Researchers have warned that a substance found in fish oil, which is commonly taken as a supplement to boost brain function, may have the opposite effect and slow recovery after brain injuries.
The researchers studied mice with traumatic brain injuries. They found that when these mice were given eicosapentaenoic acid (EPA), a key omega-3 fatty acid, their brains took longer to heal.
The researchers say more studies are needed to find out if something similar could happen in people taking these supplements.
"These results challenge the assumption that omega-3 provides uniform neuroprotection after brain injury," the team wrote in the paper published in the journal Cell Reports.
Omega-3 is a type of polyunsaturated fatty acid (PUFA). In general, polyunsaturated fatty acids are essential and healthy fats that should be consumed regularly. They are associated with reduced inflammation, lower blood pressure, and less plaque buildup in the arteries.
Omega-3 specifically supports brain health and is believed to help protect the brain from injuries as well as accelerate recovery.
However, according to experts, there is limited research on the long-term effects of omega-3 after brain injury. Therefore, they decided to study it themselves.
During the experiments, the team used mice that had suffered repeated traumatic brain injuries. However, these injuries were mild enough that the mice would have recovered without long-term damage under a controlled, typical diet.
Then some of the mice were given diets that were relatively rich in eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA), the other major omega-3 fatty acid found in fish oil.
Before the injuries, eicosapentaenoic acid (EPA) levels in the brains of mice remained stable. However, after the injuries, EPA levels were significantly depleted. Furthermore, the researchers found that EPA appeared to impair the repair and remodeling of blood vessels in the brains of mice after injury.
It also appears that the brain instability associated with eicosapentaenoic acid makes mice more susceptible to cognitive decline and the accumulation of abnormal tau protein, a protein associated with many brain disorders, including chronic traumatic encephalopathy (CTE), a degenerative condition caused by repeated traumatic brain injuries.
Meanwhile, levels of docosahexaenoic acid remained stable in the brains of the mice throughout the experiments, and the researchers did not observe any potential adverse effects associated with it.
The researchers also studied brain cells taken from people who died from chronic traumatic encephalopathy. They again found evidence that eicosapentaenoic acid (EPA), not docosahexaenoic acid (DHA), was associated with reduced recovery.
The findings suggest that brain injuries can cause cellular changes that may affect how the brain processes eicosapentaenoic acid (EPA). Therefore, EPA may harm the brain instead of aiding in its healing.
“Fish oil supplements are everywhere, and people take them for a variety of reasons, often without a clear understanding of their long-term effects,” said lead author Dr. Onder Alperam, associate professor at the Medical University of South Carolina, in a statement released by the university. “But from a neuroscience perspective, we still don’t know whether the brain is plastic or resistant to this supplement. That’s why our study is the first of its kind in this field.”
The team's findings are based primarily on mice, so they should be interpreted with caution. Further research is undoubtedly needed to explore the long-term health effects of EPA supplementation in humans, particularly after brain injury. But it is certainly work that needs to be done, the researchers say.
Alper added: "I'm not saying fish oil is absolutely good or bad. What our data highlights is that biology is context-dependent. We need to understand how these supplements behave in the body over time, rather than assuming the same effect applies to everyone."
