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Air pollution may be bad for your gut microbiome

 A hazy view of the Flatirons from South Boulder Road in Boulder, Colorado.
Shannon Young
A hazy view of the Flatirons from South Boulder Road in Boulder, Colorado.

The Environmental Protection Agency has issued a final determination to downgrade air quality in the Denver Metro and Northern Front Range area to “severe” non-attainment for ground-level ozone.

The effects of poor air quality on cardio-respiratory health are well documented, but recent studies show bad air may also affect the gut microbiome in people as young as infants.

One of the leading scientists studying the link between air quality and gut health is Tanya Alderete, assistant professor of Integrative Physiology at CU Boulder.

She says inhaled pollutants may affect the gut microbiome in various age groups, including babies.

"We can inhale air pollution, particulate matter that's in our environment. And these particulate matter can reach our gut through inhalation and diffusion from our lungs, where then once in the gut, it can impact gut bacterial communities, which is what we hypothesize is happening," said Alderete.

"So it might, for example, disrupt some bacterial communities, making it less of a hospitable environment for them to live in, or it might actually make it a better environment for certain bacteria to grow. So this is an area we're just beginning to understand," she said.

Alderete says the gut microbiome is a community of bacteria that plays a significant role in our overall health.

"Bacteria can help with our immune system development, help control inflammation, or contribute to increased inflammation. And it's been linked with many health outcomes like obesity, type 2 diabetes, neurodevelopment," she said.

Alderete conducted a small pilot study on around 50 young adults from Southern California that looked at any association between air pollution exposure and bacteria in their gut.

"And so we found that near roadways, air pollution exposure was associated with specific bacterial taxa that have been linked with obesity and type 2 diabetes. So to my knowledge, that was the first study, specifically looking at air pollution and gut bacteria. Since then there have been a few other studies looking at air pollution and the gut microbiome, and one study has found that bacteria in the gut may mediate the associations between air pollution and risk factors for type 2 diabetes, which was really interesting," said Alderete.

Alderete recently studied the connection between environmental exposures, such as air pollution, and infant health.

The infants' mothers who were recruited into the study agreed to breastfeed for an extended period of time. They were healthy but had a range of body mass index.

"Now their particular characteristics didn't make me any more or less surprised regarding the associations that we observed and their babies at six months of age, and I think that's because we had already seen associations and young adults that were also relatively healthy as well with a range of body mass index. So I guess since we know the microbiome is developing in early life and there's just not a lot of bacteria early on because it's in the process of becoming populated with gut bacteria," said Alderete.

"That was one factor that made me a little bit more surprised that we saw association so early because it wasn't like it was as diverse of a gut microbiome as we see in adulthood. But I think pretty much what we found is that these associations exist early in life and are consistent with some of the findings we saw in young adults."

Alderete says a future area of investigation would be looking at babies who are formula fed.

"So this is something we intend to look at down the road. Is it potentially that those infants that are breasted and breastfed longer might not show the same associations that we see with air pollution as infants that were not breastfed or breasted for a shorter period of time. And this is something that I would hypothesize to be true, given that we know breast milk is an important pre and probiotic for the developing infant microbiome. So when I get asked, 'what is it exactly that we can do to help offset some of the potentially negative effects of environmental exposure on the developing microbiome?' I think a smart move to do would be to continue to breastfeed as long as possible."

While there are many things regarding air quality outside of our control, like high ozone and particulates in the air, Alderete says there are things that can be done to our own personal environment that can help mitigate or decrease our exposure to bad air quality.

"And that can be simple things like looking at the air quality index before you go outside to exercise. So you try to pick times of the day also around, let's say commuter traffic, where you might get lower exposures. I think with COVID, we've all come to appreciate the importance of indoor air quality as well. So purchasing low cost air filtration systems for your home, that you can place in your room while you're sleeping at night could be a great way to also decrease exposures. And then there's things just like opening your windows. If you're going to be cooking, avoiding secondhand smoke exposure. All of these are complex mixtures of inhaled pollutants that we know can have harmful effects on our health," she said.

This story from KGNUwas shared with us via Rocky Mountain Community Radio, a network of public media stations including KDNK in Colorado, Wyoming, Utah and New Mexico.

Young is a longtime independent journalist, with a vast history in editorial and production leadership. She has been working in Mexico as a foreign correspondent and regularly contributed to PRX’s “The World,” Public Radio International, the Canadian Broadcasting Corporation (CBC), The Guardian, Vice News, Truthout, and the Texas Observer.