Eating one or two servings of fish a week may protect older women from brain-damaging effects of air pollution
Consuming a plate or two of grilled, baked fish every week may help shield older women from the brain-damaging effects of air pollution, suggests a new study. Fish oils, which contain omega-3 fatty acids, could be driving these benefits, according to scientists.
Researchers from Columbia University in New York found that older women, who resided in regions with high pollution levels and consumed fish, had higher omega-3 acids in their blood. They also had greater brain volume, a sign that the brain is healthy.
Brain volume shrinks with age, and this decline results in impaired mental abilities. "Once lost, brain tissue cannot be recovered. A slower rate of brain volume loss may help prevent Alzheimer’s disease and other neurodegenerative diseases," Dr Cheng Chen, the first author of the study from the Columbia University Irving Medical Center, told MEA WorldWide (MEAWW).
The researchers speculated that omega-3 acids could be preserving brain volume. "Since environmental pollution is unavoidable, these findings provide helpful insight regarding how a healthy diet could reduce the adverse effects of air pollution on cognitive decline and neurodegeneration," she added.
Air pollution and the brain
Air pollution particles make their way into the brain and induced damage. Of specific risk is particulate matter 2.5 (PM 2.5), pollutants which measure about two and a half micrometers in width. For comparison, the average human hair is about 70 micrometers in diameter. These particles float in the air and can be hazardous when inhaled. They can reach the lungs and cause short-term health effects such as irritation in the eye, nose, throat, and lung, coughing, sneezing, runny nose, and shortness of breath. They aggravate medical conditions such as asthma and heart disease and, more recently, Covid-19.
These pollutants also lead to inflammation in the brain. Omega-3 fatty acids possibly act by reducing the inflammation. Other explanations include their role in protecting cells responsible for producing and maintaining myelin, a fatty substance that ensures that our nerve fibers do their job. They also facilitate repair in the white matter -- a part of the brain involved in learning, thinking, to name a few.
"In previous studies, fish oil reduced the brain damage caused by exposures to various environmental neurotoxins, including lead, organic solvents, and methyl mercury. PM2.5 exposure is a risk factor for cognitive decline and reduced brain volumes. But no study has examined whether fish oil offers similar protection against PM2.5 exposure," Dr Cheng explained.
What did the study find?
They investigated whether omega 3 fatty acids protect people from PM 2.5. They studied 1,315 women, with an average age of 70, and collected comprehensive data on omega-3 fatty acid levels in the blood, PM2.5 exposure, and MRI scans of the brain.
The participants were asked to fill out questionnaires, which captured their fish intake patterns. They did not consider fried fish as this mode of cooking damages omega-3 fatty acids. They also collected blood samples to measure the levels of the nutrient.
The team then collected the residential address of the participants to measure their three-year average exposure to air pollution. To peek into the brain, the researchers deployed magnetic resonance imaging (MRI) and measured brain volume.
Comparing the data from MRI, blood tests, and air pollution exposure, the researchers observed that women with high omega-3 fatty acids in the blood had a higher brain volume in the white matter: 410 cubic centimeters while those with low circulating levels of the nutrient had 403 cm3.
What is more, women with high omega-3 fatty acids in the blood also had a greater volume of the hippocampus, part of the brain associated with memory. Dr Cheng added that future studies should dig deeper to gain a clear picture of how omega-3 fatty acids lower the brain damages induced by the pollutant.
Should you eat fish?
"Fish is an excellent source of omega-3 fatty acids and easy to add to the diet," says study author Dr Ka He. Some examples include salmon, mackerel, tuna, herring, and sardines. Vegetarians can get their dose of the nutrient from nuts, seeds, plant oils, certain brands of eggs, yogurt, milk, soy beverages, and infant formulas, according to the National Institutes of Health.
Dr He, however, said that their study only showed a link between brain volume and eating fish, adding that it did not prove that it is protective. He also encouraged people to consult their doctor before turning to seafood, given that some species may contain environmental toxins.
The study was published in the American Academy of Neurology.