According to recent research, the variety of helpful microorganisms in our mouths varies significantly based on different lifestyles, such as those of nomadic hunter-gatherers, farmers, and industrialized communities.
A study led by Penn State biologists suggests that an individual’s lifestyle can significantly influence the makeup of beneficial bacteria and other microorganisms present in the mouth. This international research team discovered variations in the “oral microbiome,” which refers to the community of microorganisms in our mouths, across various subsistence strategies, moving from nomadic hunter-gatherers to farmers and then to industrialized populations. The findings, detailed in a paper published on November 4 in the journal Microbiome, also indicated that specific lifestyle factors, including smoking, can further influence this microbiome.
A balanced oral microbiome is crucial as it assists in food digestion, bolsters the immune system, and guards against harmful pathogens. Conversely, a disrupted oral microbiome has been linked to numerous health issues in humans.
“The oral microbiome has not received adequate attention, with most studies conducted in Western populations,” explained Emily Davenport, an assistant professor of biology at Penn State and leader of this research. “While we’ve gained significant insights from these studies, microbiomes vary globally. By exploring how lifestyle diversity influences the oral microbiome worldwide, we can enhance our understanding of its effects on human health.”
The study examined 63 individuals from Nepal, showcasing a broad array of dietary habits. Researchers investigated how significant lifestyle elements, particularly subsistence strategies — the methods by which people secure food and shelter — as well as more specific behaviors like smoking, may contribute to the differences seen in the microbiomes across different groups.
“Prior studies indicated microbiome differences between people in highly industrialized societies and those who are nomadic hunter-gatherers. However, there lies a wide spectrum of lifestyles between these extremes,” noted Erica Ryu, a biology graduate student at Penn State and the first author of the paper. “Our understanding of these lifestyle impacts has often been complicated by geographical factors, making it challenging to generalize findings when comparing individuals from different countries with varying climates, healthcare access, and exposure to different diseases. Our study provides a detailed examination of oral microbiomes from a variety of lifestyles within the same nation, Nepal.”
The researchers investigated the oral microbiomes of participants from diverse subsistence strategies, including foragers (nomadic hunters and gatherers), subsistence farmers (recently settled hunter-gatherers), long-established agriculturalists, and industrialized groups (Nepalese who immigrated to the United States in the past 20 years). They also posed questions regarding various lifestyle factors such as diet, education, medical practices, and different behaviors.
The team sequenced the DNA from saliva samples to identify specific bacterial species in each person’s oral microbiome. They found that the species composition aligned with the subsistence strategies in a gradient, noting the presence of certain species in foragers and one particular species in industrialized groups, indicating a lifestyle impact on the oral microbiome.
Furthermore, several microbial species were linked to specific lifestyle choices, such as smoking habits, the primary grains in one’s diet (barley and maize versus rice and wheat), and the consumption of a plant called nettle. Previous studies have noted a consistent relationship between smoking and oral microbiome composition in industrialized populations, suggesting that smoking significantly influences the oral microbiome across various lifestyles.
“It’s logical that different microbes could thrive on distinct grains in someone’s diet, but it’s intriguing to find a correlation with sisnu, or nettle,” remarked Davenport. “Nettle is a fibrous plant commonly chewed by foragers in our study, somewhat akin to chewing gum. Given its cultural and culinary importance in Nepal, its association with oral microbes is noteworthy.”
The researchers emphasized the need to consider lifestyle factors in future microbiome studies and to include diverse populations from around the globe.
“We focused on populations in Nepal because it allowed us to examine lifestyle effects while managing various other variables like geography that could obscure these effects,” stated Davenport. “However, this underscores lifestyle factors likely influencing other populations as well.”
“Any shift — whether it’s in diet, location, or culture — can alter the microbiome, and we must understand the degree and speed of these changes,” she added. “Continuing to explore how oral microbiomes differ worldwide will enhance our comprehension of what influences them and their effects on human health.”
The research team also included Meera Gupta, a former undergraduate student, alongside collaborators from New York University, Abu Dhabi; the University of Texas Health Science Center at Houston; and various institutions in Nepal. Funding for this work came from the National Institutes of Health, Stanford University, and New York University Abu Dhabi.
