In summary, ADHD is a mental disorder whose diagnosis is based on a child manifesting the symptoms of inattention, hyperactivity and impulsivity to the extent that the symptoms impair the child's ability to function. The main beneficial treatments are two nonspecific treatments, stimulant medication and behavioural interventions, preferably in combination. Dietary interventions have included diets that restrict allergenic foods, starting with a generally restricted diet and adding those foods that do not worsen the child's behaviour; a diet that restricts food additives and preservatives, referred to as the Feingold diet; and diets that restrict sugar. These dietary interventions either have not been proved to be efficacious or still require more study to determine their effects.