Mouth microbes reflect your lifestyle choices

A recent study has shown how lifestyle factors influence the composition of the oral microbiome – the community of beneficial bacteria and other microbes living in the mouth. 

This research, which spans different subsistence lifestyles, from nomadic hunter-gatherers to industrialized groups, reveals how both broad lifestyle patterns and specific habits like smoking shape the oral microbiome. 

Diversity of the oral microbiome

The oral microbiome plays a key role in human health, aiding in digestion, bolstering immune function, and guarding against pathogens. However, a shift in its balance can be linked to various health issues. 

“The oral microbiome has been understudied, and most studies of the oral microbiome have been conducted in Western populations,” said Emily Davenport, an assistant professor of biology at Penn State and leader of the research team. 

Davenport explained that the diversity and composition of the microbiome vary globally, and by examining it within different lifestyles, the team hopes to expand understanding of its impact on health across different populations.

Mouth microbes and diverse lifestyles

To understand how lifestyles affect the oral microbiome, the team conducted a study on 63 individuals in Nepal, a region that offered diverse subsistence strategies within the same geographic area. 

This approach allowed researchers to assess how lifestyle influences the microbiome without the confounding effects of geographical differences like climate, disease exposure, and access to healthcare. 

“In this study, we comprehensively investigated the oral microbiome of individuals across a range of lifestyles from the same country, Nepal,” explained Erica Ryu, the study’s first author and a graduate student at Penn State.

The participants represented a range of subsistence strategies: hunter-gatherers who move throughout the year, subsistence farmers who recently settled and started farming, agriculturalists with a longstanding history of farming, and both Nepali and American industrialists from highly industrialized settings. 

The researchers also collected detailed lifestyle information, including diet, educational background, medical practices, and habits.

Clear impact of lifestyle on mouth microbes 

Using DNA sequencing on saliva samples, the team identified the specific bacteria present within each person’s oral microbiome. 

The researchers found that bacterial species composition closely followed a gradient that matched the subsistence strategies, with distinct species more common among foragers and other species more common among industrialized individuals. 

This suggests a clear impact of lifestyle on the microbiome, supporting the hypothesis that lifestyle influences which microbial species thrive.

Some of these lifestyle-related microbial species were linked to particular behaviors, such as smoking, diet, and specific plants in the diet, like nettle, which is commonly chewed in Nepali culture. 

The findings underscore that lifestyle extends beyond just environmental context to include unique cultural and habitual factors that affect the microbiome.

Diet and culture shape the microbiome

The researchers found significant associations between certain microbes and dietary staples. For instance, individuals who primarily consumed barley and maize had distinct microbiome profiles compared to those who primarily consumed rice and wheat. 

This reflects the idea that certain microbes may thrive depending on the grains in a person’s diet. 

“It makes sense that different microbes might feed on the different grains in a person’s diet,” said Davenport, emphasizing the connection between dietary components and microbial composition. 

The team also noted an association with nettle, a fibrous plant often chewed in Nepal. 

“Nettle is a fibrous plant often chewed by the foragers in this study, much like people might chew gum,” Davenport explained, adding that its presence in the diet could contribute to the unique microbiome composition observed in Nepali foragers.

The role of smoking

The study highlights smoking as another significant factor influencing the oral microbiome. 

Past research has shown that smoking affects the microbiome in industrialized populations, and the current study extends this finding across varied lifestyles. 

The consistent association between smoking and microbiome composition suggests that certain lifestyle factors play a key role regardless of broader lifestyle patterns or geography.

Future research directions

The research team stresses the importance of considering lifestyle factors and cultural behaviors in future microbiome research. 

The experts also advocate for the inclusion of diverse populations to achieve a more comprehensive understanding of the oral microbiome’s role in health. 

“We studied populations in Nepal because it offered a unique way to explore the effects of lifestyle while controlling for a variety of other factors like geography that often obscure that effect,” Davenport said. 

This approach reveals the impact of lifestyle on microbiome health, which is likely relevant for other populations as well.

“Whenever you make a shift – whether it’s to a different diet or different location or different culture – the microbiome can change too,” Davenport emphasized. 

By investigating how microbiomes vary globally, scientists can better understand the processes that shape the microbiome and how these variations affect human health. This knowledge could lead to improved strategies for managing health outcomes and preventing diseases linked to microbiome imbalances.

The study marks a significant step forward in understanding how the oral microbiome adapts to diverse lifestyles, offering new insights that could inform future healthcare and conservation efforts around the world.

The findings are published in the journal Microbiome.

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