by Joy Y. Kiddie, MSc, RD

While many people believe there is a link between diet and Attention Deficit Hyperactivity Disorder (ADHD) and some healthcare professionals recommend nutritional supplements for the disorder, there has been little scientific research describing the diet of ADHD children or measuring the actual level of these nutrients in the blood.

Children with ADHD may be at risk for several nutrient deficiencies due, in part to the demand on their attention to sit through a meal and get adequate calories and nutrients.  In addition, most medication prescribed for ADHD has the side effect of causing appetite suppression for a large part of the day.

A recent study by BetterByDesign's Dietitian Joy Y. Kiddie and Clinical Psychiatrist Dr. Margaret D. Weiss (co-authored by Dr. David D. Kitts, Dr. Ryna Levy-Milne and Michael B. Wasdell) called Nutritional Status of Children with Attention Deficit Hyperactivity Disorder: A Pilot Study published in the International Journal of Pediatrics indicates that ADHD children are taller and heavier than Canadian population norms based on standard CDC growth charts and taller but not heavier than what has been reported in previous ADHD samples. While it was thought that children with ADHD would eat more carbohydrate-based foods and more calories than non-ADHD children, this study found no significant difference between the ADHD children and Canadian population norms in terms of the total amount of calories they took in or proportion of calories derived from carbohydrate, protein or fat. In fact, children with ADHD did not eat more “junk food” than kids in the normal population; both groups ate ~28% of so-called Low-Nutrient Density (LND) foods.

This study demonstrated significantly lower dietary intakes of zinc and copper but not iron in ADHD children compared to population norms; this, despite the fact that children in this study were of higher socioeconomic status, and possibly had greater access to the more costly Meat and Alternate foods known to be high in these nutrients.

ADHD children aged 6–8 in this study had serum zinc that was significantly lower than population normal data with 26% having serum zinc values below the 2.5th percentile of the NHANES II cut-offs for zinc deficiency (=10.1?µmol/L/66?µg/dL).   The prevalence of zinc deficiency in ADHD children in this study was eight times greater than the normal prevalence of 3.3% reported for males and 3% for females.  Twenty percent of the ADHD children, aged 9–12 in this study, had serum zinc values below the 2.5th percentile cut-offs for zinc deficiency, a finding which is 20 times greater than the normal prevalence of zinc deficiency of 1% in females and slightly less than 1% in males.

The importance of these findings is that zinc, iron, and copper are essential cofactors in the production of dopamine and norepinephrine; two neurotransmitters critical in the aetiology of ADHD.

Further research is needed to determine if micronutrient deficiency is a cause, effect, or related to a third variable involved in ADHD.