Efficacy of Antioxidant-Based Pharmacological Therapies in Autism Spectrum Disorder: A Systematic Review.
Antioxidant supplements show spotty, mild gains for irritability and social signs—stick with behavior plans first.
01Research in Context
What this study did
Ramírez-Guerrero et al. (2025) hunted every paper that tested antioxidant pills or powders in autistic people. They found trials on sulforaphane, N-acetyl-cysteine, vitamins C and E, and other supplements.
The team compared scores on irritability, social talk, and repetitive acts before and after the pills. They asked: do any of these antioxidants work as stand-alone help?
What they found
Results were all over the map. A few kids looked calmer, some showed no change, and side effects like tummy pain popped up.
No single antioxidant earned a green light for solo use. The authors say keep behavior plans front and center; pills stay back-up only.
How this fits with other research
Christian et al. (1997) already showed zero benefit for high-dose vitamin B6 plus magnesium in a small RCT. Sofía’s wider sweep confirms that antioxidant vitamins rarely beat placebo.
Gallagher et al. (2012) saw tiny parent-noticed gains after hyperbaric oxygen, but without a control group. The new review agrees: parent reports can look hopeful until stricter controls are used.
Parrella et al. (2026) found CBD oil cut anxiety yet did not move core social scores. The same mixed story shows up here—irritability may dip while social symptoms stay put.
Boudreau et al. (2015) showed naltrexone can lower irritability in most kids. Antioxidants help far fewer, so naltrexone keeps the irritability edge for now.
Why it matters
When parents ask about broccoli pills or NAC, you now have clear data: maybe small bonus, no sure thing. Run your regular ABA program, track irritability with an ABC log, and let the doctor handle any supplement trial. If irritability is the big target, naltrexone has better odds than antioxidants, but skills teaching still leads.
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02At a glance
03Original abstract
PURPOSE: Autism Spectrum Disorder (ASD) is a heterogeneous neurodevelopmental condition characterized by persistent deficits in social interaction and communication. This study aimed to evaluate the efficacy of antioxidant-based pharmacological therapies for psychiatric symptoms in patients with ASD. METHODS: A systematic review was conducted using four databases: PubMed, Scopus, ClinicalTrials.gov and Cochrane - Ovid. 20 studies were included. Risk of bias assessment was performed using the Cochrane Risk-of-Bias tool for randomized trials. A descriptive analysis synthesized the main findings. A qualitative value was given to each antioxidant therapy according to its effect on every symptom (improved, not improved or no information), data was visually reported using ChatGPT 4.0 and Google Collab. PROSPERO ID: CRD42023490581. RESULTS: There was a heterogeneous response to antioxidant therapies for ASD symptoms. The use of sulforaphane reported improvement in irritability, stereotypic/repetitive behavior, social cognition/interaction, social communication, hyperactivity and lethargy. Similarly, N-Acetylcysteine evidenced improvement in terms of irritability, stereotypic/repetitive behavior, social cognition and hyperactivity. L-Carnosine improved social cognition and communication, omega-3/omega-6 fatty acids improved social cognition, coenzyme q-10 showed improvement in sleep disorders, and glutathione in repetitive behaviors and irritability. CONCLUSION: Antioxidant-based pharmacological therapy evidenced contrasting responses to a variety of core symptoms in ASD. Despite significant evidence of improvement in some ASD symptom scales, there is still a lack of evidence to justify the use of antioxidant therapies as monotherapy in individuals with ASD.
Journal of autism and developmental disorders, 2025 · doi:10.3168/jds.2015-10005