No food or supplement cures ADHD, and diet has not been shown to cause it. Large reviews of studies find small or no effects for omega-3 and minerals, a small effect of food colourings in a minority of children, and only one strong result, for a very strict diet tested while parents knew what their child was eating. Almost all the studies are in children, and any blood test or supplement is a decision for a doctor.
- Omega-3: a small effect in the early meta-analyses, none on parent-rated symptoms in the 2023 Cochrane review.
- Artificial food colourings: a real but small effect, which may concern a minority of children.
- Elimination diet: 64% of children responded in a trial in the Netherlands and Belgium, where parents could not be blinded.
- Iron, zinc, magnesium: often lower levels on average, but few and fragile supplement trials.
- Sugar: double-blind trials find no effect on behaviour.
Why diet is hard to study in ADHD
ADHD symptoms are often measured with questionnaires filled in by parents. You can hide a supplement in a placebo capsule, but not a diet: the family knows what the child eats, and its expectations can colour its answers. By convention, an "effect size" of 0.2 is small, 0.5 medium and 0.8 large.
The European ADHD Guidelines Group measured this bias in 2013 (Sonuga-Barke and colleagues, 54 trials). When rated by the people closest to the treatment, every dietary intervention looked effective (0.21 to 0.48). With only probably blinded ratings, an effect remained for fatty acids (0.16) and for excluding food colourings (0.42, often in children selected for a food sensitivity), but no longer for elimination diets.
Omega-3: lower levels, a small or no benefit
Children and adolescents with ADHD have on average less DHA (effect size -0.76) and EPA (-0.38) in their blood, according to a 2018 meta-analysis (Chang and colleagues, Neuropsychopharmacology). Supplement trials are less clear. Bloch and Qawasmi (2011, 10 trials, 699 children) found a small effect (0.31), "modest" compared with ADHD medications according to the authors. But the 2023 Cochrane review, the most complete (37 trials, more than 2,374 participants), concludes with high certainty that these fatty acid supplements (omega-3 in most trials) do not change parent-rated symptoms, inattention or hyperactivity in the medium term. Only 3 small trials (191 participants) suggest, with low certainty, that more children improve on fatty acids. The UK's NICE guideline says not to offer fatty acid supplements to treat ADHD in children.
Artificial colourings: a small effect, in a minority of children
The Southampton study (McCann and colleagues, 2007) tested, double-blind, in 297 children aged 3 or 8-9 who were not selected for ADHD, drinks with or without a mix of artificial colourings and sodium benzoate. Effects on hyperactivity were small (0.12 to 0.32 depending on the analysis) and varied with the mix and the age. The European Food Safety Authority (EFSA) judged this evidence "limited", not enough to change the acceptable daily intakes. The European Union nevertheless requires, since July 2010, a statement on foods containing six colourings (E102, E104, E110, E122, E124, E129): they may have an adverse effect on activity and attention in children.
The meta-analysis by Nigg and colleagues (JAACAP, 2012), which covers children with ADHD or ADHD symptoms, finds an effect of colourings of 0.18 according to parents, 0.12 after correcting for possible publication bias, and, across all studies, no significant effect according to teachers and observers. The authors estimate that about 8% of children with ADHD may have symptoms related to synthetic food colourings, an estimate with a wide margin of error, they add. NICE says not to advise removing colourings and additives as a general treatment for ADHD in children.
The elimination diet: the strongest result, and the most debated
The INCA trial (Pelsser and colleagues, The Lancet, 2011) randomly assigned 100 children aged 4 to 8 with ADHD, in the Netherlands and Belgium. Half followed for 5 weeks a diet limited to a few foods (rice, meat, vegetables, pears, water, plus a few others), the other half received healthy eating advice. In the diet group, 32 of 50 children (64%) saw their symptoms fall by at least 40%.
The authors describe the limits themselves. Parents and teachers knew which child was on the diet; the assessing paediatrician did not, but based his ratings partly on what parents told him. Family expectations and the extra attention the child received cannot be ruled out. Next, under double-blind conditions, reintroducing foods brought symptoms back in 19 of the 30 responders, whatever their IgG antibody levels: the authors advise against diets based on IgG blood tests.
NICE notes that the long-term effectiveness and risks of such a diet in children are unknown, and that evidence of short-term benefit is limited. If a food seems to play a role, it advises a food diary, then a dietitian and the doctor for any exclusion. We come back to this trial in our article on ultra-processed foods and ADHD.
Iron, zinc, magnesium: lower levels, fragile trials
Iron. It is involved in making dopamine. Children with ADHD have on average lower ferritin, the body's iron store (Wang and colleagues, 2017, 10 studies: effect size -0.40). In a 2004 Paris study, it was low in 84% of children with ADHD, against 18% of controls. But the same team's controlled trial (Konofal and colleagues, 2008) included only 23 non-anaemic children with low ferritin, 5 of them on placebo: the ADHD rating scale and the clinical global impression improved on iron, but not the parent and teacher questionnaires. And too much iron is dangerous: very high doses can be fatal, particularly in children, the NHS warns.
Zinc. Meta-analyses of observational studies disagree on whether zinc is lower in ADHD. A large Turkish trial (Bilici and colleagues, 2004, 400 children, 12 weeks) found an effect on hyperactivity and impulsivity, not on attention; a full response was seen in 28.7% of children on zinc against 20% on placebo. The dose used was well above the safety limit set by EFSA for children of that age. A 2022 meta-analysis (6 trials, 489 children) finds a barely significant effect on the total score, no significant effect on hyperactivity or inattention, and rates the certainty of the evidence as moderate to very low.
Magnesium. Two 2019 meta-analyses find lower blood magnesium in children with ADHD. But the supplement study often quoted (1997) was open-label, with no placebo and no blinding. For iron, zinc and magnesium, a 2017 review (Lange and colleagues) concludes that convincing evidence is lacking.
Vitamin D follows the same pattern: lower levels on average, few trials, covered in Vitamin D and ADHD. For all these nutrients, a low level may be a consequence rather than a cause, for example in a child who eats very selectively. And only a blood test ordered by a doctor shows a deficiency: a DNA test cannot, as we explain in our article on "nutrition" DNA tests.
Sugar: a stubborn myth
A meta-analysis of 23 double-blind studies (Wolraich and colleagues, JAMA, 1995) finds no effect of sugar on children's behaviour or cognition, although a small effect in some children cannot be ruled out. Expectations, on the other hand, matter. In a 1994 experiment, 35 boys aged 5 to 7 said to be "sugar-sensitive" all received a placebo; mothers who had been told their son had taken sugar rated him as significantly more hyperactive.
Diet as a whole: an association, not proof
In Spain, among 120 children and adolescents, low adherence to a Mediterranean diet was associated with an ADHD diagnosis (Ríos-Hernández and colleagues, Pediatrics, 2017). A meta-analysis of 14 studies (Del-Ponte and colleagues, 2019) finds lower odds of ADHD with a "healthy" diet (odds ratio 0.65) and higher odds with a diet rich in refined sugar and saturated fat (1.41). The authors rate this evidence as weak. These are associations, and the link may run the other way. The same goes for mood, as shown in Food and Mood: What Is Actually Proven in Humans.
What you can take away
- A varied, balanced diet helps everyone: it is NICE's first recommendation on the subject, along with physical activity.
- No supplement or restrictive diet without medical advice, especially for a child. Testing a nutrient level and any supplement are decided with the doctor: some doses used in trials exceed EFSA safety limits for children.
- If a food seems to play a role, write down meals and behaviour in a diary and show it to the doctor.
- Diet does not replace an assessment or a treatment. Do not start, stop or change any treatment without talking to your doctor.
To prepare for an appointment, you can fill in our ASRS self-assessment questionnaire for adults or the questionnaire for parents of a child aged 6 to 17. The result is not a diagnosis.
Frequently asked questions
Does omega-3 improve ADHD?
Early meta-analyses found a small effect; the 2023 Cochrane review (37 trials) finds none on parent-rated symptoms. Talk to your doctor before taking any supplement.
Should my child's iron or vitamin D be tested?
That is for the doctor to decide; a confirmed deficiency is treated under medical supervision. IgG tests do not tell you which foods to remove, and a DNA test does not measure a lack of nutrients.
Can an elimination diet replace treatment?
No. The INCA trial suggests that some children react to certain foods, but parents were not blinded in its first phase and there are no long-term data. A diet this strict should only be considered with a doctor and a dietitian.
References: Sonuga-Barke EJ et al. (2013). Nonpharmacological interventions for ADHD: systematic review and meta-analyses of randomized controlled trials of dietary and psychological treatments. American Journal of Psychiatry 170(3):275-289, doi:10.1176/appi.ajp.2012.12070991 (meta-analyses, 54 trials) | Chang JP et al. (2018). Omega-3 polyunsaturated fatty acids in youths with attention deficit hyperactivity disorder: a systematic review and meta-analysis of clinical trials and biological studies. Neuropsychopharmacology 43(3):534-545, doi:10.1038/npp.2017.160 (7 trials, 534 youths; case-control studies of blood levels) | Bloch MH, Qawasmi A (2011). Omega-3 fatty acid supplementation for the treatment of children with attention-deficit/hyperactivity disorder symptomatology: systematic review and meta-analysis. J Am Acad Child Adolesc Psychiatry 50(10):991-1000, doi:10.1016/j.jaac.2011.06.008 (10 trials, 699 children) | Gillies D, Leach MJ, Perez Algorta G (2023). Polyunsaturated fatty acids (PUFA) for attention deficit hyperactivity disorder (ADHD) in children and adolescents. Cochrane Database of Systematic Reviews 4:CD007986, doi:10.1002/14651858.CD007986.pub3 (systematic review, 37 trials) | McCann D et al. (2007). Food additives and hyperactive behaviour in 3-year-old and 8/9-year-old children in the community: a randomised, double-blinded, placebo-controlled trial. The Lancet 370(9598):1560-1567, doi:10.1016/S0140-6736(07)61306-3 (crossover trial, 297 children) | EFSA AFC Panel (2008). Opinion on the results of the study by McCann et al. (2007) on the effect of some mixtures of synthetic colours and sodium benzoate on children's behaviour. EFSA Journal 660, doi:10.2903/j.efsa.2008.660; conclusions in the minutes of the plenary meeting of 6-7 March 2008 | Regulation (EC) No 1333/2008 on food additives, Articles 24 and 35, Annex V | Nigg JT et al. (2012). Meta-analysis of attention-deficit/hyperactivity disorder or attention-deficit/hyperactivity disorder symptoms, restriction diet, and synthetic food color additives. J Am Acad Child Adolesc Psychiatry 51(1):86-97.e8, doi:10.1016/j.jaac.2011.10.015 (meta-analysis, 24 publications on colourings, 10 on diets) | Pelsser LM et al. (2011). Effects of a restricted elimination diet on the behaviour of children with attention-deficit hyperactivity disorder (INCA study): a randomised controlled trial. The Lancet 377(9764):494-503, doi:10.1016/S0140-6736(10)62227-1 (randomised trial, 100 children) | NICE (2018, updated 2019). Attention deficit hyperactivity disorder: diagnosis and management (NG87), recommendations 1.6.1 to 1.6.5 | Wang Y et al. (2017). Iron status in attention-deficit/hyperactivity disorder: a systematic review and meta-analysis. PLoS One 12(1):e0169145, doi:10.1371/journal.pone.0169145 (10 studies, 2,191 participants) | Konofal E et al. (2004). Iron deficiency in children with attention-deficit/hyperactivity disorder. Arch Pediatr Adolesc Med 158(12):1113-1115, doi:10.1001/archpedi.158.12.1113 (53 children, 27 controls) | Konofal E et al. (2008). Effects of iron supplementation on attention deficit hyperactivity disorder in children. Pediatric Neurology 38(1):20-26, doi:10.1016/j.pediatrneurol.2007.08.014 (randomised trial, 23 children) | NHS. Iron (vitamins and minerals) | Ghoreishy SM et al. (2021). Zinc status in attention-deficit/hyperactivity disorder: a systematic review and meta-analysis of observational studies. Scientific Reports 11:14612, doi:10.1038/s41598-021-94124-5 (22 studies) | Wang W et al. (2026). Essential trace elements zinc, iron, copper and attention-deficit/hyperactivity disorder in children and adolescents: a systematic review and meta-analysis of case-control studies. Nutrients 18(11):1797, doi:10.3390/nu18111797 (46 studies) | Bilici M et al. (2004). Double-blind, placebo-controlled study of zinc sulfate in the treatment of attention deficit hyperactivity disorder. Prog Neuropsychopharmacol Biol Psychiatry 28(1):181-190, doi:10.1016/j.pnpbp.2003.09.034 (randomised trial, 400 children) | Talebi S et al. (2022). The effect of zinc supplementation in children with attention deficit hyperactivity disorder: a systematic review and dose-response meta-analysis of randomized clinical trials. Crit Rev Food Sci Nutr 62(32):9093-9102, doi:10.1080/10408398.2021.1940833 (6 trials, 489 children) | EFSA. Overview on Tolerable Upper Intake Levels, version 11, August 2025 | Huang YH et al. (2019). Significantly lower serum and hair magnesium levels in children with attention deficit hyperactivity disorder than controls: a systematic review and meta-analysis. Prog Neuropsychopharmacol Biol Psychiatry 90:134-141, doi:10.1016/j.pnpbp.2018.11.012 (12 studies) | Effatpanah M et al. (2019). Magnesium status and attention deficit hyperactivity disorder (ADHD): a meta-analysis. Psychiatry Research 274:228-234, doi:10.1016/j.psychres.2019.02.043 (7 studies) | Starobrat-Hermelin B, Kozielec T (1997). The effects of magnesium physiological supplementation on hyperactivity in children with attention deficit hyperactivity disorder (ADHD). Positive response to magnesium oral loading test. Magnesium Research 10(2):149-156 (open study, 50 treated and 25 untreated children) | Lange KW et al. (2017). The role of nutritional supplements in the treatment of ADHD: what the evidence says. Current Psychiatry Reports 19(2):8, doi:10.1007/s11920-017-0762-1 (review) | Khoshbakht Y, Bidaki R, Salehi-Abargouei A (2018). Vitamin D status and attention deficit hyperactivity disorder: a systematic review and meta-analysis of observational studies. Advances in Nutrition 9(1):9-20, doi:10.1093/advances/nmx002 (13 observational studies) | Wolraich ML, Wilson DB, White JW (1995). The effect of sugar on behavior or cognition in children: a meta-analysis. JAMA 274(20):1617-1621, doi:10.1001/jama.1995.03530200053037 (23 studies) | Hoover DW, Milich R (1994). Effects of sugar ingestion expectancies on mother-child interactions. J Abnorm Child Psychol 22(4):501-515, doi:10.1007/BF02168088 (35 boys) | Ríos-Hernández A et al. (2017). The Mediterranean diet and ADHD in children and adolescents. Pediatrics 139(2):e20162027, doi:10.1542/peds.2016-2027 (case-control, 120 young people) | Del-Ponte B et al. (2019). Dietary patterns and attention deficit/hyperactivity disorder (ADHD): a systematic review and meta-analysis. J Affect Disord 252:160-173, doi:10.1016/j.jad.2019.04.061 (14 observational studies)