While limited evidence suggests that omega-3 supplementation may reduce antisocial behavior in children, studies have not reported on posttreatment follow-up and most treatment periods have been of short duration. This study tests the hypothesis that omega-3 supplementation over 6 months will reduce behavior problems in children both at the end of treatment and at 6 months post treatment.

In this randomized, double-blind, placebo-controlled, stratified, parallel-group trial, a community sample of 8-16 year old children were randomized into a treatment group (N = 100) and a placebo-control group (N = 100). The supplementation consisted of a fruit drink containing 1 g/day of omega-3 or a placebo consisting of the same fruit drink without omega-3. Participants, caregivers, and research assistants were blinded to group assignment. The primary outcome measures of externalizing and internalizing behavior problems were reported by both caregivers and their children in a laboratory setting at 0 months (baseline), 6 months (end of treatment) and 12 months (6 months post treatment), together with the secondary outcome measures of parental antisocial behavior. Data were analyzed on an intention-to-treat basis including all participants. Trial registration:

RESULTS: Significant group × time interactions were observed with the treatment group showing long-term improvements in child behavior problems. The average posttreatment effect size was d = -.59. Effects were documented for parent reports, but with the exception of proactive and reactive aggression, child-report data were nonsignificant. Parents whose children took omega-3 showed significant posttreatment reductions in their own antisocial and aggressive behavior. This improvement in caregiver behavior partly mediated the improvements observed in child behavior.

Findings provide initial evidence that omega-3 supplementation can produce sustained reductions in externalizing and internalizing behavior problems. Results are the first to report improvements in caregiver behavior, and to establish this improvement as a part-mechanism for the efficacy of omega-3.