Although overall health and life expectancy are high in the Westernized societies, could aspects of the Western lifestyle have a negative impact on gut bacteria?
In the study, published in Cell Reports, researchers analyzed the gut bacteria of residents of the US and Papua New Guinea, one of the least urbanized countries in the world, in order to assess the effects of the Western lifestyle.
"There are several aspects of Western lifestyle that have been hypothesized to alter the gut microbiome and decrease diversity," says senior author Jens Walter, of the University of Alberta in Canada. "These include diet, sanitation, and clinical practices such as antibiotic use and cesarean sections, but we lack a conceptual understanding of how our microbiomes are altered."
Gut bacteria impact on both physiology and health. According to the study authors, recent studies indicate that the gut microbiome makes a crucial contribution to the way the body reacts to noncommunicable diseases prevalent in Westernized societies, such as inflammatory bowel disease, allergies, colon cancer and autoimmune diseases, including multiple sclerosis and type 1 diabetes.
Scientists have previously hypothesized that an irregular microbiome can increase the risk of these diseases for Westerners. Conversely, gut bacteria are also important for protecting against infectious diseases such as diarrhea in nonindustrialized communities, therefore warranting a comparison of the microbiome in both settings.
"The majority of Papua New Guineans live a traditional, subsistence agriculture-based lifestyle," write the authors of the study. "[Papua New Guinea] has poor general health and socioeconomic predictors: infant and maternal mortality rates are high and the life expectancy is low."
In Papua New Guinea, leading causes of death include infectious diseases such as pneumonia, malaria, tuberculosis and diarrhea. Conversely, noncommunicable diseases such as multiple sclerosis and type 1 diabetes are rarely reported.
Around 50 bacterial types in Papua New Guinean microbiomes missing from US residents
For the study, the researchers analyzed the fecal bacteria of a total of 40 participants from two different societies in Papua New Guinea. These participants lived in traditional settings with no sewage facilities, wastewater or drinking water treatment. Their fecal bacteria were compared with fecal samples taken from 22 participants residing in Lincoln, NE.
The researchers found that the microbiomes of the Papua New Guinean participants had a greater bacterial diversity, lower individual variation and different compositional profiles in comparison with the microbiomes of the US residents.
Approximately 50 bacterial types were absent in the gut microbiomes of the US residents that were part of the core Papua New Guinean microbiome.
The researchers noted that there were differences between the two societies in the relative importance of ecological processes that shape the gut microbiota. In the Papua New Guinea residents, the ability of bacteria to move from person to person - bacterial dispersal - was the most important process in structuring the microbiota.
"These findings suggest that lifestyle practices that reduce bacterial dispersal - specifically sanitation and drinking water treatment - might be an important cause of microbiome alterations," states Walter. "We propose a model based on ecological theory that fits the data and provides an explanation for the decline of microbiota diversity in urban-industrialized societies."
The researchers state that readers should be cautious of questioning Western lifestyle practices straight away, as life expectancy and overall health remains much higher in Westernized societies.
"However, we can think about how we can reduce the collateral damage of modern lifestyle practices on the gut microbiome without jeopardizing the benefits," suggests co-author Andrew Greenhill, from Federation University Australia.
"The findings from this study provide information that could be used to develop strategies to prevent and redress the impact of Westernization and potentially support the dispersal and transmission of microbes that have been eradicated."
A question for additional research to address is how specific lifestyle and cultural factors affect the altering of microbiomes. The role of the 50 bacterial types absent from the Western microbiomes is another path of investigation.
"Such research might provide important information on the causes of Western lifestyle diseases and a basis for the development of therapies for their treatment and/or prevention," concludes Walter.
To learn more about the role of the gut microbiome, a Medical News Today Spotlight feature published last month takes a look at how the thousands of bacteria in the gut can influence health.