Broccoli Extract Shows Promise in Autism

A vegetable extract calms the brain inflammation seen in autism spectrum disorder

STUDY: Zhang X et al, ACS Chem Neurosci 2026 

STUDY TYPE: Review

FUNDING: Ministry of Science and Technology of China, National Natural Science Foundation of China, Hubei Provincial Department of Education

Background

Sulforaphane, a compound in broccoli, boosts the body’s antioxidant defenses and dampens inflammation, both of which run high in autism, making it one of the most studied complementary options for the disorder.

The Study

• This review pulls together seven placebo-controlled trials (10 to 36 weeks) in children, adolescents, and adults with autism.
• It also draws on animal and cell studies mapping the biological pathways, centered on the antioxidant regulator Nrf2, through which sulforaphane may protect the brain.

Findings across trials are mixed. The strongest positive result, in 44 adolescents and adults, showed a 30% drop in Abnormal Behavior Checklist and Social Response Scale scores, though the gains disappeared once sulforaphane stopped.

A 36-week trial in children found improvement on caregiver ratings. A larger, 108-patient Chinese trial found no change on caregiver ratings, but a third of patients improved by 30% or more on clinician-rated scales. A trial in children aged 3 to 7 found no significant improvement on any measure, suggesting younger children may respond less consistently than adolescents and adults.

Animal studies tie sulforaphane’s effects to reduced neuroinflammation and oxidative stress through Nrf2 activation. At doses above 100 to 200 micromoles a day, it can cause nausea and bloating, and most trials to date have been small and inconsistently designed.

Separately, one study found positive results in childhood ADHD.

Dosing

The dosing is confusing because there is an active ingredient (sulforaphane) and its precursor (glucoraphanin, sometimes called sulforaphane-glucosinolate). Either of these may be listed on the product label. Both are acceptable, as glucoraphanin converts into sulforaphane through an enzyme (myrosinase).

Here is how to dose based on those ingredients:

• Adults: Sulforaphane 100–150 µmol (18–26 mg) QD or glucoraphanin 44–64 mg.
• Children: Sulforaphane 25–50 µmol (4–9 mg) QD or glucoraphanin 10–22 mg.
• Can also dose by weight in children: Sulforaphane 0.23–1 mg/lb/day or glucoraphanin 0.57–2.5 mg/lb/day.

Reliable brands include Avmacol and BROQ. Avmacol (ERS92, regular and extra-strength) is a proprietary form made by Nutramax Laboratories and used in clinical trials.

Side Effects

• Most common: Headache and GI distress.
• Serious but rare: None.
• May also improve diabetes and vascular health.

Practice Implications

1. The evidence for sulforaphane in autism is real but inconsistent, and it seems to work better in adolescents and adults than in young children.
2. It is low-risk complementary option, not a replacement for psychotherapy.
3. Have families track key symptoms before and during treatment so you can judge objectively whether it’s helping.
4. Alternatively, patients can eat more broccoli, or other green cruciferous vegetables sources like Bok choy, Brussels sprouts, cabbage, cauliflower, collard greens, kale, mustard greens, and watercress.