Twin Study Reveals How Gut Microbes Can Help Combat Obesity

Chuck Bednar for redOrbit.com – Your Universe Online
By studying pairs of twins, scientists from King’s College London and Cornell University have discovered that genetic factors influence whether people are fat or thin based on the type of microbes that thrive in their bodies.
The research, published in Thursday’s edition of the journal Cell, identified a specific family of bacteria that is highly heritable and more common in men and women with low body weight. Furthermore, it was found to help prevent weight gain when transplanted into mice.
Senior author Ruth Ley, an assistant professor in the Cornell University Department of Microbiology, and her colleagues explained that their research could pave the way for personalized probiotic treatments specially designed to help reduce the risk of obesity-related conditions based on a person’s individual genetic make-up.
“Up until now, variation in the abundances of gut microbes has been explained by diet, the environment, lifestyle, and health,” Ley explained. “This is the first study to firmly establish that certain types of gut microbes are heritable – that their variation across a population is in part due to host genotype variation, not just environmental influences.”
Both genetic variation and the gut microbe composition had previously been linked to metabolic disease and obesity, but even so, experts had long assumed that the link between human genetic variation and the diversity of gut microbes was negligible. The new National Institutes of Health (NIH)-funded study found otherwise, though.
Ley and her colleagues sequenced the genes of microbes found in over 1,000 fecal samples from 416 pairs of twins. They found that the abundances of specific microbe types were typically more similar in identical twins than in non-identical twins. The discovery indicates that genes influence the composition of gut microbes, the authors said.
The type of bacteria found to be most heavily influenced by the genetic makeup of the host was a member of a recently identified family known as Christensenellaceae, the researchers reported. Members of this health-promoting bacterial family were found to be more abundant in people with lower body weight than in obese individuals.

Image Above: Microbes in the family Christensenellaceae were found to be the most heritable gut bacteria in a study of twins. Credit: Jillian L. Waters/Ley lab
Furthermore, since otherwise healthy mice that had been treated with Christensenella minuta gained less weight than untreated rodents, increasing its prevalence in a person’s gut could help prevent or reduce obesity, the study authors noted. Experts from Bar Ilan University and University of Minnesota were also involved in the research.
“Our findings show that specific groups of microbes living in our gut could be protective against obesity – and that their abundance is influenced by our genes. The human microbiome represents an exciting new target for dietary changes and treatments aimed at combating obesity,” Professor Tim Spector, head of the King’s College London Department of Twin Research and Genetic Epidemiology, said in a statement.
“Our results showing that bacterial abundances run in families may be useful for disease risk prediction,” added Ley. “The microbiome is also an attractive target for therapeutic manipulation. By understanding the nature of our association with these health-associated bacteria, we could eventually exploit them to promote health.”
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