Many parents believe that eating any type of sugar causes hyperactivity in children, although this theory remains unproved, according to Dr. Alan Greene, a pediatrician writing on the medical-information website DrGreene.com. However, if your child has fructose intolerance, an inherited condition that makes it difficult for your child to break down and use fructose, eating foods containing fructose could cause behavioral changes. Some infants might also have behavioral changes associated with fructose metabolism. See your child's doctor if you believe he has behavioral issues associated with fructose ingestion.