Eating fish regularly may shield delicate blood vessels in the brain from subtle damage that can lead to mild cognitive impairment, dementia, or stroke, according to recent research. Published in Neurology in November 2021, the study adds to the emerging evidence that seafood seems to support brain health.

For the study, French researchers analyzed MRIs and food surveys from 1,623 older adults with no history of dementia, stroke, or cardiovascular disease. Those who ate fish at least twice a week were less likely to have signs of blood vessel damage in the brain than those who consumed fish no more than once a week. The benefit was most pronounced in participants ages 65 to 69, and was not statistically significant among those 75 and older— possibly because cerebral blood vessel damage increases with age.

“This study is unique because it couples food questionnaires with magnetic resonance brain imaging in a large group of people,” says Louise D. McCullough, MD, PhD, chair of the department of neurology and a vascular neurologist at the University of Texas McGovern Medical School in Houston. “Most prior studies of fish consumption and of the beneficial omega-3 fatty acids in fish have not done much imaging, especially not of the vasculature and white matter structures of the brain.”

A computer algorithm analyzed the MRI scans to detect three signs of blood vessel problems: white matter hyperintensities (areas where nerve fibers that carry signals deep within the brain have degenerated due to damage of smaller blood vessels in the brain), destruction of brain tissue due to inadequate blood flow and oxygen, and enlargement of fluid-filled spaces that surround blood vessels in the brain. All three signs have been linked with higher risk for memory problems, Alzheimer's disease, and stroke.

“These markers of blood vessel disease are commonly found in the brains of older persons,” says lead researcher Aline Thomas, PhD, an epidemiologist at the Bordeaux Population Health Research Center whose work focuses on neuroscience. “They can be detected with MRI before the manifestation of overt disease, including stroke and dementia.”

Dr. McCullough says that while this new study had some limitations, such as not asking volunteers about the types of fish they ate and relying on self-reports of their diets, its close look at the brain opens new avenues of research for understanding biological links between food and healthy brain aging. The study also suggests a way to guard against cerebral blood vessel damage, says Dr. Thomas. “The recommendation of regular fish consumption may be a relatively simple and inexpensive preventive strategy.”

“Previous studies reported associations between eating fish and protection against cognitive decline and risk of dementia in later life,” says Dr. Thomas. “However, the specific biological mechanisms are still unclear.”

One theory is that the omega-3 fatty acids—particularly docosahexaenoic acid—in certain types of fish are the building blocks of brain and nervous system tissue.

Omega-3s, as well as vitamin D and selenium in fish, may nurture tiny vessels in the brain by helping control blood pressure and discouraging plaque buildup in artery walls, says Dr. Thomas. The nutrients also support the health of arteries and veins, she says, by reducing inflammation and keeping endothelia (blood vessel linings) relaxed, which discourages blood clot formation. Dr. McCullough says fish eaters also may be more likely to consume an overall healthy diet full of fiber-packed produce, whole grains, and nuts that some gut bacteria convert into brain-friendly fatty acids.

Adding Fish to Your Diet

Only about 20 percent of American adults eat at least eight ounces of fish (about two servings) per week, as recommended by government dietary guidelines, according to a 2018 report from the National Center for Health Statistics. Keep these tips in mind when putting more fish on your plate.

Use healthy cooking methods. “How you prepare fish matters,” says Louise D. McCullough, MD, PhD, chair of the department of neurology at the University of Texas McGovern Medical School in Houston. Instead of frying, grill or broil it— you'll use less butter or oil and save calories by not breading the fish. Or bake fish in a foil packet with herbs and some vegetables, suggests nutritionist Melissa Majumdar, MS, RD, of Emory University Hospital Midtown in Atlanta, a spokesperson for the American Academy of Nutrition and Dietetics.

Choose fish high in omega-3s. Salmon, trout, whitefish, sardines, anchovies, herring, mackerel, black cod, and cobia are all rich in omega-3s, healthy fats that provide benefits for the heart, lungs, immune system, and, apparently, the brain.

Be smart about mercury. Large fatty fish that eat smaller fish often have higher concentrations of mercury and other pollutants in their flesh, Dr. McCullough says. These include shark, swordfish, king mackerel, tilefish, and orange roughy, according to the Environmental Protection Agency (EPA). Among canned varieties, white tuna has three times more mercury than light tuna. For more details, check the EPA's fish chart and look for types low in mercury. The chart gives serving recommendations for pregnant and breastfeeding women and for children, but the information on “best,” “good,” and “choices to avoid” can be used by everyone. If you consume some higher-mercury fish, be sure to have only lower mercury types for a few weeks afterward. Check state and local fish advisories first if you're considering eating fish caught by somebody you know, the EPA recommends.

Look beyond the fresh fish counter. You can buy fish in cans or pouches rather than (or in addition to) fresh fish. Canned fish, such as salmon, sardines, and light tuna, is easier to store than fresh and could be used in salads, sandwiches, and other dishes, says Majumdar, who makes patties with canned salmon, onion, and diced pepper. Frozen fillets are another convenient way to keep fish on hand.

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4 Brain-Healthy Fish Dishes
Researchers found that people who ate fish at least twice a week were less likely to have signs of blood vessel damage than those who didn’t consume fish. These recipes will help you heed the researchers’ advice to eat more fish.