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. Nutrition research over the past twenty years has shown that it is becoming increasingly important to include fish and seafood in an overall healthy diet. This became clear when a nutritional 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 in the Mediterranean food pyramid," explains Oldways president Sara Baer-Sinnott.
Today, nutrition researchers recognize seafood as a staple food group in brain-healthy diets such as the MIND diet and the Mediterranean diet. But what exactly does the research tell us about the connection between seafood, cognition, mood and brain structure?
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 for our bones, DHA is also for our brains.
"The food we eat becomes who we are by changing the makeup of our brains," explains Dr. Joseph Hibbeln, an omega-3 expert, psychiatrist and Benjamin Meeker Distinguished Visiting Professor at the University of Bristol in Great Britain.
Seafood is the leading source of DHA in the diet, so it's not surprising that scientists are drawing 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 large number of studies have found that EPA and DHA reduce small proteins in the brain that promote inflammation and are linked to depression, Alzheimer's disease and cognitive decline. Another study, published in the American Journal of Preventive Medicine, found that people who regularly eat fish have bulkier brains than those who don't. This study found that eating fish - fried or roasted - 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 protect sensitive blood vessels in the brain from subtle damage that can lead to mild cognitive impairment, dementia or stroke, according to research published in 2021 in Neurology. This adds to the growing evidence that seafood supports brain health.
Omega-3 levels can be measured in the body as a measure 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 a lower risk of developing Alzheimer's disease and dementia," explains William Harris, president of the Fatty Acid Research Institute. His research quantifies these relationships in large cohort studies. Although there has not 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, " withholding omega-3 fatty acids would not be ethical in a randomized controlled trial."
"The most pressing and immediate thing in people's lives are the behaviors and emotions that emerge when the brain is deprived of essential nutrients," Hibbeln says. In other words, nourishing our brains is just as important for our mental health as it is for our cognitive health.
An analysis of double-blind, randomized controlled trials of more than 10,000 patients across 35 studies found that giving patients EPA-predominant omega-3 fatty acids could produce significant clinical effects that in some cases were greater than what you would see from antidepressant medications.
Nearly twenty years ago, the American Psychiatric Association concluded that the omega-3 fatty acids EPA and DHA have a protective effect on mood disorders such as depressive disorders and bipolar disorders. And yet Hibbeln still says that "the mental health benefits of omega-3 fatty acids are under-known, under-utilized and under-implemented" within the broader medical community.
The Dietary Guidelines for Americans recommend that adults eat at least 250 grams of seafood per week, but emphasize that pregnant or breastfeeding women should eat no more than 350 grams per week of a variety of seafood, from choices that contain less methylmercury. In the more than two decades since the advisory on mercury and seafood was first issued in the US, dozens of studies have begun to paint a more nuanced picture of this relationship.
Methylmercury was recognized as a neurotoxin when dangerously high levels due to industrial contamination in the 20th century were associated with overt, harmful effects on the brain and nervous system, especially in young children. Although overt harm from extreme exposure has not been reported, much research has since been conducted to better understand the relationship between seafood consumption during pregnancy, exposure to normal background levels of methylmercury in that seafood, and neurodevelopment in children .
More than thirty such studies have now analyzed the data of more than 200,000 mother-child pairs. The studies found little evidence of neurodevelopmental damage associated with that consumption. Instead, the study points to more than 50 cases of benefits to children's neurodevelopment, including improvements in IQ, from seafood consumption by women compared to children whose mothers ate less or no seafood during pregnancy.
In other words, the benefits of eating seafood outweigh the potential risks.
"What we see consistently in these studies is that more than 12 ounces per week is usually better than less than 12 ounces per week," said Philip Spiller, former director of the then-Office of Seafood within the U.S. Food and Drug Administration. and lead author of a recently published study analyzing research results. "The evidence is robust enough that messages to pregnant women should emphasize the likelihood of benefits for their children's neurodevelopment, that more is better than less, and no longer emphasize cautious behavior to avoid risks arising from investigations have not shown."
As it stands now, almost 90% of Americans do not meet the recommended amounts of seafood according to the Dietary Guidelines for Americans.
"If you're obsessed with mercury, you're missing the big picture," says Tom Brenna, PhD, professor of pediatrics, chemistry and 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 generally show great benefits, so the risk is that you're not eating enough seafood."
Seafood cooks faster than chicken, and yet this brain-healthy food group is surprisingly underutilized in the home kitchen. At the grocery store, seafood can be found in fresh, frozen, and canned forms - all of which can be used in delicious and nutritious meals. For people new to seafood, or any food for that matter, remember that taste preferences are not 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 with higher omega-3 content, Harris suggests remembering the acronym SMASH, which stands for salmon, mackerel, anchovies, sardines and herring. "Eat a meal with one of these twice a week," Harris recommends, noting that salmon is one of his favorite choices.
Baer-Sinnott suggests drawing on traditional diets, such as the Mediterranean diet, to experience how seafood fits into healthy eating patterns that are rooted in tradition and culture. "Eating fish and seafood twice a week is good for your health and it's also convenient and tasty," says Baer-Sinnott. "With all this evidence, why wouldn't you?"
"Choose a fillet, put some olive oil in the pan and fry it a little on each side. Don't think about it too much," assures Brenna. A sea of culinary possibilities awaits.
