Archive for March, 2013

Can Microbes Help Us Loose Weight?

Sunday, March 31st, 2013

Gut Microbes may be key players in the weight battle, according to new studies. In people, microbial cells outnumber the human ones in several orders of magnitude, and recent studies reflect a growing awareness of the crucial role played by trillions of bacteria and other microorganisms that live in a specific ecosystem in the gut. Perturbations in this environment can have profound and sometimes devastating effects for the host. Microbiome, which is the totality of microbes, their genetic elements (genomes), and environmental interactions in a defined environment, have been a subject of research since they may be able to explain some complex diseases opening new opportunities for drug development and therapies. Studies mainly funded by the National Institutes of Health (NIH) in the United States for the Human Microbiome Project (HMP) demonstrate important correlations between the microbiome and human health and disease. These projects will leverage advances made by the HMP’s large scale sequencing efforts, with the advancement of new tools and technology to examine the relationship between changes in the human microbiome and diseases of interest. Fifteen Projects studying the relationship of microbiomes with cancer, autoimmune diseases and other factors are ongoing (for more information see NIH Human Microbiome Project’s Webpage). In one of such studies, the results obtained suggest that the specific effects of gastric bypass surgery (generally used to decrease the size of the stomach in obese people, so they can loose weight) on the microbiota contribute to its ability to cause weight loss and that finding ways to manipulate microbial populations to mimic those effects could become a valuable new tool to address obesity (see more in the article “Gut Microbes could help us loose weight” by Emily Singer at the MIT Technology Review). Previous studies with people and mice have found that the nature of microbes in the intestines changes after gastric bypass, with some groups growing more prominent and others decreasing in number. However, nobody was able to demonstrate whether the altered microbial composition was merely a side effect of the bypass surgery, or whether shifting bacterial populations could help people lose weight. In order to address this question, Kaplan and colleagues used a diet rich in fat to feed mice and then performed either bypass or a “placebo” surgery on the animals. Mice in the bypass group lost around 30 percent of their body weight within three weeks of the procedure. But even before the mice dropped weight, those in the bypass group already had an altered mix of intestinal bacteria. In addition, the bypass mice had more of certain types of microbes called Gamma proteobacteria, particularly Escherichia species compared to the other group. Some species of Escherichia are pathogenic, but others help prevent inflammation and maintain intestinal health. Mice that did a bypass surgery also had more Akkermansia bacteria, which can feed cells in the intestines with mucus, particularly when the host is cutting calories (for more information check the scientific article “Conserved Shifts in the Gut Microbiota Due to Gastric Bypass Reduce Host Weight and Adiposity” by Liou et al). The group speculates that the microbes somehow trigger fat-burning changes in the host’s metabolism. The researchers are now testing the effects of altering levels of individual microbes, as well as some of the chemicals they produce to see the effects. For example, gastric bypass changed the ratio of molecules called short-chain fatty acids, which often serve as chemical signals. Depending on the results, scientists might be able to create a cocktail of weight-loss microbes. So the answer is yes, our little friends (the microbes), could be of some help for people that need to loose weight. Maybe specific microbiota “pills” will be produced in the future, so you could just “rebuild” your gut microbial population to avoid getting fat and sick. Who knows? Let’s wait and see… (Image Source: Science Clarified)