Eat fish, it’s good for you, it’s brain food. Don’t eat fish, it has mercury in it, it’s bad for you. Both statements are true. There are multiple studies that show a diet that includes fish and Omega-3 fatty acid can help protect the brain against memory loss and other neurological disease. Studies also show that mercury is known neurotoxin and consuming fish with high levels of mercury can have serious effects on the brain. These two contradictory ideas make it difficult to know what is really best in terms of a healthy diet with the benefits of fish and without the risks associated with mercury.
There could be some answers however, with a new study conducted at Rush University Medical Center. In the February 2 issue of JAMA researchers at Rush detailed their findings on the link between mercury concentration in the brain, neuropathology and diseases that result in dementia. It’s the first research of its kind to link these factors.
While the team did find that mercury levels in the brains of people who consumed seafood were higher than those who did not, this difference was not associated with increased incidence of brain damage or forms of dementia.
Martha Clare Morris, professor of epidemiology at Rush University led the study which involved data from 286 patients who had agreed to donate their organs to science after their death and who also had completed detailed food questionnaires. This database also included autopsy analyses that provided enough date for Morris to measure levels of mercury and the existence of Alzheimer’s plaques and tangles.
In a press release
, Morris said, “Seafood consumption is promoted for its many health benefits even though it's contaminated by mercury. Since mercury is a known neurotoxin, we wanted to determine whether seafood consumption is correlated with increased brain mercury levels in older adults, and also whether seafood consumption or brain mercury levels are correlated with brain neuropathologies.
While it may have been expected that higher mercury levels would correlate to higher levels of Alzheimer’s and other dementias, this was not the case
. Despite the increased levels, seafood consumption was linked to less cases of Alzheimer related neuropathologies, but with one catch. The patients who consumed more seafood, had higher mercury levels and yet had lower rates of Alzheimer’s all had the genotype APOE-ε4 in common. This genotype is associated with a higher risk of Alzheimer’s disease, leading Morris and her colleagues to surmise that the seafood was a protective factor in patients at risk for developing dementia.
The study also found that among those who consumed seafood at specific amounts and did develop Alzheimer’s the thickness of the amyloid plaques were less dense and the tangles within the neurons were less severe.
In an interview with Time
Professor Morris stated, “The take-home message is that the concern about eating seafood because of mercury should be allayed somewhat by this study since we didn’t see any evidence that increased levels of mercury in the brain is causing brain pathologies.” Check out the video below to learn more about the study.