Fish oil may increase CTE risk after brain injury, with a study suggesting the common supplement could worsen the long-term effects of repeated head knocks.
CTE is a degenerative brain condition linked to repeated head impacts, including so-called mild concussions in contact sports.
Symptoms such as mood swings, memory loss and depression may not appear for decades.
“Fish oil is widely seen as neuroprotective,” said Semir Beyaz, a research assistant at Cold Spring Harbor Laboratory in the US.
Despite this popular notion, there is surprisingly little long-term evidence of its effectiveness after repetitive brain injuries.
Beyaz, graduate student Onur Eskiocak and their collaborators initially assumed these popular supplements would be as beneficial as advertised.
“Surprisingly, in mice, they made things much worse,” Beyaz said.
The team, which included Beyaz’s longtime collaborator Onder Albayram at the Medical University of South Carolina, developed a mouse model using a fish oil-based diet and collected additional samples from patients diagnosed with CTE.
From there, they focused on a common fatty acid in fish oil supplements called EPA. In mice, rather than aiding recovery, EPA altered the brain’s metabolic response and disrupted repair efforts. Excess EPA was also found in human tissue.
To recover from injuries, the brain often builds new blood vessels to help restore oxygen and blood flow. EPA is known to block this process.
In some cases, such as certain cancer treatments, that can be useful. After traumatic brain injuries, however, EPA can interfere with the brain’s natural repair and recovery processes.
Over time, this can increase the long-term risk of developing conditions such as CTE.
Despite their findings, the team cautioned against sweeping generalisations.
“This idea of fish oil being a one-size-fits-all benefit doesn’t work once you start investigating interactions,” Eskiocak said.
“But that doesn’t mean it’s bad for you.”
“We know fish oil benefits your heart and gut,” Beyaz added. “But context matters, especially when it comes to injury and recovery.”
While the discovery may have implications for nutrition, therapeutic strategies and dietary interventions, more questions must be answered before the full picture becomes clear.
For example, two boxers may suffer the same number of knockouts during their careers, with only one of them developing CTE while the other stays relatively healthy.
Scientists still are not sure why, but this study brings them one step closer to understanding how factors such as diet and nutrition affect brain health over time.
