City Dwellers May Have Bad Breath Due To The Pollutants, Stress, And Dietary Habits Associated With Urban Life

nenetus
nenetus - stock.adobe.com - illustrative purposes only, not the actual person - pictured above a young woman walks across a city street while holding coffee and a phone

Urban living could be preventing city dwellers from having minty, fresh breath, all thanks to unique pollutants, stress, and dietary habits linked to city life.

A team of biologists has figured out how the microbes in our mouths are connected to the ways we live our lives.

These microbes influence how our immune systems battle infections, how we digest our food and even the smell of our breath.

The scientists analyzed the saliva of 63 individuals from Nepal, looking into the differences in oral microbiomes in hunter-gatherers, foragers, farmers, and people living in urban environments. They also considered factors such as diet and smoking.

According to Emily Davenport, the leader of the study and an assistant professor from Penn State Eberly College of Science, the oral microbiome has been understudied. In addition, most of those studies were conducted in Western populations.

“Although we have learned a lot from that, microbiomes look different around the world. By studying how the diversity and composition of the oral microbiome varies with lifestyle in a global context, we can improve our knowledge of how the oral microbiome impacts human health,” Davenport said.

The biologists examined the microbiomes in the mouths of five different categories of people. The first was the Chepang people, who are foragers in Nepal. Next were the Raji and Raute groups, who were hunters and gatherers that had recently settled and begun farming.

Then, there were the Tharu and Newars people, who had relied on farming for over 300 years, and Nepalis, who had moved to the United States within the past 20 years. Finally, the researchers analyzed a group of Americans of European descent for comparison.

They found that the differences in oral microbiomes between the groups were relatively subtle. However, there were a few changes in the compositions of some microbes that supported the idea that lifestyle plays a role in oral microbiomes.

nenetus – stock.adobe.com – illustrative purposes only, not the actual person – pictured above a young woman walks across a city street while holding coffee and a phone

In urban groups, one strain that saw a significant increase was Abopobium, high levels of which are associated with tooth decay.

Other lifestyle factors that appeared to contribute to the composition of mouth microbiomes were smoking and fiber and carbohydrate intake.

The team detected a notable difference between groups that ate the majority of their carbohydrates from maize and barley and those who ate more rice and wheat.

Consumption of maize and barley was related to better oral microbiome health, as there is more fiber and less quickly digested starch.

Rice and wheat led to increased levels of salivary amylase, an enzyme that starts to digest starches in the mouth.

Differences were also observed depending on whether the study participants chewed nettle, also known as sisnu.

“Nettle is a fibrous plant often chewed by the foragers in this study, much like people might chew gum. Given its important role in Nepali cuisine, culture, and medicine, it’s interesting to see it is associated with oral microbes,” said Davenport.

Continued investigations of mouth microbiomes can help scientists improve their understanding of how they impact human health. The study was published in the journal Microbiome.

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