For decades, omega-3 fatty acids, those celebrated nutrients found in fish, flaxseed, and algae, have been praised for keeping hearts healthy and minds sharp. But a growing body of evidence suggests they may do something even more intriguing: tame human aggression.

A Modest but Meaningful Effect

When researchers aggregated the results, they found that people who took omega-3 supplements showed an average reduction in aggression equivalent to a small-to-moderate effect size (Hedge’s g ≈ 0.22) compared with those given a placebo. This might sound subtle, but in population terms, even modest reductions can have powerful ripple effects, lowering risks of conflict, injury, and emotional distress.

Importantly, the calming effects were consistent across age, gender, and setting—from schoolchildren to adults, from community volunteers to inmates. The benefits appeared whether the aggression was reactive (impulsive, hot-blooded) or proactive (calculated, goal-driven). “Omega-3 appears to take the edge off aggression in general, not just one subtype,” the authors note.

How Omega-3 Shapes the Brain

Why would fatty acids influence behavior at all? The answer lies deep in the structure of the brain. Omega-3s are not just nutrients, they are biological building blocks. DHA, for instance, makes up about a third of the brain’s cell membranes, particularly concentrated in the prefrontal cortex, the region responsible for emotional regulation, impulse control, and decision-making.

Animal and imaging studies suggest that omega-3s help stabilize neuronal membranes, promote synaptic growth, and reduce neuroinflammation. In other words, they help the brain’s braking system work more smoothly. “Prefrontal up-regulation,” as Raine and Brodrick describe it, may explain why omega-3 dampens impulsive outbursts.

Who Benefits, and Why

Unlike medications or psychotherapy, omega-3 supplements seem to work broadly and gently. The review found no meaningful differences in outcomes between men and women, adults and children, or between clinical and non-clinical populations. Nor did the duration or dosage, within reasonable ranges, significantly alter results.

This universality is good news for clinicians: omega-3s could serve as a safe, low-cost adjunct to other treatments for aggression, such as cognitive-behavioral therapy or medication. The authors emphasize that the supplements are not a cure-all, but rather a useful addition to a comprehensive treatment plan.

A Clean Bill of Health

Perhaps most appealing, omega-3s come with an excellent safety record. The U.S. Food and Drug Administration considers daily intakes of up to 5 grams safe—more than twice the highest dose tested in most studies. Reported side effects are mild and infrequent, typically limited to fishy aftertastes or mild stomach upset.

Beyond behavior, omega-3s also confer well-documented benefits for cardiovascular health, inflammation, and even mood disorders such as depression. “It’s a rare case of a supplement that’s good for both body and mind,” the authors write.

The Psychology of Self-Awareness

One curious finding emerged in the analysis: self-reports of aggression showed stronger improvements than reports from outside observers such as teachers or clinicians. This may be because people are better judges of their own motives, whether an outburst stemmed from anger or from cold calculation, while observers see only surface behavior. The discrepancy hints at an important psychological dimension: omega-3s might subtly shift internal emotional states even when outward actions change less dramatically.

The Next Frontier: From Fish Oil to Neurogenetics

Raine and Brodrick caution that much remains to be understood. Future studies, they suggest, should examine how omega-3s alter brain function directly, using imaging tools to track changes in neural connectivity and activity in impulse-control circuits. They also call for research into nutrigenetics, how genetic differences, such as variants in the FADS gene cluster that affect fatty acid metabolism, may determine who responds best to supplementation.

Another open question: Do the benefits persist once supplementation stops, or must omega-3s be maintained continuously? For now, the data suggest short-term gains, but long-term durability remains untested.

From Science to Society

The findings have implications far beyond the laboratory. Aggression drives a spectrum of social ills, from school bullying to domestic violence to criminal recidivism. Even a modest, biologically grounded intervention could yield meaningful public-health benefits. As Raine puts it, “We spend billions on security and incarceration; perhaps we should also invest in nutrition.”

Omega-3s won’t eliminate violence or transform personality overnight. But they remind us that biology and behavior are deeply intertwined, and that sometimes, a healthier brain chemistry starts with something as simple as what’s on our plate.

Reference

Raine A, Brodrick L. Omega-3 supplementation reduces aggressive behavior: A meta-analytic review of randomized controlled trials. Aggress Violent Behav. 2024;78:101956. doi:10.1016/j.avb.2024.101956