Seafood, a source of essential fatty acids, is often celebrated for its health benefits; but it can also contain mercury, a chemical known to increase the risk of brain disorders. So, is seafood actually healthy? A group of researchers may have put this fishy conundrum to bed—at least for people with a genetically increased risk for Alzheimer’s disease. They found that regularly eating seafood could help reduce the likelihood of developing Alzheimer’s disease in that high-risk group, and that higher brain mercury concentrations, associated with consuming fish, were not correlated with brain disease occurrence. The study was published in JAMA and looked at data from 286 adults who participated in a study called the Memory and Aging Project and who died between 2004 and 2013. At enrollment, the participants were dementia-free, and their average age of death was 90 years.
As part of the Memory and Aging Project, participants answered food surveys that included questions about their seafood and fish oil consumption. Researchers measured mercury concentrations in brain samples from the 286 subjects and tested their cells for a genetic marker associated with an increased risk for Alzheimer’s disease. Comparing this information with data from the food surveys, researchers discovered that brain mercury concentrations were closely correlated with the amount of seafood participants reported eating each week. The researchers then adjusted the data for other factors, including age, sex, education, and total energy intake, and found that:
In participants with a genetic risk for developing Alzheimer’s disease, those who ate seafood at least once a week had less of a chance of developing the disease and fewer signs of brain tissue injuries than participants who did not eat seafood. Among participants without the genetic risk, the chance of developing Alzheimer’s disease was the same in seafood eaters and non-seafood eaters.
Taking fish oil supplements appeared to protect against certain types of brain tissue injuries in people carrying the genetic risk for Alzheimer’s disease.
Higher brain mercury concentrations were not associated with any brain tissue injuries, regardless of genetic risk for Alzheimer’s disease.
Participants with a higher intake of a-linolenic acid, an omega-3 fatty acid from plants, had fewer brain tissue injuries related to blockages in blood flow compared with participants with lower intakes.
Eating seafood has been associated with a number of health benefits including improvements in age-related vision and mood-disorders, lowered risk of heart disease, and improved cognitive function in older adults. These are just some of the reasons why the US Dietary Guidelines recommend eating fish two to three times per week. So, if you’re ready to up your fish intake, baked salmon fillets, catfish tacos, or canned sardines on toasted bread all make for quick and easy meals.