According to a study, a molecule found in fish and other seafood may play a role in protecting and improving the cognitive functions of the brain.
Researchers investigated the role of trimethylamine N-oxide (TMAO), which is found in people’s diets and produced by the body during fish digestion.
It is broken down by bacteria in the intestine when foods containing TMAO are ingested.
The breakdown product is absorbed into the bloodstream and converted back to TMAO, which interacts with organs throughout the body, the researchers say.
The circulatory and vascular system of the brain is exposed to TMAO, which interacts directly with the blood-brain barrier.
Potentially harmful toxins in the body are prevented from reaching the brain by this barrier.
However, as people age, the blood brain barrier becomes permeable and more easily penetrated by these toxins.
Their new study found that TMAO makes the blood-brain barrier less leaky.
According to research, the long-term presence of TMAO in the diet positively influenced both blood-brain barrier integrity and cognition in mice – preventing recognition memory impairment – compared to l absence of the molecule.
Researchers at Nottingham Trent University and Queen Mary University in London argue the findings have implications for dietary interventions in humans that target the gut-to-brain connection to potentially improve cognitive function.
Professor Lesley Hoyles, a microbiologist at the School of Science and Technology, Nottingham, said: “This work is a big step forward to better understand how our diet could positively influence cognitive function and healthy aging. “
She added: “The metabolites produced by the microbiota come from gut bacteria and have many effects on our body.
“We have shown that TMAO – a bacterial metabolite associated with the human gut microbiome and found in high amounts in fish and seafood – has a direct and beneficial interaction with the blood-brain barrier and influences cognitive function.
“This opens up a range of new work exploring dietary interventions that connect the gut and the brain.”
Lead author Dr Simon McArthur, Institute of Dentistry, Queen Mary University, London, said: “We know that damage to blood vessels in the brain is a hallmark of many neurological diseases, including strokes and dementia.
“By identifying gut bacteria as capable of altering the integrity of blood vessels in the brain, our findings open up exciting new avenues for protective intervention through diet manipulation.
“We’ve long known that eating fish is good for your brain – now we can add gut bacteria as a new side to that old saying. “
The study is published in the journal Microbiome.