Why (and how) our gut bacteria is important to us

Judy Keen
Sep 10, 2013

Our gut contains millions of bacteria. These symbiotic organisms, called the microbiome, help with digestion of food. As recent studies show, the microbiome can significantly impact the development of obesity by influencing fat accumulation.

Two recently published studies in the journals Science and Nature demonstrated that the type and amount of bacteria in the intestine can affect obesity or leanness. These studies suggest that the diversity of types (and number) of bacteria is an important factor related to body fat. Low diversity of bacteria species are seen in individuals with higher levels of inflammation and inflammatory bowel disease. Conversely, lean individuals have larger diversity and a different population of bacteria.

The research also suggests that changing the bacterial population in your gut can alter your overall weight. Transferring bacteria from obese to lean mice resulted in the development of obesity, while the bacteria from lean individuals transferred to obese mice aided in the reversal of obesity. Further, the bacterial makeup of your gut can be altered by the food you ingest. Therefore, a key to changing your weight may reside in the bacteria in your gut, which is influenced by the types of food you eat.

So how does this bacteria influence weight? Early evidence indicates that the bacteria in our gut digest fats in food into short chain fatty acids (SCFAs) that are used for energy. In lean mice, more SCFAs are produced and absorbed into the body through the small intestine than in obese mice. New evidence is emerging showing that the obesity is not the result of lower SCFAs absorbed, but rather that these SFCAs prevent the accumulation of fat (adiposity) in the body. Therefore, leanness is a result of less fat accumulation resulting from higher levels of SCFAs.

As we learn more about the development and control of obesity and potential methods to regulate it, concerns arise. Will health insurance companies provide coverage for any therapies that result? How is discrimination against individuals avoided?

Photo by Rocky Mountain Laboratories, NIAID, NIH downloaded from the Wikipedia Commons Attribution 2.0 Generic license.

Judy Keen

Judy is a S&T Alumni Fellow (HEHS, 2012-2014). She blogs about the latest cancer research, increasing the access to the scientific literature, and graduate education. Follow Judy on twitter @judykeenphd or at


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Comments (1)

Kendra Zamzow (not verified)
September 27, 2013 at 2:43 pm
It would be interesting to see how, and in what ways and over what period of time, gut bacteria change when an individual gains or loses weight. It makes sense to me that eating different foods would influence the microflora, but makes less sense to me that transplanting gut flora would have a long term impact if the ingested foods didn't change.

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