Study: Exposure to air pollution in infancy increases risk of obesity, diabetes; best counter is breast milk

In infants, air pollution alters structure and function of human gut microbiome — the trillions of micro-organisms living within us.

BySumit Jha

Published Sep 07, 2022 | 8:00 AM Updated Sep 07, 2022 | 8:00 AM

Air Pollution

Exposure to air pollution in the first six months of life impacts the inner world of gut bacteria, or microbiome, in ways that could increase risk of allergies, obesity and diabetes in later life, and even influence brain development, suggests a new study.

The study, published in the journal Gut Microbes, is the first to show a link between inhaled pollutants — such as those from traffic, wildfires and industry — and changes in infant microbial health during this critical window of development.

Air pollution causes changes in the structure and function of the human gut microbiome — the collection of trillions of microorganisms residing within us.

The study, by researchers from the Department of Integrative Physiology at the University of Colorado at Boulder, reveals that at birth, an infant hosts little resident bacteria. Over the first two to three years of life, exposure to mother’s milk, solid food, antibiotics and other environmental influences shape which micro-organisms take hold.

How it impacts appetite & insulin sensitivity

Those microbes, and the metabolites, or byproducts, they produce when they break down food or chemicals in the gut, influence a host of bodily systems that shape appetite, insulin sensitivity, immunity, mood and cognition.

“While many are beneficial, some microbiome compositions have been associated with Chrohn’s disease, asthma, type 2 diabetes, and other chronic illnesses,” reads the study.

“The microbiome plays a role in nearly every physiological process in the body, and the environment that develops in those first few years of life sticks with you,” said the study’s lead author Maximilian Bailey.

Causing inflammation

For the study, the researchers obtained faecal samples from 103 healthy, primarily breast-fed Latino infants enrolled in the Southern California Mother’s Milk Study and used genetic sequencing to analyse them.

Using their street addresses and data from the US Environmental Protection Agency’s Air Quality System, which records hourly data from monitoring systems, they estimated exposure to PM2.5 and PM10 (fine inhalable particles from factories, wildfires and construction sites) and Nitrogen Dioxide (NO2), a gas largely emitted by cars.

“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,” said co-author Tanya Alderete in a statement.

For instance, infants with the highest exposure to PM2.5 had 60 percent less Phascolarctobacterium, a beneficial bacterium known to decrease inflammation, support gastrointestinal health, and aid in neurodevelopment. Those with the highest exposure to PM10 had 85 percent more of the microorganism Dialister, which is associated with inflammation.

Infants breathe faster

Infants are particularly vulnerable to the health hazards of air pollution because they breathe faster and their gut microbiome is just taking shape.

“This makes early life a critical window where exposure to air pollution may have disproportionately deleterious health effects,” the researchers write.

Meantime, Alderete advises everyone to take these steps to reduce their exposure to both indoor and outdoor pollutants:

  • Avoid walking outdoors in high-traffic zones
  • Consider a low-cost air-filtration system, particularly for rooms children spend a lot of time in
  • If you are cooking, open the windows
  • And for new moms, breastfeed for as long as possible

“Breast milk is a fantastic way to develop a healthy microbiome and may help offset some of the adverse effects from environmental exposures,” Alderete added.