Rumor has it that one of the oldest known recipes in the Mediterranean – found in "Deipnosophistae" by the ancient Greek Athenaeus – is a recipe for fish (grilled fish sprinkled with grated cheese). For millennia, seafood has played an important role in Mediterranean cuisine, health and culture. In fact, nutrition research over the last 20 years has revealed the increasing importance of including fish and seafood in an overall healthy diet. This was evident when a nutrition science panel met in 2008 to update Oldways’ original Mediterranean Diet Pyramid.
“One of the most notable updates was to make fish and seafood more prominent on the Mediterranean diet pyramid,” explains Oldways President Sara Baer-Sinnott.
Today, nutrition researchers recognize seafood as a staple food group in brain-healthy diets like the MIND diet and the Mediterranean diet. But what exactly does the research us about the link between seafood, cognition, mood and brain structure?
Omega-3s for Brain Health
DHA, or docosahexaenoic acid, is an omega-3 fatty acid that is a building block of our brain. In other words, just as calcium is to our bones, DHA is to our brains.
“The foods we eat become who we are by changing the composition of our brains,” explains Dr. Joseph Hibbeln, an omega-3 expert, psychiatrist and the Benjamin Meeker Distinguished Visiting Professor at the University of Bristol in the UK.
Seafood is the main source of DHA in the diet, so it’s not surprising that scientists are making note of links between eating seafood and brain health. Seafood also contains protein, essential vitamins and minerals, and EPA, or eicosapentaenoic acid, another type of omega-3 fatty acid that supports brain health.
A body of research has found that EPA and DHA reduce small proteins in the brain that promote inflammation and are associated with depression, Alzheimer’s disease and cognitive decline. Another study, in the American Journal of Preventive Medicine, found that people who regularly eat fish have more voluminous brains than those who do not. This study found that eating fish – baked or broiled – is associated with larger gray matter volumes in brain areas responsible for memory and cognition in healthy elderly people.
Eating fish at least twice a week may shield delicate blood vessels in the brain from subtle damage that can lead to mild cognitive impairment, dementia or stroke, according to research published in Neurology in 2021, adding to the growing evidence that seafood supports brain health.
Omega-3 levels can be measured in the body as a marker of how much seafood and/or omega-3 supplements people consume.
“Higher levels of omega-3 measured in plasma or red blood cells are associated with lower risk for developing Alzheimer’s and dementia,” explains William Harris, president of the Fatty Acid Research Institute. His research quantifies these relationships in large cohort studies. While there hasn’t yet been a large randomized-controlled trial measuring seafood intake or omega-3 fatty acid intake as a way to prevent dementia, Harris explains that at this point, given the consistency of the evidence, “to withhold omega-3 fatty acids would not be ethical in a randomized controlled trial.”
Mental Health Benefits of Seafood
“The most pressing and immediate thing in peoples live is the behaviors and emotions that emerge when brain is deficient and critical nutrients,” says Hibbeln. In other words, keeping our brains nourished is just as important for our mental health as it is for our cognitive health.
An analysis of double-blind randomized controlled trials encompassing more than 10,000 patients across 35 studies found that giving patients EPA-predominant omega-3 fatty acids was able to produce significant clinical effects that were, in some cases, greater than what you would see from antidepressant medications.
Nearly 20 years ago, the American Psychiatric Association concluded that omega-3 fatty acids EPA and DHA have a protective effect in mood disorders like major depressive disorder and bipolar disorder. And yet still today, Hibbeln says that “the mental health benefits of omega-3 fatty acids are underknown, underutilized and under implemented” within the greater medical community.
Mercury Concerns
The Dietary Guidelines for Americans recommend that adults eat at least 8 ounces of seafood per week, but emphasize that pregnant or breastfeeding individuals should not exceed 12 ounces per week of a variety of seafood from choices that are lower in methylmercury. However, in the more than 20 years since cautionary advice on mercury and seafood was first issued in the U.S., dozens of studies have started to paint a more nuanced picture of this relationship.
Methylmercury was recognized as a neurotoxin when dangerously high levels from industrial contamination events in the 20th century were linked to overt, damaging effects on the brain and nervous system, particularly in young children. While overt harm from extreme exposures have not been reported again, considerable research has been conducted since then to better understand the relationship between seafood consumption during pregnancy, exposure from normal background levels of methylmercury in that seafood and neurodevelopment in children.
Over 30 such studies have now analyzed data from more than 200,000 mother-child pairs. The studies have found little evidence of harm to neurodevelopment associated with that consumption. Instead, the research points to over 50 incidences of benefits to children’s neurodevelopment, including improvements to IQ, from the women’s consumption of seafood as compared to children whose mothers ate less or no seafood during pregnancy.
In other words, the benefits of eating seafood outweigh any potential risks.
“What we see consistently in those studies is that over 12 ounces per week tends to be better than under 12 (ounces per week),” says Philip Spiller, former director of the then-Office of Seafood within the United States Food and Drug Administration and lead author of a recently published study that analyzed the research results. “The evidence is robust enough that messaging to pregnant women should emphasize the likelihood of benefits to their children’s neurodevelopment, that more is better than less, and should no longer emphasize cautionary behavior to avoid risk that the studies have not found.”
As it stands, nearly 90% of Americans are falling short of recommended seafood amounts according to the Dietary Guidelines for Americans.
“If you obsess on mercury you’re missing the big picture,” says Tom Brenna, PhD, professor of pediatrics, of chemistry, and of nutrition at the Dell Medical School and the College of Natural Sciences at the University of Texas at Austin, and Professor Emeritus at Cornell University. “The studies overall show great benefit, so the risk is not eating enough seafood.”
Buying and Cooking Seafood
Seafood cooks quicker than chicken, and yet this brain-healthy food group is surprisingly underutilized in home kitchens. At the supermarket, seafood can be found in fresh, frozen and canned forms – all of which can be used in delicious and nutritious meals. For people who are new to seafood, or any food for that matter, remember that taste preferences aren’t set in stone. Making an effort to try seafood often and in different forms is a great way to nurture a taste for this popular protein source.
When identifying seafood options higher in omega-3 content, Harris suggests remembering the acronym SMASH, which stands for salmon, mackerel, anchovies, sardines and herring. “Twice a week, eat a meal with one of these,” recommends Harris, noting that salmon is one of his go-to choices.
Baer-Sinnott suggests taking a cue from heritage diets, like the Mediterranean diet, to experience how seafood fits into healthy eating patterns rooted in tradition and culture. “Eating fish and seafood twice a week is good for your health and it is also easy and delicious,” says Baer-Sinnott. “With all of this evidence, why wouldn’t you?”
“Pick a fillet, throw some olive oil right in the pan and cook it a little bit on each side. Don’t overthink it,” assures Brenna. A sea of culinary possibility awaits.