Sunday, July 17, 2011

Human Gut Microbiota Linked to Obesity

Obesity has recently become a hot topic in the United States as the number of cases of it rise in both adults and children. Because it can lead to many serious problems such as heart disease, cancer, musculoskeletal disorders and type 2 diabetes mellitus, and pulmonary hypertension, many scientists are searching for potential causes and preventive measures to combat it (Dibaise, 460). Recently, a connection has been discovered between obesity and certain forms of bacteria found in the human gut.

According to the article "Gut Microbiota and Its Possible Relationship with Obesity," gut microbiota is formed during the first year of development, and can be very different from person to person (462). However, the type of gut microbiota that is formed seems to have little to do with the lifestyle and age of the host, but is based mostly on its genetic information. This microbiota plays an important role in immune functions, food digestion and gastrointestinal tasks.

Some believe that gut microbiota have a specific metabolic rate and some of its traits may cause susceptibility to obesity. Though there are trillions of microbes living in the human gut, according to "Human Gut Microbes Associated with Obesity," two seem to be highly influential to adiposity- Bacteroidetes and Firmicutes. People who are obese have less Bacteroidetes than lean people and more Firmicutes.

To support this hypothesis, a study was done of 12 obese people who were put on a carbohydrate or fat restricted eating plan. Stools samples were collected over the course of one year and tested to determine the characteristic changes of their gut microbiota. The study found that, "Before diet therapy, obese people had fewer Bacteroidetes (P<0.001) and more Firmicutes (P=0.002) than did lean controls. Over time, the relative abundance of Bacteroidetes increased (P<0.001) and the abundance of Firmicutes decreased (P=0.002), irrespective of diet type" (Ley, 1023). Furthermore, increases in the amount of Bacteroidetes corresponded with the percentage of weight loss. As said by the conductors of the experiment, "Obesity is, to our knowledge, the only condition in which a pronounced, division-wide change in microbial ecology is associated with host pathology" (Ley, 1023).

This study supports their hypothesis that gut microbiota is connected to obesity and will hopefully aid in the development of preventive measures to fight obesity. As said in "Gut Microbiota and Its Possible Relationship with Obesity," "Although clearly no substitute for proper diet and exercise, manipulation of the gut microbiota may represent a novel approach for treating obesity, one that has few adverse affects" (466).


Dibaise, J.K., Husen, Z., Crowell, M.D., Krajmalnik-Brown, R., Decker, A.G., & Rittman, B.E. (2008). Gut Microbiota and Its Possible Relationship with Obesity. Mayo Clinic Proceedings, 83(4), 460-469Italic. Retrieved from Ebscohost.

Ley, R.E., Turnbaugh, P.J., Klein, S., & Gordon, J.I. (2006). Microbial Ecology: Human Gut Microbes Associated with Obesity. Nature, 444(7122), 1022-1023. doi: 10. 1038/4441022a. Retrieved from Ebscohost.
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