Development of Gut Microbiota

Extensive research on gut microbes has gone underway as scientists are beginning to figure out how important these microbes are to people’s health and well -being. According to Pollan, these microbes can be found all over the body, and especially in our intestines. Through various experiments, scientists have found that these microbes can possibly aid in metabolic health, immune system function, and protection against pathogens. Those and possibly other benefits of the microbial systems in our bodies are still being further researched today. Each person’s microbial community is different, based on genetics and the environment. Pollan begins to explain the reasons behind people’s individual microbial communities and describes Rob Knight’s at home studies on his own family. Scientists Chana Palmer, Elisabeth M Bik, Daniel B DiGiulio, David A Relman, and Patrick O Brown delved deeper into this question of how the communities develop and have begun to discover how certain gastrointestinal microbiota develop when humans are just infants and what factors create healthy microbial ecosystems.

In this study, the scientists tested the stool of fourteen newborn babies over the course of the babies’ first year of life. Microarray was used to analyze the stool samples. In order to further understand the development of the microbial ecosystems, vaginal swabs as well as samples of breast milk of the mothers were also tested to see how similar or different those ecosystems were to the babies’ ecosystems. The results of the study showed that there were three bacterium that were most common in the stools. The bacterial compositions of the babies in the early stages of life were very similar to the bacterial communities found in their mothers’ vaginal swabs and breast milk samples, showing how “bacterial population that develop in the initial stages is… determined by the specific bacteria to which the baby is exposed” (Palmer et al. 2007). However, each individual baby had a very different microbial ecosystem, creating an even broader definition of a healthy microbial ecosystem. Interestingly, the babies with the most similar ecosystems were the fraternal twins, possibly showing that environment can influence gut microbes. This ruled out a big genetic influence since the ecosystems of the twins were not necessarily similar to their parents, just each other. Their stool samples were compared to the mother’s vaginal swab and breast milk samples. The twins were also the only children who were delivered through cesarean section and “had lower bacterial counts (than the other babies) until their seventh day of life” (Palmer et al. 2007) which shows how there are bacterium that may not have been able to develop in those twins and they were initially at a disadvantage in having a healthy microbial ecosystem. The infants’ microbiota communities were also not much different from adult communities after just 6 months, after the introduction of adult foods to infants. Therefore, early colonization may not play a large role in the eventual adult microbiota since the same groups of bacteria are able to survive and others are not able to “stick” as well in the gut over time. Also, because the individual infants had such different microbial communities yet each community converged into an adult community, a healthy ecosystem before 6 months of age can vary greatly and all lead to similar adult ecosystems. Microbial populations that were heavily dominated by one group of bacterium, so called uneven populations, were seen mostly just a few weeks after birth and were more rarely seen later on. In many of the infants there was also at least one major change in the population structure of the microbiota communities but the changes went back to normal after even just one interval of time between testing of the stool. When antibiotic treatment was used for one infant, the density of bacteria decreased substantially. The colonization of each infant seemed to be greatly affected by the specific bacteria the baby was exposed to and the foods or medications introduced to them.

These findings differed from other studies in the past, illustrating how much is unknown about microbiota and their impact on human health, as well as their development into our bodies. Humans rely quite heavily on the functioning of our microbial system yet much about it is unknown. For example, another finding from this study, that bifidobacteria was not very abundant in the gut microbiota, differed from other researchers’ finding. According to Pollan’s article, this bacteria is very important in development and a major reason why there are oligosaccharides, complex carbohydrates, that nourish bifidobacteria in our microbial communities in breast milk. This shows how there are many different population structures in infants that can be healthy for humans.

As of now it is clear that diversity of bacteria is important to the microbial ecosystem and therefore, our health. More sterile environments, especially in the west, may be doing more harm than good to our bodies. Even babies who are born through cesarean section rather than natural childbirth are at risk of a less diverse microbial community and can be more susceptible to disease. This was both found in the Pollan article and the research done by Chana Palmer, Elisabeth M Bik, Daniel B DiGiulio, David A Relman, and Patrick O Brown. The fact that antibiotics caused such depletion in bacteria in the gut is just more proof of how new technology and innovations, although helpful in the short term, can cause long-term harm to our bodies. Also, having further researched the effects of cesarean section, one interview of Dr. Sakala, a doctor who studied comparisons between cesarean and vaginal childbirth, does not mention the risk of a lower bacterial count showing how this information is not very known to the public and possibly doctors. Based on this study, it is evident that our environment greatly impacts the development of our gut microbiota. Gut microbiota serve in many bodily functions and are necessary for survival, especially diverse ecosystems. The extent of importance of gut microbiota should be emphasized more not only in the world of science, but all people.

Works Cited:

Healthy Mothers Healthy Babies Coalition. What You Need to Know About Cesarean                 Section: An Interview with Dr. Carol Sakala of Childbirth Connection. Retrieved from           http://www.hmhb.org/virtual-library/interviews-withexperts/cesarean-section-c-                 section/

Palmer, C., Bik, E., DiGiulio, D., Relman, A., Brown, P., (2007). Development Of The                     Human Infant Intestinal Microbiota. DOI: 10.1371/journal.pbio.0050177.                          http://www.plosbiology.org/article/info%3Adoi%2F10.1371%2Fjournal.bio.0050177#abstract0

Pollan, M. (2013, May 15).  Some Of My Best Friends Are Germs. New                                       York Times, https://ctools.umich.edu/access/content/group/dd756836-7171-480e             b38d-66e2fc80511c/Readings/Pollan2013NYTimes.pdf

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