New research suggests that omega-3 supplements may be an effective tool in reducing aggressive behavior. A recent meta-analysis found that omega-3 supplements can reduce aggression by a small but significant amount. The findings suggest that aggression may be reduced by 28% across a range of demographics and settings. The findings are published in the journal Aggression and violence.
This research grew out of a long-standing interest in the relationship between nutrition and behavior. Omega-3 fatty acids, found in fish and fish oil supplements, are known to be positively associated with brain function. Omega-3 fatty acids are important components of cell membranes and contribute to a variety of brain activities, including promoting neuronal growth, regulating neurotransmitter and gene expression, and supporting nerve cell signaling. They also reduce brain inflammation and improve cerebral blood flow.
Previous studies have shown links between poor nutrition and behavioral problems, including aggression and violence. Given these links, Raine has been investigating whether omega-3 supplements could help mitigate aggressive behavior. Raine has published significant results from five randomized controlled trials conducted in different countries, but she wanted to see whether these effects were consistent across a wider range of studies.
“We’ve previously shown that nutritional deficiencies are a risk factor for aggression, and that early intervention with increased fish consumption two times per week was associated with a 34 percent reduction in crime 20 years later. This led us to look at omega-3s as an active ingredient in that early intervention,” explains study author Adrian Raine, professor at the University of Pennsylvania and author of “The Science of Omega-3s.” Anatomy of Violence: The Biological Roots of Crime.
To find out, Laing conducted a meta-analysis, a statistical method that combines data from multiple studies to look for overall trends. Laing and her colleague Leah Brodrick analyzed 29 randomized controlled trials that explicitly measured aggression. The studies spanned nearly 30 years and involved a total of 3,918 participants. The researchers selected studies that met certain criteria: they involved human subjects, used omega-3 supplements, directly measured aggression, and provided enough data to calculate an effect size.
The studies were collected from seven different databases, including PubMed and Web of Science, and included a variety of populations, from children to adults, and from community samples to clinical populations. The meta-analysis also looked at various adjustment factors, such as age, sex, dosage, and duration of treatment, to see how these factors influenced the aggression-reducing effects of omega-3.
The meta-analysis found that taking omega-3 supplements slightly reduced aggression. When independent samples were considered, the overall reduction in aggression was 16.2%, but increased slightly to 20.4% and 27.8% when independent studies and laboratories were considered, respectively. These consistent rates suggest that omega-3 supplements may be broadly effective across a variety of populations and settings.
“We thought there might be a dose effect, where more omega-3s would have a greater effect, but we weren’t able to see that,” Lane told PsyPost. “It seems like even moderate supplementation of omega-3s can have an effect.”
Interestingly, the study found that omega-3 supplements had an effect on both reactive aggression (impulsive, emotional reactions) and proactive aggression (planned, goal-directed behavior).
Another important aspect of this study is that there is no evidence of publication bias. The researchers used statistical tests to ensure that the positive results were not due to selective publication of studies with significant findings. This strengthens the validity of the conclusions and underscores the reliability of the meta-analysis.
The results provide evidence that “increasing omega-3s through supplements or fish may help reduce aggressive behavior,” Raine said.
Although the results are promising, the study has some limitations. The effect size, although significant, was modest, indicating that omega-3s are not a panacea for aggressive behavior. Also, the study only looked at short-term effects, so more research is needed to determine whether the benefits of omega-3 supplements last in the long term.
“Omega-3s are not a panacea for aggression,” Raine points out, “but we estimate they reduce aggression by about 30 percent, so it’s clear that there are many other factors at play beyond just nutrition.”
Future studies could explore the mechanisms by which omega-3 affects aggression. Because omega-3 plays an important role in brain function, its effects on aggression are likely mediated by changes in brain structure and function. Neurocognitive assessments, brain imaging studies, and functional analysis of neurotransmitters may provide valuable insight into how omega-3 supplements reduce aggression.
“We know that giving prisoners omega-3 supplements reduces aggressive and antisocial behavior in prison, but does it reduce recidivism?,” says Raine. “We have pilot data to suggest it does, but we need long-term randomized controlled trials to test this further.”
“Given the additional psychological and physical benefits of omega-3 supplementation and its ease of implementation, we believe the time has come to implement it in practice and continue to scientifically investigate its long-term effectiveness.”
The study, “Omega-3 Supplements Reduce Aggressive Behavior: A Meta-Analytic Review of Randomized Controlled Trials,” was published online May 19, 2024.
