Fish Consumption Protects Brain from Toxic Effects of Air Pollution

Highlights

• Lower levels of omega-3 fatty acids in the blood lead to brain shrinkage
• Older women exposed to fine particulate matter pollutants experience shrinkage of brain matter, especially if they have low levels of omega-3 fatty acids in their blood
• Consumption of broiled, baked, or canned fish, rich in omega-3 fatty acids, help to counteract the effect of air pollution

Consuming one or two servings of baked, or broiled fish or shellfish in a week, helps to counteract the effect of air pollution in older women, because fish is an abundant source of omega-3 fatty acids. The fine particulate matter found in pollutants is a neurotoxin and damages the brain on long-term exposure. Neurotoxins damage the peripheral nervous system or brain by disrupting or damaging the nerves.// The nerve cells called neurons are affected the most by neurotoxins. The body’s response to neurotoxins depends on the neurotransmitter affected, integrity of cellular membrane, and the presence of detoxifying mechanisms.

Fish is a rich source of omega-3 fatty acids. Omega-3 fatty acids are beneficial for brain health. It fights inflammation and preserves the brain structure in the aging brain. It also reduces the brain damage caused by neurotoxins such as lead and mercury.

The new study is published in the online issue of Neurology®, the medical journal of the American Academy of Neurology.

The research found that among older women with lowest levels of omega-3 fatty acids in their blood, living in areas with high air pollution levels, had more brain shrinkage than women who had t highest levels of omega-3 fatty acids.

“Fish are an excellent source of omega-3 fatty acids and easy to add to the diet,” said study author Ka He, M.D., Sc.D., of Columbia University in New York. “Omega-3 fatty acids have been shown to fight inflammation and maintain brain structure in aging brains. They have also been found to reduce brain damage caused by neurotoxins like lead and mercury. So we explored if omega-3 fatty acids have a protective effect against another neurotoxin, the fine particulate matter found in air pollution.”

Study

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For the study, 1,315 women with an average age of 70 years, had participated. They did not have dementia at the start of the study. The women completed questionnaires about diet, physical activity, and medical history.

The diet questionnaire helped to determine the average fish consumption of each woman per week. This included broiled or baked fish, canned tuna, tuna salad, tuna casserole and non-fried shellfish. Fried fish was not included since deep frying damages omega-3 fatty acids.

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Blood tests were conducted on the participants to determine the amount of omega-3 fatty acids in the red blood cells. The women were divided into four groups depending on the amount of omega-3 fatty acids in their blood.

The exposure to air-pollutants was determined over a period of three years. Participants underwent brain scans with magnetic resonance imaging (MRI), to measure areas of the brain including white matter, composed of nerve fibers that send signals throughout the brain, and the hippocampus, that is associated with memory.

Results

Results were calculated after adjusting for confounding factors like age, education, smoking and others that could affect brain shrinkage.

Results showed that women who had the highest levels of omega-3 fatty acids in the blood had greater volumes of white matter, 410 cubic centimeters (cm3), and those with the lowest of omega-3 fatty acid levels had 403 cm3 of white matter. Volume of the hippocampus was also higher in the group with highest levels of omega-3 fatty acids.

The average white matter volume was 11.52 cm3 smaller among people with lower levels of omega-3 fatty acids, and 0.12 cm3 smaller among those with higher levels, for each quartile increase in air pollution.

“Our findings suggest that higher levels of omega-3 fatty acids in the blood from fish consumption may preserve brain volume as women age and possibly protect against the potential toxic effects of air pollution,” said He. “It’s important to note that our study only found an association between brain volume and eating fish. It does not prove that eating fish preserves brain volume. And since separate studies have found some species of fish may contain environmental toxins, it’s important to talk to a doctor about what types of fish to eat before adding more fish to your diet.”

Limitations

A major limitation of the study was that most participants were older white women. Hence the results cannot be generalized. Only the exposure to later-life pollution could be assessed while the early or mid-life exposures, could not be assessed.

Future studies should look at exposures to air pollution across a person’s lifespan.

Source-Medindia