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Lack of Intestinal Bacteria Linked to Obesity

Mice fed a mucus-loving microbe lost weight.


The Burrill Report

“There is so much evidence in the literature that links this bacterium to human conditions”

Researchers have demonstrated a connection between obesity and a lack of mucus-loving intestinal bacteria, and showed that increasing the population of the bacteria in the gut can reduce obesity.

Using two mouse models to mimic obesity, researchers at the Catholic University of Louvain in Belgium determined that the bacterium A. muciniphila, responsible for digesting the glycoproteins in mucus known as mucins, which are secreted by intestinal epithelial cells, is significantly lower in obese and overweight children and in patients with inflammatory bowel disease.

“There is so much evidence in the literature that links this bacterium to human conditions,” says Patrice Cani, head of the research team that performed the studies.

While the connection between the bacteria that naturally live throughout our digestive system and the health status of our metabolic and immune systems has been recognized for several years, it was only recently that the link between a specific bacterium and obesity was identified.

The A. muciniphila gets its name from its ability to digest mucus secreted by intestinal epithelial cells. It makes up 3 percent to 5 percent of the microbes in a healthy mammalian gut, making it one of the major strains in our gastrointestinal tract. In the intestines of obese people and mice, and people with type 2 diabetes, however, levels of the bacterium are much lower. Until now, it was not clear how this bacterium might contribute to or cause obesity, and how it might be leveraged to reduce the disease.

Compared to mice fed normal diets, the genetically modified mice had 3,300 times less A. muciniphila in their guts and mice fed a high-fat diet had 100 times less. The researchers restored normal levels of the bacterium in the feeding mice by including live A. muciniphila in their food or by including a simple sugar that encourages the growth of this specific bacterial strain in their drinking water.

Those mice lost weight, had a better ratio of fat to body mass, a reduced insulin resistance, and a thicker layer of intestinal mucus when they were fed the live bacteria. They also showed improvements in other markers related to obesity and metabolic disorders.

In addition, restoring normal levels of A. muciniphila increased intestinal levels of endocannabinoids, molecules that help regulate both blood-glucose levels and the gut's immune defenses against harmful microbes.

Altering the gut’s microbe population may one day be a mechanism to treat disorders such as obesity, diabetes, and colitis, he believes.

May 15, 2013

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