As a daily fish oil supplement taker (partly for brain health, mostly for lowering triglycerides), the findings of a new study are making me hope I never incur a traumatic brain injury.

Those incredible omega-3 fatty acids like EPA and DHA are linked to lower inflammation and better cardiovascular health. But new research suggests they may be doing more damage than they repair in people who have suffered repeated mild traumatic head injuries.

In a study published in Cell Reports, scientists found that eicosapentaenoic acid (EPA) may interfere with the brain’s ability to heal. Instead of aiding recovery, EPA was disrupting blood vessel repair, weakening brain tissue stability, and contributing to the buildup of abnormal tau proteins. Those are associated with neurodegenerative conditions like chronic traumatic encephalopathy, more commonly known as its terrifying three-letter nickname CTE.

Fish Oil Might Get Weirdly Complicated After a Brain Injury

The effect is contextual. Before someone incurred a head injury, EPA levels in the brain were stable. After the injury, those levels dropped significantly, and supplementing with EPA from fish oil appeared to worsen it. Mice that were given EPA-heavy diets showed slower recovery, poorer cognitive performance, and more signs of long-term neurological damage.

DHA, on the other hand, didn’t show the same negative effects, suggesting that not all omega-3’s behave the same way under stress. Researchers also looked at human brain cells and postmortem tissue from people who had CTE. They found similar EPA patterns. The researchers stress that the implication here isn’t that fish oil is inherently bad for you; it’s that the brain is processing it differently after an injury, creating what the researchers describe as a metabolic vulnerability.

Researchers also examined human brain cells and postmortem tissue from individuals with CTE, finding similar patterns specifically linked to EPA. The implication is not that fish oil is inherently harmful, but that the brain may process it differently after injury, creating what researchers describe as a “metabolic vulnerability.”

Of course, there were your requisite caveats. This is, after all, primarily a study of mice, and as with most such studies, mice make for a decent enough analog for human physiology, but the minor differences between species could mean that the findings apply only to mice. Follow-up studies will have to see how all this translates to humans.

Still, it provides researchers with a new direction, one that may help people who have suffered head trauma.