High levels of air pollution during the first six months of life could affect the colonies of bacteria in babies' guts, increasing their risk for allergies, obesity, diabetes and issues with brain development, according to new research.
Researchers said their new study is the first to show a link between inhaled pollutants from traffic, wildfires, industry and other sources with changes in babies' gut bacteria, or microbiome.
"This study adds to the growing body of literature showing that air pollution exposure, even during infancy, may alter the gut microbiome, with important implications for growth and development," said senior author Tanya Alderete. She's an assistant professor of integrative physiology at the University of Colorado Boulder.
Her team used genetic sequencing to analyze stool samples from 103 babies enrolled in the Southern California Mother's Milk Study. The babies were primarily breast-fed, healthy Latino infants.
The investigators also used street addresses and U.S. federal government air quality data to estimate infants' exposure to fine particle pollutants PM2.5 and PM10, and nitrogen dioxide, a gas largely emitted from cars.
Infants who were exposed to higher levels of air pollution had more bacteria in their guts associated with inflammation, which boosts the risk of disease.
Babies are born with little gut bacteria, the researchers said. Those that will influence appetite, insulin sensitivity, immunity, mood, thinking and even chronic illness can take hold in the first few years of life, and they are affected by the environment.
"Overall, we saw that ambient air pollution exposure was associated with a more inflammatory gut-microbial profile, which may contribute to a whole host of future adverse health outcomes," Alderete said in a university news release. The study found associations, but not a cause-and-effect link.
The researchers found that infants with the highest exposure to PM2.5 had 60% less of a beneficial bacterium called Phascolarctobacterium. It is known to decrease inflammation, support gastrointestinal health and aid in brain development.
Meanwhile, babies with the highest exposure to PM10 had 85% more of the microorganism Dialister. It, too, is associated with inflammation.
Researchers noted that these issues may have a greater effect on racial minorities and low-income communities. These residents tend to work, live and attend school in areas with more pollution -- for example, near busy highways or factories. Communities of color are exposed to 1.5 times more airborne pollutants than white communities, according to a 2018 U.S. Environmental Protection Agency study.
"Our findings highlight the importance of addressing the impact of pollution on disadvantaged communities and point to additional steps all families can take to protect their health," Alderete said.
To reduce the impact of indoor and outdoor pollution, she suggested several steps: Avoid walking outdoors in high traffic zones. When cooking, keep windows open. Consider buying a low-cost air-filtration system, especially for rooms where children spend a lot of time. New moms can potentially help offset the impact of environment by breastfeeding for as long as possible.
The findings were recently published in the journal Gut Microbes.
The U.S. Environmental Protection Agency has more on PM 2.5.
SOURCE: University of Colorado Boulder, news release, Sept. 1, 2022