Bacterial Shift Seen in Junk-Food-Eating ‘Humanized’ Mice
For starters, the researchers fed their “humanized” mice various kinds of foods to see how the bacterial communities in their guts responded. The animals eating a “Western” high-fat, high-sugar diet packed on the ounces, but not before their microbiota shifted to a predominately “fat profile;” a transition that started within a few hours of their first junk-food meal.
In contrast, the mice eating a healthful low-fat, high plant polysaccharide diet remained lean. Moreover, when gut microbes collected from the mouse fatties were transferred to a second-generation of germ-free animals they too gained more weight than their counterparts who were eating exactly the same amount of healthful food but implanted with a more “normal” complement of intestinal bacteria.
“Thrifty” Bacteria Evolutionary Allies When Food was Scarce
From an evolutionary point of view this all makes sense: gut bacteria are food processors and in the ancient symbiosis between these microbes and their hosts, mice, humans, and virtually all other creatures, some evolved to provide more usable energy than others, becoming valuable allies when times were tough. But when food is abundant, these same bacteria become a problem, something which has become all too evident in the U.S. where food is plentiful and we spend upwards of $60 billion a year on obesity and obesity-associated disease such as type 2 diabetes and cardiovascular disease.
Establishing More “Normal” Populations of Gut Bacteria May Help with Weight Loss
“Large-scale alterations of the gut microbiota are associated with obesity and are responsive to weight loss,” concurs Ruth E Ley a microbiologist who once worked in Gordon’s lab and is now at Cornell University in Ithaca, New York. Importantly, restoring intestinal bacteria to a healthy state may reduce inflammation, insulin resistance, and limit the amount of energy turned into fat, Ley says.
Probiotics May Help But More Testing is Needed
Diet can do this and probiotic treatments aimed at establishing a more “normal” population of resident microbes in obese people might possibly help. In fact, our National Institutes of Health is so certain that probiotics will be commercially developed they are already exploring ways to examine their benefits and risks as well as regulate their use. The gnotobiotic mice, those with ‘humanized’ gut microbes developed by Gordon’s group, should prove valuable in these studies.
Professor Jeffrey I. Gordon, Director of the Center for Genome Sciences at the Washington University School of Medicine spoke at the New York Academy of Sciences onTuesday, May 18th and outlined his new research projects including a look at the gut virobiome. As would be expected, with all those bacteria about, the intestinal tract hosts a great variety of bacteriophages and other viruses.
Turnbaugh, P. J. et al. “A core gut microbiome in obese and lean twins.” Nature 2009 (457), pp.480-484.
Turnbaugh, P. J. et al. “The Effect of Diet on the Human Gut Microbiome: A Metagenomic Analysis in Humanized Gnotobiotic Mice.” Sci Trans Med (1) November 2009 (online).
Ley, R.E. “Obesity and the human microbiome.” Curr Opin Gastroenterol 2010 (26), pp. 5-11.
Quin, J. et al. “A human gut microbial gene catalogue established by metagenomic sequencing.” Nature 2010 (464), pp.59-65.
This article was originally published on Suite 101.
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