin (the storage form of iron) below 30 ng/mL is associated with more severe ADHD symptoms, and multiple studies have found that iron supplementation in iron-deficient children with ADHD produces significant symptom improvement. A 2004 study found that iron supplementation (80 mg/day for 12 weeks) in iron-deficient children with ADHD produced improvements in ADHD symptoms comparable to those seen with stimulant medication. Critical caveat: iron supplementation in individuals with normal iron levels is not beneficial and can cause harm (iron overload, gastrointestinal side effects, interference with zinc absorption). Always test ferritin before supplementing with iron.
Zinc: Modest but Consistent Evidence. Zinc is a cofactor for dopamine metabolism and modulates the dopamine transporter — the primary target of stimulant medications. Children with ADHD consistently show lower serum zinc levels than neurotypical controls. A 2004 Turkish RCT found that zinc supplementation (55 mg/day for 12 weeks) significantly reduced hyperactivity and impulsivity in children with ADHD. A 2011 study found that zinc supplementation enhanced the effects of methylphenidate (Ritalin), allowing a lower effective dose. Effect sizes are modest — zinc is unlikely to be sufficient as a standalone treatment but may be a useful adjunct, particularly in zinc-deficient individuals. Dose: 15–30 mg elemental zinc daily (as zinc gluconate or zinc picolinate); test serum zinc before supplementing; high-dose zinc supplementation can deplete copper and should not be taken long-term without monitoring.
Magnesium: Hyperactivity and Sleep. Magnesium deficiency is associated with hyperactivity, impulsivity, and sleep disturbance — all of which are common in ADHD. A 2017 systematic review found that magnesium supplementation significantly reduced hyperactivity in children with ADHD and low magnesium levels. Magnesium also improves sleep quality, which is particularly relevant given that 50–70% of children with ADHD have sleep problems that worsen daytime symptoms. Magnesium glycinate and magnesium L-threonate are the best-absorbed forms with the fewest gastrointestinal side effects. Dose: 100–400 mg elemental magnesium daily (age and weight-dependent for children); best taken in the evening to support sleep.
Multiple studies have found that children and adults with ADHD have significantly lower vitamin D levels than neurotypical controls. A 2018 RCT found that vitamin D supplementation (2000 IU/day for 8 weeks) significantly improved inattention, hyperactivity, oppositional behaviour, and anxiety in children with ADHD and vitamin D deficiency. The mechanism likely involves vitamin D's role in dopamine synthesis and neuroinflammation regulation. Given the high prevalence of vitamin D deficiency (over 40% of the US population), testing and supplementing to optimal levels (75–125 nmol/L) is a low-risk, potentially high-benefit intervention.
Pycnogenol (French Maritime Pine Bark Extract): Promising but Preliminary. Pycnogenol is a standardised extract from French maritime pine bark, rich in procyanidins and other polyphenols. A 2006 RCT found that pycnogenol supplementation (1 mg/kg/day for 4 weeks) significantly reduced hyperactivity and improved attention and motor coordination in children with ADHD. A 2010 study found that pycnogenol normalised urinary catecholamine levels (dopamine and norepinephrine metabolites) in children with ADHD. The evidence is preliminary but mechanistically plausible — pycnogenol has antioxidant and anti-inflammatory effects that may reduce oxidative stress in dopaminergic neurons. Dose: 1 mg/kg/day (typically 40–100 mg for children).
Supplements with Insufficient Evidence. Ginkgo biloba: one small RCT showed modest benefit; evidence insufficient to recommend. Bacopa monnieri: some evidence for memory and attention in healthy adults; limited ADHD-specific research. Phosphatidylserine: some evidence for cognitive function; one small RCT showed benefit in ADHD but needs replication. Melatonin: not a treatment for ADHD symptoms per se, but strong evidence for improving sleep onset in children with ADHD and sleep problems — which indirectly improves daytime symptoms. Dose: 0.5–3 mg, 30–60 minutes before bedtime.
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