[ed. The microbiome -- exciting new frontier in medical diagnosis and treatment.]
The trillions of bacteria that live in the gut — helping digest foods, making some vitamins, making amino acids — may help determine if a person is fat or thin.
Dr. Jeffrey I. Gordon, left, and Vanessa K. Ridaura are two members of a scientific team whose research shows a connection between human gut bacteria and obesity.
The evidence is from a novel experiment involving mice and humans that is part of a growing fascination with gut bacteria and their role in health and diseases like irritable bowel syndrome and Crohn’s disease. In this case, the focus was on obesity. Researchers found pairs of human twins in which one was obese and the other lean. They transferred gut bacteria from these twins into mice and watched what happened. The mice with bacteria from fat twins grew fat; those that got bacteria from lean twins stayed lean.
The study, published online Thursday by the journal Science, is “pretty striking,” said Dr.Jeffrey S. Flier, an obesity researcher and the dean of the Harvard Medical School, who was not involved with the study. “It’s a very powerful set of experiments.”
Michael Fischbach of the University of California, San Francisco, who also was not involved with the study, called it “the clearest evidence to date that gut bacteria can help cause obesity.”
“I’m very excited about this,” he added, saying the next step will be to try using gut bacteria to treat obesity by transplanting feces from thin people.
“I have little doubt that that will be the next thing that happens,” Dr. Fischbach said.
But Dr. Flier said it was far too soon for that.
“This is not a study that says humans will have a different body weight” if they get a fecal transplant, he said. “This is a scientific advance,” he added, but many questions remain.
Dr. Jeffrey I. Gordon of Washington University in St. Louis, the senior investigator for the study, also urged caution. He wants to figure out which bacteria are responsible for the effect so that, eventually, people can be given pure mixtures of bacteria instead of feces. Or, even better, learn what the bacteria produce that induces thinness and give that as a treatment.
While gut bacteria are a new hot topic in medicine, he added that human biology is complex and that obesity in particular has many contributors, including genetics and diet.
In fact, the part of the study that most surprised other experts was an experiment indicating that, with the right diet, it might be possible to change the bacteria in a fat person’s gut so that they promote leanness rather than obesity. The investigators discovered that given a chance, and in the presence of a low-fat diet, bacteria from a lean twin will take over the gut of a mouse that already had bacteria from a fat twin. The fat mouse then loses weight. But the opposite does not happen. No matter what the diet, bacteria from a fat mouse do not take over in a mouse that is thin.
The trillions of bacteria that live in the gut — helping digest foods, making some vitamins, making amino acids — may help determine if a person is fat or thin.
Dr. Jeffrey I. Gordon, left, and Vanessa K. Ridaura are two members of a scientific team whose research shows a connection between human gut bacteria and obesity.The evidence is from a novel experiment involving mice and humans that is part of a growing fascination with gut bacteria and their role in health and diseases like irritable bowel syndrome and Crohn’s disease. In this case, the focus was on obesity. Researchers found pairs of human twins in which one was obese and the other lean. They transferred gut bacteria from these twins into mice and watched what happened. The mice with bacteria from fat twins grew fat; those that got bacteria from lean twins stayed lean.
The study, published online Thursday by the journal Science, is “pretty striking,” said Dr.Jeffrey S. Flier, an obesity researcher and the dean of the Harvard Medical School, who was not involved with the study. “It’s a very powerful set of experiments.”
Michael Fischbach of the University of California, San Francisco, who also was not involved with the study, called it “the clearest evidence to date that gut bacteria can help cause obesity.”
“I’m very excited about this,” he added, saying the next step will be to try using gut bacteria to treat obesity by transplanting feces from thin people.
“I have little doubt that that will be the next thing that happens,” Dr. Fischbach said.
But Dr. Flier said it was far too soon for that.
“This is not a study that says humans will have a different body weight” if they get a fecal transplant, he said. “This is a scientific advance,” he added, but many questions remain.
Dr. Jeffrey I. Gordon of Washington University in St. Louis, the senior investigator for the study, also urged caution. He wants to figure out which bacteria are responsible for the effect so that, eventually, people can be given pure mixtures of bacteria instead of feces. Or, even better, learn what the bacteria produce that induces thinness and give that as a treatment.
While gut bacteria are a new hot topic in medicine, he added that human biology is complex and that obesity in particular has many contributors, including genetics and diet.
In fact, the part of the study that most surprised other experts was an experiment indicating that, with the right diet, it might be possible to change the bacteria in a fat person’s gut so that they promote leanness rather than obesity. The investigators discovered that given a chance, and in the presence of a low-fat diet, bacteria from a lean twin will take over the gut of a mouse that already had bacteria from a fat twin. The fat mouse then loses weight. But the opposite does not happen. No matter what the diet, bacteria from a fat mouse do not take over in a mouse that is thin.
by Gina Kolata, NY Times | Read more:
Image: Dan Gill
