Inclusion Criteria:  -Traumatic Brain Injury  Head trauma greater than two years prior manifesting in one or more of the following:  Loss of consciousness Post-traumatic amnesia Focal neurologic deficits Seizures Persistent symptoms of increased arousal (e.g., difficulty falling or staying asleep, anger and hypervigilance) Impairment in cognitive, social, occupational, or other important areas of functioning (e.g., problems with work and relationships)  Exclusion Criteria:  Traumatic Brain Injury  Unwilling to give consent. Patients with rights managed by Legal Authorized Representative must consent to participate in addition to consent from their legal agent < 2 years post-injury Known allergy to study agent.  Other medical condition or medication administration deemed exclusionary by the study investigators.  Inclusion Criteria:  Healthy Control  Ages 18 to 70 years Works at Centre for Neuro Skills  Participant is willing and able to give informed consent for participation in the study.  Exclusion Criteria  Healthy Control  Subjects with a history of inflammatory bowel disease, Celiac disease or active diverticular disease. Known allergy to study agent. Other medical condition or medication administration deemed exclusionary by the study investigators.