The current study reports that ADHD children in this sample 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 [41
]. Our finding is consistent with previous reports which indicate that ADHD children in other local samples may be larger than non-ADHD children of the same age and gender [43
]. It is unclear why ADHD children in these samples do not appear to follow standardized growth curves.
Independent sample t-tests showed no significant difference in height-for-age (t (38) = 0.11, P = .91) between drug-treated subjects and drug-naïve subjects indicating that the medication status of the subjects examined in this study was not a factor. This may be because of the young age and low drug exposure of the children in the study.
This study found no significant difference between the ADHD children in this sample and population norms in mean energy intake, calories or proportion of calories derived from protein, fat, or carbohydrate as compared with data from the recent Canadian Community Health Study [20
]. ADHD children in this study consumed the same percentage (28%) of Low-Nutrient Density (LND) foods as reported in age-matched population normal data [33
] which is important given that LND foods are known to displace nutrient-rich foods in the diet [33
]. Maternal concerns expressed during the study that their ADHD children are “junk food junkies” do not seem to be empirically justified in this sample, in comparison to children of the same age and gender from the population.
This is the first study to demonstrate significantly lower dietary intakes of micronutrients in ADHD children compared to population norms [44
]. Despite the fact that children in this study were biased towards subjects of higher socioeconomic status, possibly contributing to subjects having greater access to the more costly Meat and Alternate foods known to be high in zinc, and copper, it is unknown why subjects consumed less Meat and Alternates than the norm.
This study is limited by the relatively small sample size and by lack of a specific normal control group. In addition, the study did not control for vitamin and mineral supplementation. That being said, all subjects had blood samples drawn in the morning in a nonfasted state and all analysis were performed at the same laboratory at BC Children's Hospital as the lab normal data with which the results were compared.
This study adds to the growing literature demonstrating low serum zinc in ADHD children [8
] and reports for the first time low dietary intake of zinc and copper and low serum copper status in a sample of ADHD children.
Further research is needed to help identify the etiology, impact, and possible therapeutic implications of low micronutrient status in ADHD, given the essential nature of these micronutrients in the production of the neurotransmitters involved in ADHD.