This double blind, randomised controlled trial examines the effect of a commercially available nutritional supplement on behaviour of ADHD patients, as well as on their physical and psychiatric co-morbidities, and level of oxidative stress and immune activity, as compared to placebo and standard pharmaceutical treatment for ADHD.

Inclusion Criteria:

• The patient is between 6-12 years old (both inclusive).
• The patient satisfies the DSM-IV criteria for ADHD or ADD.
• The patient has a responsible caregiver who is able to provide information about the patient's functional status.
• Written informed consent is obtained from the patient and the legally accepted representative.

Exclusion Criteria:

• The patient does satisfy the DSM-IV for autism spectrum disorder.
• The patient does have situational hyperactivity, pervasive developmental disorders, schizophrenia, other psychotic disorders such as mood or anxiety disorder, personality disorder as unsocial behaviour, personality change due to a general medical condition, mental retardation (IQ < 70), understimulating environments, conduct disorder, chorea and other dyskinesias. The patient does not have tics or Tourette's syndrome, or personal or family history of psychotic disorder, bipolar illness, depression, or suicide attempt.
• The patient does have any chronic medical disorder (diabetes, epilepsy or other seizure disorder, autoimmune disorder, gastrointestinal disorder, renal or cardiovascular disorders, etc.) or acute inflammatory disease. The patient does not have glaucoma, heart disease, heart rhythm disorder, high blood pressure, or peripheral vascular disease such as Raynaud's syndrome.
• The patient did use any of these medications during the 3 months before entering the study: clonidine, guanethidine, blood thinners (e.g. warfarin or Coumadin), antidepressants (e.g. amitriptyline, citalopram, doxepin, fluoxetine, nortriptyline, paroxetine, sertraline), cold or allergy medicine that contains a decongestant, medications to treat high or low blood pressure, seizure medicine (e.g. phenobarbital, phenytoin, primidone), or diet pills.
• The patient did take MAO inhibitor (isocarboxazid, linezolid, phenelzine, rasagiline, selegiline or tranylcypromine) in the past 14 days.
• The patient has any other contraindication for the use of methylphenidate.
• The patient did use vitamin/mineral/herbal/omega-3 supplements or other any medication (psychoactive medication, antibiotics, anti-inflammatory drugs, melatonin, etc.) > 1 week during the 3 months before inclusion.