Thin People Poop May Become Obesity Cure

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In a new article published in the current issue of Science, researchers have discovered that one potential way to cure obesity in some people may be through the use of poop from thin people―more specifically, replacing bad obesity-causing bacteria in the guts of obese people with good fat-inhibiting bacteria from people who are thin.

The basis of this discovery comes from the relatively recent success scientists have found with treating irritable bowel syndrome and other digestive disorders with a treatment called “fecal swapping.”

Fecal swapping is the transplantation of fecal waste from the digestive tract of a healthy person into the digestive tract of an unhealthy person. Presumably how this works is that fecal swapping places good bacteria into an unhealthy digestive tract that is filled with bad disease-causing bacteria. The good bacteria will then inhabit and remain in the digestive tract and negate the negative health effects caused by the bad bacteria. Other successes with fecal swapping include reducing insulin resistance that is often associated with obesity.

In the Science published study, researchers have taken a related approach toward the role intestinal bacteria plays in health by asking how intestinal bacteria differ between lean people and obese people. To test this, the researchers turned to a special mouse animal model that possesses no bacteria in their gut. Using gut bacteria extracted from sets of twins where one twin is lean and other obese, Vanessa Ridaura, a graduate student at Washington University's School of Medicine, and her colleagues, transferred gut bacteria from lean and obese humans into the intestinal tracts of lean non-bacteria containing mice.

What resulted was that mice given intestinal bacteria from obese individuals gained 10% more fat than the mice that were provided with bacteria from the lean individuals. According to a news release from Science, this led the researchers to posit that the transplantation of gut microbes from humans to mice led to metabolic changes in the mice that are associated with human obesity.

"The first thing that Vanessa identified in these mice, which were consuming a standard mouse diet, was that the recipients of the obese twins' microbiota gained more fat than the recipients of the lean twins' microbiota," explained Jeffrey Gordon, director for the Center of Genome Sciences and Systems Biology at Washington University School of Medicine and a co-author of the Science report. "This wasn't attributable to differences in the amount of food they consumed, so there was something in the microbiota that was able to transmit this trait.”

To test their results further, the researchers then housed mice with bacteria from lean people with mice carrying bacteria from obese people. The test was to see if leanness could be transferred to the obese mice. This transfer was mediated by the fact that mice tend to eat one another’s bacteria-containing waste when caged together.

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After just 10 days the researchers found that the obese bacteria mice adopted the leaner physical and metabolic features of their lean bacteria cage mates, whereas the lean bacteria mice did not appear to be affected with any signs of obesity. The researchers identified specific bacteria called “Bacteroidetes” that are found in the lean mice that appear to be responsible for conferring leanness to the mice that originally received obese human bacteria.

Taking their results one step further, the researchers decided to see whether the diet of the mice made any difference in their results. They tested this by feeding groups of both the lean bacteria mice and the obese bacteria mice either a diet high in fiber and low in saturated fats or low in fiber and high in saturated fats.

What they found was that diet does make a difference. When both types of mice were housed together and fed a healthy high-fiber/low-fat diet, the results were the same—leanness i.e. the bacteroidetes bacteria were transferred from lean mice to obese mice. But, when both types of mice were housed together and fed a low-fiber/ high-fat diet, there was no transfer of leanness and the bacteroidetes bacteria.

The combined results indicated to the researchers that there is a complex interplay between gut bacteria, metabolism and diet that opens the possibility of finding a way to treat obesity in humans.

"We now have a way of identifying such interactions, dependent on diet, and thinking about what features of our unhealthy diets we could transform in ways that would encourage bacteria to establish themselves in our guts, and do the jobs needed to improve our well-being," said Gordon. "In the future, the nutritional value and the effects of food will involve significant consideration of our microbiota—and developing healthy, nutritious foods will be done from the inside-out, not just the outside-in."

For an informative article about fecal transfer, click-on the titled link “Fighting Bacterial Infection with Bacteria: Fecal Transplant.”

Image Source: Courtesy of PhotoBucket

Reference: "Gut Microbiota from Twins Discordant for Obesity Modulate Metabolism in Mice," Science 6 September 2013: Vol. 341 no. 6150; V.K. Ridaura et al Science, 2013

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