Which dietary supplement harms the brain — scientists answer

American neuroscientists have found that eicosapentaenoic acid (EPA) in fish oil may slow brain recovery after traumatic brain injuries. A study on mice showed that EPA interferes with blood vessel regeneration and promotes the accumulation of toxic tau proteins. Docosahexaenoic acid (DHA) did not produce this effect.

American neuroscientists have presented the results of a major 2026 study that calls into question the unconditional benefits of fish oil for the brain. Researchers found that eicosapentaenoic acid (EPA), one of the main omega-3 fatty acids in fish oil, can significantly hinder brain recovery after traumatic brain injuries. Experiments on mice that suffered mild traumatic brain injury showed that animals fed a diet high in EPA performed noticeably worse on learning and spatial memory tasks. Scientists determined that EPA interfered with blood vessel regeneration by altering metabolic processes. Neuroscientist Onder Albayram emphasized that fish oil supplements are widely taken, but their long-term effects on the brain remain unstudied. Docosahexaenoic acid (DHA) did not impede the restoration of the blood-brain barrier, while EPA accumulated in the brains of injured animals and contributed to the buildup of toxic tau proteins. Analysis of brain tissue from humans with chronic traumatic encephalopathy revealed similar abnormalities. Scientists suggest that excess EPA may exacerbate the effects of repeated concussions, but this requires clinical verification.