Sulforaphane to Reduce Symptoms of Schizophrenia

Inclusion Criteria: * Capacity for written informed consent * Age 18-65 years, inclusive * Diagnostic and Statistical Manual of Mental Disorders, 5th Edition (DSM-5) diagnosis of schizophrenia or schizoaffective disorder as determined by the Structured Clinical Interview for DSM-5 Disorders (SCID-5) * Currently an outpatient at time of screening * Residual psychotic symptoms of at least moderate severity as evidenced by a Positive and Negative Syndrome Scale (PANSS) total score of 60 or higher AND one or more of the following: one or more PANSS positive symptom scores of 4 or higher; OR containing at least three positive or negative items with scores of 3 or higher at the screening visit * Receiving antipsychotic medication for at least 8 weeks prior to enrolling in the study with no antipsychotic medication changes within the previous 21 days from visit 2 (week 0) * Conformance to PORT Treatment Recommendation about Maintenance Antipsychotic Medication Dose * Proficient in the English language * Participated previously in one of our screening studies Exclusion Criteria: * Any clinically significant or unstable medical disorder as determined by the principal investigator and/or the study physician (e.g., HIV infection or other immunodeficiency condition (such as receiving chemotherapy), uncontrolled diabetes, congestive heart failure) * DSM-5 diagnosis of intellectual disability or comparable diagnoses determined by previous versions of the DSM * DSM-5 diagnosis of a moderate or severe substance use disorder, except for caffeine or tobacco, within the last three months prior to the screening visit. If the patient has a positive drug toxicity screen at the time of visit 1 (screening), further evaluation by the investigator will be done of the substance use to determine eligibility. * Any current use of a broccoli supplement (e.g., Avmacol® or other health food broccoli supplement) * Participated in any investigational drug trial in the past 30 days prior to the screening visit * Pregnant, planning to become pregnant, or breastfeeding during the study period