Various studies have found an association between seafood consumption and a lower risk of dementia.
This may be due to the long-chain n-3 fatty acids found in seafood, which may promote healthy neurological function. On the other hand, seafood is a known source of mercury, which can be damaging to the brain. It’s not well known whether the mercury levels in seafood counteract the protective effects associated with fatty acids.
A group of researchers investigated the association between seafood consumption, mercury levels in the brain, dietary n-3 fatty acids and signs of dementia in the brain. Researchers examined the brains of deceased older adults who were part of a study that followed them in their older years until death. The study involved food frequency questionnaires that assessed, among other things, seafood consumption and fish oil supplement intake. From this, researchers computed n-3 fatty acid intake, while brain autopsies assessed neuropathologies and mercury levels.
Moderate seafood consumption was associated with lower Alzheimer’s disease neuropathology in people with APOE S4 status. APOE is a gene that we all carry, but some of us have a form of that gene called S4 that’s linked to increased risk of Alzheimer’s disease. While seafood consumption was correlated with increased levels of mercury in the brain, the levels weren’t significantly linked to increased brain neuropathology.
This was an observational study so causality cannot be confirmed, but nevertheless, the results suggest that seafood may play a role in supporting brain health, particularly for those with an increased risk of Alzheimer’s disease. Many studies have shown a health benefit associated with substituting a couple of red meat meals a week with fish.