Researchers from Erasmus University Medical Center in Rotterdam assessed the diets of nearly 3,700 children aged 6, 8 and 10, with ADHD, from Rotterdam.
The findings, published in The Journal of Nutrition, concluded that while kids with ADHD are more likely to have unhealthy diets, their poor diets weren't at the root of their symptoms.
Study author Trudy Voortman, assistant professor of nutritional epidemiology, said: "In contrast to what may be expected, we observed that a poor diet does not predict the level of ADHD symptoms in children, either diagnosed or not. So, based on our study, dietary changes may not prevent or reduce ADHD symptoms."
Parents completed the Child Behaviour Checklist when children were 6 and 10 years of age, while dietary intake was assessed at the age of 8, with a validated food-frequency questionnaire.
Voortman said that children with ADHD had higher than recommended amounts of sugar-sweetened beverages and processed meats. She said their diets tended to be lacking in legumes, vegetables and nuts.
But the researchers wanted to know if the quality of a child's overall diet might make a difference in their symptoms.
The researchers suggested the reasons for the poor dietary choices of those with ADHD may have something to do with symptoms, such as restlessness and poor self-regulation.
"This may translate into impulsive eating of highly palatable foods or having no patience to eat vegetables, which are less rewarding than high-calorie foods," Voortman said.
It's also possible that parents may try to soothe difficult behaviour by offering kids the meals and snacks they prefer instead of healthier choices, she noted.
Dr. Andrew Adesman, chief of developmental and behavioural paediatrics at Cohen Children's Medical Center in New Hyde Park, N.Y., reviewed the study. He felt it wasn't yet clear if the ADHD symptoms led to the unhealthy diet.
"Although it is possible that underlying ADHD symptoms may be responsible for dietary differences, this remains an open question," said Adesman, who had no part in the research.
He said the study does suggest that diet isn't likely "central to the development of ADHD or its treatment".
Both Voortman and Adesman said more research is needed to fully understand the relationship between ADHD and diet. In the meantime, because kids with ADHD appear more likely to have unhealthy diets, Voortman said it may be important for health care professionals to monitor children's diets and to provide parents with suggestions for healthier choices.
Source: The Journal of Nutrition
"Children's Attention-Deficit/Hyperactivity Disorder Symptoms Predict Lower Diet Quality but Not Vice Versa: Results from Bidirectional Analyses in a Population-Based Cohort"
Authors: Mian. A., et al