Autism spectrum disorder
Supplements studied for autism spectrum disorder.
Overview
Eleven supplements are indexed for autism spectrum disorder across 24 studies.
N-Acetyl Cysteine (NAC) (WA 72; medium effect size, high evidence, very high trust) may reduce irritability in children with autism but does not clearly improve hyperactivity, social withdrawal, or repetitive behaviors. Probiotics (WA 68; medium effect size, high evidence, high trust) are rated possibly effective based on indexed trials.
Sulforaphane (WA 52; low effect size, high evidence, medium trust) shows mixed small-study results for irritability and behavior. Ginkgo (WA 40; low effect size, evidence, and trust) did not add benefit to risperidone in one trial, and L-Carnitine (WA 44; low effect size, low evidence, medium trust) has inconsistent small-study findings. See the heatmap and evidence reviews below for all eleven supplements.
Effect graph
Relevant supplements
Relevant supplements sorted by DEX Score.
| N-Acetyl Cysteine (NAC) | ★★★★★ | Medium |
| Probiotics | ★★★★★ | Medium |
| Sulforaphane | ★★★★★ | Low |
| Vitamin B9 (Folate) | ★★★★★ | Low |
| Vitamin D | ★★★★★ | Low |
| Melatonin | ★★★★★ | Low |
| L-Carnitine | ★★★★★ | Low |
| Vitamin A | ★★★★★ | Low |
| Quercetin | ★★★★★ | Low |
| Ginkgo | ★★★★★ | Low |
| Inositol | ★★★★★ | Very Low / None |
Studies
Find individual evidence reviews for supplements sorted by DEX Score.
11 supplements for , and rated at least stars. All purchase bands. No minimum star filter.
N-Acetyl Cysteine (NAC)View supplement →
Consider purchase·★★★★★
How we scored this▸
- Taking N-acetylcysteine may help reduce irritability in children with autism, but it does not improve other symptoms like hyperactivity, social withdrawal, or repetitive behaviors.
- Early studies found benefits for irritability when used alone or with the medication risperidone.
Browse 4 studies·1 meta-analysis
MetaPharmacological and non-pharmacological interventions for irritability in autism spectrum disorder: a systematic review and meta-analysis with the GRADE assessment2024n=3,531
A meta-analysis of 3,531 participants found NAC was among agents showing modest benefit for irritability in autism spectrum disorder, though evidence quality varied.
- Effect
- Benefit
- Population
- Autism spectrum disorder patients
- Participants
- 3,531
- Avg age
- ~9
RCTA randomised, double blind, placebo-controlled trial of a fixed dose of N-acetyl cysteine in children with autistic disorder2017n=102
A 6-month double-blind RCT of 102 children found fixed-dose NAC (500 mg/day) did not significantly reduce autism symptom severity versus placebo.
- Effect
- No Benefit
- Duration
- 6 months
- Dose
- 500 mg/day
- Population
- Children/adolescents
- Participants
- 102
- Ages
- 3.1–9.9
RCTA randomized double blind placebo controlled clinical trial of N-Acetylcysteine added to risperidone for treating autistic disorders2013
An 8-week double-blind RCT found NAC (1200 mg/day) did not significantly improve social functioning in youth with autism versus placebo.
- Effect
- No Benefit
- Duration
- 8 weeks
- Dose
- 1200 mg/day
- Population
- Children/adolescents
- Ages
- 5–16
RCTA randomized controlled pilot trial of oral N-acetylcysteine in children with autism2012n=14
A 4-week pilot RCT of 14 children with autism found oral NAC (900 mg/day) reduced irritability scores versus placebo.
- Effect
- Benefit
- Duration
- 4 weeks
- Dose
- 900 mg/day
- Population
- Men
- Participants
- 14
- Avg age
- 3.2±10.7
ProbioticsView supplement →
Consider purchase·★★★★★
How we scored this▸
- Probiotics are possibly effective for Autism spectrum disorder.
Browse 3 studies·2 meta-analyses
RCTEfficacy and safety of Bacteroides fragilis BF839 for pediatric autism spectrum disorder: a randomized clinical trial2024n=60
In 60 children with ASD, Bacteroides fragilis BF839 20 g/day for 16 weeks improved ABC body-and-object-use scores and GI symptoms versus placebo.
- Effect
- Benefit
- Duration
- 16 weeks
- Dose
- 20 g/day
- Population
- Children/adolescents
- Participants
- 60
- Ages
- 2–10
MetaProbiotics for autism spectrum disorder: An updated systematic review and meta-analysis of effects on symptoms2024n=318
A meta-analysis of 8 ASD RCTs (n=318, ages 1.5–20 years) found probiotic intervention significantly improved behavioral symptoms versus control.
- Effect
- Benefit
- Population
- Children with autism spectrum disorder
- Participants
- 318
- Ages
- 5–20
MetaThe impact of probiotics on core autism symptoms - A systematic review and meta-analysis of randomized clinical trials2024n=630
A meta-analysis of 12 ASD RCTs (n=630) found borderline improvement in core autism symptoms with probiotics (MD −0.21, 95% CI −0.39 to −0.03).
- Effect
- Benefit
- Population
- Children/adolescents
- Participants
- 630
- Ages
- <20
SulforaphaneView supplement →
Reconsider purchase·★★★★★
How we scored this▸
- It is unclear if taking sulforaphane helps people with autism.
- Some small studies have shown slight improvements in irritability, hyperactivity, and social behavior in children and young adults with autism, but these changes may not be meaningful in everyday life.
- Other studies found no clear benefits.
- More research with larger groups is needed to know if sulforaphane is clinically useful for autism.
Browse 5 studies
RCTSulforaphane Treatment in Children with Autism: A Prospective Randomized Double-Blind Study2023
In a prospective RCT in children with autism, sulforaphane improved social responsiveness and behavior scores versus placebo over the treatment period.
- Effect
- No Benefit
- Population
- Children/adolescents
- Ages
- 3–7
RCTRandomized controlled trial of sulforaphane and metabolite discovery in children with Autism Spectrum Disorder2021n=57
In children with autism spectrum disorder, sulforaphane altered urinary metabolites and was associated with behavioral improvements versus placebo in this randomized controlled trial.
- Duration
- 36 weeks
- Population
- Children/adolescents
- Participants
- 57
- Ages
- 3–12
RCTSulforaphane as an adjunctive treatment for irritability in children with autism spectrum disorder: A randomized, double-blind, placebo-controlled clinical trial2020
In children with autism-related irritability, adjunctive sulforaphane plus risperidone did not significantly outperform risperidone alone on irritability scores in this RCT.
- Effect
- Benefit
- Dose
- 0.25 mg/day
- Population
- Children/adolescents
- Ages
- 4–12
RCTIdentification of urinary metabolites that correlate with clinical improvements in children with autism treated with sulforaphane from broccoli2018n=35
In children with autism, sulforaphane treatment correlated with urinary metabolite changes and clinical improvements in social responsiveness versus baseline.
- Effect
- Benefit
- Duration
- 12 weeks
- Population
- Young adults
- Participants
- 35
RCTSulforaphane treatment of autism spectrum disorder (ASD)2014n=29
In young men with autism, sulforaphane derived from broccoli sprout extract improved social interaction and behavior scores versus placebo over 18 weeks.
- Effect
- Benefit
- Duration
- 18 weeks
- Population
- Children/adolescents
- Participants
- 29
- Ages
- 13–27
Vitamin B9 (Folate)View supplement →
Reconsider purchase·★★★★★
How we scored this▸
- It is not clear if taking folic acid during pregnancy reduces the risk of autism in the child.
- However, research combining many studies suggests that taking at least 400 micrograms of folic acid daily during pregnancy is linked to about a 45% lower chance of autism in children aged 2 to 15.
- Taking folic acid from early pregnancy also appears to lower the risk by around 43%.
- This benefit is seen in countries regardless of whether foods are fortified with folic acid.
- One study found that women who started folic acid on the first day of their last menstrual period before getting pregnant had a 39% lower chance of having a child with autism by age 3 to 10 compared to those who did not take folic acid.
- The best reduction in risk seems to occur when folic acid supplementation begins around conception.
Browse 2 studies·1 meta-analysis
MetaPrenatal Folic Acid Supplements and Offspring's Autism Spectrum Disorder: A Meta-analysis and Meta-regression2022
A meta-analysis of 10 studies found that the consumption of a daily amount of at least 400 μg folic acid from dietary sources and supplements, was associated with a reduced risk of offspring ASD [OR 0.55, 95% CI 0.36-0.83].
- Effect
- Benefit
- Dose
- ≥400 μg/day folic acid
- Population
- Pregnant women
ObservationalAssociation between maternal use of folic acid supplements and risk of autism spectrum disorders in children2013n=85,176
A study of 85176 pregnant women found that the adjusted OR for autistic disorder in children of folic acid users was 0.61 (95% CI, 0.41-0.90).
- Effect
- Benefit
- Population
- Pregnant women
- Participants
- 85,176
L-CarnitineView supplement →
Reconsider purchase·★★★★★
How we scored this▸
- Some small studies in children with autism (ages 3 to 16) suggest that taking L‑carnitine daily for 8 to 12 weeks may help with symptoms such as low energy, social withdrawal, hyperactivity, and irritability.
- Results are mixed, and in some studies children were also taking other medicines like risperidone.
Browse 2 studies
RCTEffect of Adding L-Carnitine to Risperidone on Behavioral, Cognitive, Social, and Physical Symptoms in Children and Adolescents With Autism: A Randomized Double-Blinded Placebo-Controlled Clinical Trial2023n=25
In children and adolescents with ASD on risperidone, adding L-carnitine improved behavioral, cognitive, and social scores versus risperidone alone over 8 weeks.
- Effect
- Benefit
- Duration
- 8 weeks
- Dose
- 2 g/day
- Population
- Children/adolescents
- Participants
- 25
RCTA prospective double-blind, randomized clinical trial of levocarnitine to treat autism spectrum disorders2011n=19
In 19 children with ASD, levocarnitine 50 mg/kg/day for 3 months improved some autism rating scores versus baseline with acceptable tolerability.
- Effect
- Benefit
- Duration
- 3 months
- Dose
- 50 mg/kg
- Population
- Children/adolescents
- Participants
- 19
- Ages
- 3–10
MelatoninView supplement →
Reconsider purchase·★★★★★
How we scored this▸
- In one study of children with autism aged 6–15 years, taking 1 mg or 4 mg of melatonin before bed did not improve behavior compared to placebo.
- This study mainly focused on sleep, not behavior.
- In another study, a follow‑up analysis found that children taking prolonged‑release melatonin tablets (2–5 mg nightly for 13 weeks) showed improvements in some outward behaviors compared to placebo.
- However, melatonin did not help with hyperactivity, attention, emotions, or getting along with peers.
- These results should be interpreted with caution, as behavior was not the main goal of the research.
Browse 2 studies
RCTMelatonin Treatment and Adequate Sleep Hygiene Interventions in Children with Autism Spectrum Disorder: A Randomized Controlled Trial2022n=66
An RCT of 196 children with ASD found 1–4 mg melatonin before bedtime shortened sleep-onset latency by 22–28 minutes vs 5 minutes on placebo under structured sleep hygiene.
- Effect
- Benefit
- Dose
- 4 mg
- Population
- Children/adolescents
- Participants
- 66
RCTPediatric Prolonged-Release Melatonin for Sleep in Children with Autism Spectrum Disorder: Impact on Child Behavior and Caregiver's Quality of Life2019n=125
A 13-week RCT of 125 children with ASD found prolonged-release melatonin (2–5 mg) improved externalizing behavior (53.7% vs 27.6% clinically improved) and caregiver quality of life vs placebo.
- Effect
- Benefit
- Dose
- 2–5 mg/day
- Population
- Children/adolescents
- Participants
- 125
- Ages
- 2–17
Vitamin DView supplement →
Reconsider purchase·★★★★★
How we scored this▸
- It’s not clear if taking vitamin D helps people with autism spectrum disorder.
- In one small study of children aged 2.5–8 years, taking vitamin D at 2000 IU daily for a year led to small improvements in irritability and hyperactivity compared with a placebo.
Browse 1 study
RCTA randomised controlled trial of vitamin D and omega-3 long chain polyunsaturated fatty acids in the treatment of irritability and hyperactivity among children with autism spectrum disorder2019n=111
In 111 New Zealand children with ASD given 2000 IU/day vitamin D and/or 722 mg/day DHA for 12 months, both vitamin D and omega-3 reduced irritability versus placebo.
- Effect
- Benefit
- Dose
- 2000 IU/day
- Population
- Children/adolescents
- Participants
- 111
- Ages
- 5–8
GinkgoView supplement →
Reconsider purchase·★★★★★
How we scored this▸
- In a small study, children with autism who took ginkgo extract along with their usual medicine (risperidone) did not show more improvement in symptoms than those who took the medicine alone.
- Ginkgo was safe but did not add benefits.
Browse 1 study
Clinical trialFirst preliminary results of an observation of Ginkgo Biloba treating patients with autistic disorder2009
In 3 autistic patients, ginkgo EGb 761 200 mg/day for 4 weeks showed improvement on the Aberrant Behavior Checklist in an observational study.
- Effect
- Benefit
- Duration
- 4 weeks
- Dose
- 200 mg/day
- Population
- Autism patients
QuercetinView supplement →
Reconsider purchase·★★★★★
How we scored this▸
- It is unclear if quercetin alone helps children with autism.
- A study in kids aged 4 to 10 showed that a combination of luteolin, quercetin, and rutin taken for 26 weeks improved behaviors like hyperactivity and irritability and helped with daily and social skills a little.
- However, the study did not include a comparison group, so more research is needed.
Browse 1 study
Controlled trialAn open-label pilot study of a formulation containing the anti-inflammatory flavonoid luteolin and its effects on behavior in children with autism spectrum disorders2013n=50
In 50 children with ASD (ages 4–10), open-label luteolin/quercetin supplement for 26 weeks improved adaptive behavior and communication on Vineland scales.
- Effect
- Benefit
- Dose
- 100 mg luteolin + 70 mg quercetin/capsule
- Population
- Children/adolescents
- Participants
- 50
- Ages
- 4–10
Vitamin AView supplement →
Reconsider purchase·★★★★★
How we scored this▸
- Children with autism often have low vitamin A levels, which may be linked to more severe symptoms.
- Some early studies suggest that taking a high dose or weekly vitamin A over several months might improve social and communication skills, especially in kids with vitamin A deficiency.
- However, more research is needed to confirm these effects.
Browse 2 studies
A weekly vitamin A supplementary program alleviates social impairment in Chinese children with autism spectrum disorders and vitamin A deficiency2021n=138
A 6-month study of 138 Chinese children with ASD and vitamin A deficiency found weekly-dose vitamin A improved serum retinol and reduced social impairment scores more than standard daily supplementation.
- Effect
- Benefit
- Duration
- 6 months
- Population
- Children/adolescents
- Participants
- 138
Vitamin A improves the symptoms of autism spectrum disorders and decreases 5-hydroxytryptamine (5-HT): A pilot study2018
A pilot study in children with autism spectrum disorder found vitamin A supplementation improved behavioral symptoms and reduced elevated serum 5-hydroxytryptamine levels.
- Effect
- Benefit
- Population
- Children/adolescents
InositolView supplement →
Do not purchase·★★★★★
How we scored this▸
- A plain-language summary is not available for autism spectrum disorder.
- More studies are needed before any benefit can be considered reliable.
Browse 1 study
Clinical trialInositol treatment of autism1997
In 9 children with autism, inositol (200 mg/kg/day) showed no benefit on behavioral symptoms versus placebo in a crossover trial.
- Effect
- No Benefit
- Dose
- 200 mg/kg
- Population
- Children/adolescents
Evidence visualised
Same ratings as above, aggregated so you can see coverage and imbalance.
| Supplement | DEX | Studies | Meta-analyses | Share |
|---|---|---|---|---|
| Sulforaphane | ★★★★★52% | 5 | 0 | 21% |
| N-Acetyl Cysteine (NAC) | ★★★★★72% | 4 | 1 | 17% |
| Probiotics | ★★★★★68% | 3 | 2 | 13% |
| L-Carnitine | ★★★★★44% | 2 | 0 | 8% |
| Melatonin | ★★★★★44% | 2 | 0 | 8% |
| Vitamin A | ★★★★★40% | 2 | 0 | 8% |
| Vitamin B9 (Folate) | ★★★★★48% | 2 | 1 | 8% |
| Ginkgo | ★★★★★40% | 1 | 0 | 4% |
| Inositol | ★★★★★28% | 1 | 0 | 4% |
| Quercetin | ★★★★★40% | 1 | 0 | 4% |
| Vitamin D | ★★★★★44% | 1 | 0 | 4% |