Zinc supplements in ADHD
The National Survey of Children’s Heath showed that among individuals with ADHD, 66% are treated with medications. However, stimulants result in an “excellent” response rate in only 56% of children, according to the National Institute of Mental Health Multimodal Treatment Study of ADHD. Many parents and health professionals routinely consider supplements such as zinc to augment treatment with stimulants.
Conflicting study results
Animal and clinical trials implicate deficiencies of zinc—an essential cofactor in neurotransmitter, prostaglandin, and melatonin metabolism—in ADHD pathophysiology. However, many of the studies were conducted in the Middle East, a region where zinc deficiency is prevalent.
In a clinical trial, zinc versus placebo for 12 weeks was superior in reducing both hyperactive and impulsive symptoms, but not in reducing attention deficiency, in children from Turkey.1 A subsequent study found a significant decrease in parental scores for attention deficiency in addition to hyperactivity with zinc supplementation.2 Teacher scores reflected no change, however. In an American study, low serum zinc levels correlated with parent- and teacher-rated inattention but not hyperactivity.3 The inconsistent results may in part be due to dietary differences between the countries or differences in genetics, socioeconomics, ages, and numbers of children within studies.
Zinc as an adjunct to stimulants improved parental and teacher scores in children in an Iranian study, compared with methylphenidate alone,4 but an American study found scores from parents and teachers did not change significantly.5 Zinc supplements may have a stimulant-sparing effect by decreasing the needed dosage of d-amphetamine by 37% compared with placebo.5
What to tell parents
Additional research is needed to establish the role of zinc supplementation in ADHD. Supplements may improve ADHD symptoms in children who have zinc or marginal zinc deficiency; they may be used as adjunct therapy to stimulant medication. Parents should be counseled that nutrients such as zinc should come primarily from foods. A diet rich in zinc includes foods such as shellfish, poultry, red meat, beans, nuts, whole grains, fortified cereals, and dairy products. Counseling should also include recommended dietary allowances and upper intake levels for age of the child (see Table 1).
Table 1. Recommendations for zinc intake in children and adolescents
|Age||Recommended Dietary Allowance (mg)||Upper Tolerable Intake Levela (mg)|
a Maximum daily intake unlikely to cause adverse health effects.
b Adequate intake (evidence is insufficient for a Recommended Dietary Allowance).
Source: National Institutes of Health Office of Dietary Supplements. http://ods.od.nih.gov/factsheets/Zinc-HealthProfessional
Zinc as gluconate, sulfate, or acetate salts can supplement dietary intake. Adverse effects include epigastric pain, nausea, vomiting, loss of appetite, abdominal cramps, diarrhea, and headache, although most have been associated with excessive intake.
Zinc may interact with other minerals or medications. Large doses of iron can decrease zinc absorption. High zinc intakes may inhibit copper absorption, potentially causing copper deficiency and associated anemia. Patients ingesting large amounts of zinc should also receive copper supplementation.
- Bilici M, Yildirim F, Kandil S, et al. Double-blind, placebo-controlled study of zinc sulfate in the treatment of attention deficient hyperactivity disorder. Prog Neuropsychopharmacol Biol Psychiatry. 2004; 28:181–90.
- Uckardes Y, Ozmert EN, Unal F, et al. Effects of zinc supplementation on parent and teacher behaviour rating scores in low socioeconomic level Turkish primary school children. Acta Paediatr. 2009; 98:731–36.
- Arnold LE, Bozzolo H, Holloway J, et al. Serum zinc correlates with parent- and teacher-rated inattention in children with attention-deficit/hyperactivity disorder. J Child Adolesc Psychopharmacol. 2005; 15:628–36.
- Akhondzadeh S, Mohammadi MR, Khademi M. Zinc sulfate as an adjunct to methylphenidate for the treatment of attention deficient hyperactivity disorder in children: a double blind and randomized trial. BMC Psychiatry. 2004; 8:9.
- Arnold LE, DiSilvestro RA, Bozzolo D, et al. Zinc for attention-deficient/hyperactivity disorder: placebo-controlled double-blind pilot trial alone and combined with amphetamine. J Child Adolesc Psychopharmacol. 2011; 21:1–19.