A popular supplement often taken for its brain-boosting potential may have a dark side. Recent research suggests that an ingredient found in fish oil could have a counterproductive effect on the brain, at least under certain circumstances.
Scientists studied mice with traumatic brain injuries. When these mice were given eicosapentaenoic acid (EPA), a major omega-3 fatty acid, their brains took longer to heal, they found. More study is needed to know whether something similar could happen in people taking these supplements, the researchers say.
“These findings challenge the assumption of uniform omega-3 neuroprotection after brain injury,” they wrote in their paper, published late last month in the journal Cell Reports.
Something fishy
Omega-3s are a type of polyunsaturated fatty acid (PUFA). Generally, PUFAs are considered an essential and healthy kind of fat to regularly consume. They’re linked to lower inflammation, lower blood pressure, and the reduced build-up of plaque in our arteries. Omega-3s in particular also support brain health and are thought to help protect the brain from injuries as well as speed up recovery.
According to the authors, though, there’s been limited research on the long-term effects of omega-3s following brain injury. So they decided to study it for themselves.
For their experiments, they used mice that were given repetitive traumatic brain injuries. These injuries were mild enough, however, that the mice would recover without long-term damage under a typical controlled diet. Some of the mice were then given diets relatively high in EPA and docosahexaenoic acid (DHA), the other major omega-3 found in fish oil.
Before their injuries, levels of EPA in the brain remained steady in the mice. Afterward, though, EPA levels dramatically depleted. What’s more, the researchers found that EPA seemed to impair the repair and remodeling of blood vessels in the mice’s brains following injury. The brain instability linked to EPA also appeared to make the mice more vulnerable to cognitive decline and the build-up of abnormal tau, a protein linked to many brain disorders, including chronic traumatic encephalopathy (CTE), a degenerative condition caused by repeated traumatic brain injuries.
Meanwhile, DHA levels stayed stable in the mice’s brains throughout the experiments, and the researchers spotted no potentially harmful effects linked to it. The researchers also studied the brain cells taken from people who died with CTE. And they once again found evidence that EPA, but not DHA, was linked to reduced healing.
The team’s results suggest that brain injuries can cause changes in cells that can affect how EPA is processed by the brain. Subsequently, EPA might then actually harm rather than help heal the brain.
“Fish oil supplements are everywhere, and people take them for a range of reasons, often without a clear understanding of their long-term effects,” lead study author Onder Albayram, an associate professor at the Medical University of South Carolina, in a statement from the university. “But in terms of neuroscience, we still don’t know whether the brain has resilience or resistance to this supplement. That’s why ours is the first such study in the field.”
What should this mean for fish oil lovers?
The team’s findings are mostly based on mice, so they should be viewed with some caution. It will undoubtedly take more studies to tease out the long-term health implications of EPA supplementation in people, particularly after a brain injury. But it’s certainly work that should be carried out, the researchers say.
“I am not saying fish oil is good or bad in some universal way,” Albayram said. “What our data highlight 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.”
The researchers plan to continue studying how the human body processes and use EPA.
