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Oily fish such as salmon, sardines and lake trout, as well as some plant sources such as nuts and flaxseeds, can be good tasty sources of omega-3 fatty acids.
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MinoruM / Getty Images
Oily fish such as salmon, sardines and lake trout, as well as some plant sources such as nuts and flaxseeds, can be good tasty sources of omega-3 fatty acids.
MinoruM / Getty Images
It has long been known that air pollution influences the risk – and severity – of asthma. More and more evidence shows that food can also play a role.
A new study reveals that an increased consumption of omega-3 fatty acids, found in oily fish such as salmon, sardines and lake trout and in some plant sources such as nuts and flax seeds, is related to a reduction in asthma symptoms in children in cities exposed to fairly high levels of indoor air pollution.
"We know that asthma is a disease caused by inflammation," says Dr. Emily Brigham, a pulmonologist at Johns Hopkins University and co-author of the study. As our body digests fish, omega-3 fatty acids generate byproduct molecules called "pro-resolving mediators" that enter our lungs. "They help to solve the inflammation," says Brigham.
Given this anti-inflammatory effect, Brigham and his colleagues felt that diets rich in omega-3 fatty acids may help mitigate the effects of air pollution on children's symptoms. To study this, they followed dietary patterns and indoor air pollution levels (from sources such as smoke, dust, and allergens) in 135 children, mostly African-Americans and suffering from high blood pressure. Asthma in Baltimore, Maryland.
They measured two types of indoor air pollution, consisting of different particle sizes: PM2.5 (fine respirable particles 2.5 microns or less) and slightly larger PM10s. These particles are too small for us to see, but they can enter our airways and the smaller size – PM2.5 – can lodge deep in our lungs.
"What we found was that higher omega-3 consumption would have been associated with reduced effects of suspended particles on symptoms inside buildings. "said Brigham. "Children who ate more omega-3s seemed to better withstand the effects of particles."
Brigham and his team also evaluated the intake of omega-6 fatty acids found in vegetable oils and in abundance in many processed foods containing oil. In general, Americans consume far more omega-6 than omega-3s, which was also the case for all children in the Baltimore study. The study also found that children who consumed the most omega-6 fatty acids had more serious asthma symptoms.
Brigham says that the role of omega 6 fatty acids in inflammation is complicated. Some of the by-products of omega-6 acids, such as leukotrienes, have been shown to be pro-inflammatory. "Leukotrienes are one of the molecules known to be responsible for inflammation related to asthma," she said.
As this was an observational study, researchers can not prove that omega-3 acids caused a decrease in symptoms nor that the high consumption of omega-6 acids caused more serious symptoms. But the results are consistent with the many evidence documenting the anti-inflammatory effects of omega-3s.
And, in terms of mitigating the effects of air pollution, other studies support the idea that dietary interventions can help to provide protection.
"This study adds to an increasing number of publications suggesting that food, western, Mediterranean, etc. – can influence the health effects of air pollution exposure," he said. said Kym Gowdy, assistant professor of pharmacology and toxicology at East Carolina University.
She cites a recent study published in the journal circulation a Mediterranean diet has reduced the risk of death from cardiovascular disease due to prolonged exposure to air pollutants.
"The [new] Dr. Brigham's study confirms the general idea that nutritional status is an important factor to consider in enhancing protection against air pollution, "says Neil Alexis, a professor at Chapel's UNC School of Medicine. Hill, NC
And although Brigham's study focuses on fatty acids useful in foods, Alexis notes that another study found that antioxidant supplements can help mitigate the impact of exposure to ozone on the small airways of children with moderate to severe asthma. At the same time, a separate study conducted in 2018 in adults revealed that vitamin E helped to reduce the inflammatory characteristics of asthma.
In general, a diet rich in fruits, vegetables, nuts and seeds and healthy fats – including omega-3 – has many health benefits, including a reduced risk of cardiovascular disease. The new study highlights another potential benefit, especially for people exposed to air pollution. And when it comes to getting enough omega-3 fatty acids: The American diet recommendations recommend that adults consume 8 ounces of seafood a week and younger children a little less.
