The microbes inside you can be influenced by the people around you.
A large and diverse review of the evidence has revealed that your microbiome could be affected more by who you live and with whom you were raised than any lifestyle factors, genetics, or age.
The findings suggest that trillions more microbes could be contagious to our bodies than we think. That could have serious consequences for public health.
Nicola Segata, a microbiologist from the University of Trento (Italy), has conducted research that does not show how microbes jump directly from one person to the next. However, it shows how much of our gut- and mouth bacteria is shared by those around us.
Social interactions, the authors conclude, could help shape an individual’s community of microbes, and that, in turn, could “have a role in microbiome-associated diseases”.
These findings were based on over 9,000 stool samples and saliva samples from participants who have known connections to one another. These communities were collected from more than 9,000 people in 20 countries, including those in developing and western nations.
These findings strongly suggest that trillions of symbiotic cell in our bodies can spread among human hosts even after brief encounters in public.
Researchers found that the bacteria strains shared by participants in the study was ‘extensive. Researchers discovered more than 10,000,000 instances where bacteria was shared between mothers, infants, members in the same household or people living together.
Research has shown that mother’s help in boosting the microbiome of their children within the first months of life is by sharing her microflora with them. This can be done through breastfeeding, vaginal birth, touch, salivary exchange and breastfeeding.
It is also well-known that the microbiome of a person can change throughout their lives depending on how they eat, exercise, and where they live.
Human to human transmission has not been extensively studied. According to the results of this review, it is possible that there has been an oversight.
Mother-to-infant transmission was, as expected, the most important route of exposure. In 711 cases about 50% of the same bacterial strains were found in mother-to-child transmission. Additionally, 16 percent of those strains had originated from the mother.
This seeded community could be found even later in life, though at lower levels. For example, at 30 years old, the average participant in the study had retained about 14 percent their mother’s original bacteria strains. Even after 85 years, the most transmissible strains of a mother were still present in her offspring.
As an individual ages, their mother’s microbial influence becomes more balanced by other relationships. The microbiome makeup of a person’s microbiome is affected by who they live with and how they interact with them on a daily basis.
Researchers found that children have equal amounts of bacteria from their father and mother after the age of four. Furthermore, researchers found that identical twins who lived apart for longer periods of time had fewer microbial strains in their gut.
The majority of bacteria strains found in the mouth and gut are shared by around 12 to 32 per cent. These results were not explained by similar lifestyle factors.
Segata says, “In adulthood the sources of our microbiomes is mostly the people we’re in close contact with.”
“The duration of interactions – think for example of students or partners sharing an apartment – is roughly proportional to the number of bacteria exchanged.”
They noticed a close, but smaller relationship when the authors looked into larger communities.
It was rare for bacterial strains to cross between rural communities. The transmissibility of bacterial strains to rural communities was high across all datasets.
In 67 percent of the communities that were studied, people from the same village and different households shared more bacteria strains than those living in other villages.
Even the most casual interactions can impact a person’s microbiome. Some microbes may have health benefits while others can make people more susceptible to disease or illness.
Segata says that the transmission of microbiome can have important implications for our health. Some non-communicable diseases such as cancer, diabetes, and cardiovascular disease, are partially linked to altered microbiome compositions.
“The evidence that the human microbiome can be transmitted could indicate that some of these conditions, currently considered non-communicable, could, at most, be communicable.”
The study was published in Nature.
