Altering gut biota has a direct effect on weight (new mouse study)
Today brings more fodder for the gut biota/obesity connection:
[URL="http://www.the-scientist.com/?articles.view/articleNo/34866/title/Microbes-Affect-Weight-Loss/"][B]Microbes Affect Weight Loss:[/B]
[I]Microbial changes in the gut contribute to a patient’s ability to slim down after gastric bypass surgery.[/I][/URL]
[QUOTE]Surgically bypassing the stomach is not the only reason that patients undergoing such a procedure quickly begin to drop pounds. Changes to the microbial make-up of their intestines also play a big role, according to a [URL="http://stm.sciencemag.org/content/5/178/178ra41"]paper published in Science Translational Medicine today[/URL] (March 27). The results suggest that tweaking a person’s gut microbes to mimic the effects of bypass treatment might, one day, be an effective means of losing weight without the need for surgery.
“What they’ve shown in this paper is that gastric bypass has an effect on the bacteria of the intestine, and that if you take those bacteria and transplant them into another mouse [that hasn’t had surgery] . . . that mouse [also] loses weight, which is amazing,” said Louis Aronne, a professor of medicine at Weill Cornell Medical College in New York, who was not involved in the study.[/QUOTE]
I don't have [URL="http://stm.sciencemag.org/content/5/178/178ra41.full"]fulltext access[/URL] for this journal unfortunately, but here's the abstract. [QUOTE][B]Conserved Shifts in the Gut Microbiota Due to Gastric Bypass Reduce Host Weight and Adiposity[/B]
[I]Alice P. Liou[SUP]1[/SUP], Melissa Paziuk[SUP]1[/SUP], Jesus-Mario Luevano Jr.[SUP]2[/SUP], Sriram Machineni[SUP]1[/SUP], Peter J. Turnbaugh[SUP]2[/SUP],* and Lee M. Kaplan[SUP]1[/SUP][/I]
[SUP]1[/SUP]Obesity, Metabolism & Nutrition Institute and Gastrointestinal Unit, Massachusetts General Hospital, Boston, MA 02114, USA.
[SUP]2[/SUP]FAS Center for Systems Biology, Harvard University, Cambridge, MA 02138, USA.
Roux-en-Y gastric bypass (RYGB) results in rapid weight loss, reduced adiposity, and improved glucose metabolism. These effects are not simply attributable to decreased caloric intake or absorption, but the mechanisms linking rearrangement of the gastrointestinal tract to these metabolic outcomes are largely unknown. Studies in humans and rats have shown that RYGB restructures the gut microbiota, prompting the hypothesis that some of the effects of RYGB are caused by altered host-microbial interactions.
To test this hypothesis, we used a mouse model of RYGB that recapitulates many of the metabolic outcomes in humans. 16[I]S[/I] ribosomal RNA gene sequencing of murine fecal samples collected after RYGB surgery, sham surgery, or sham surgery coupled to caloric restriction revealed that alterations to the gut microbiota after RYGB are conserved among humans, rats, and mice, resulting in a rapid and sustained increase in the relative abundance of Gammaproteobacteria ([I]Escherichia[/I]) and Verrucomicrobia ([I]Akkermansia[/I]). These changes were independent of weight change and caloric restriction, were detectable throughout the length of the gastrointestinal tract, and were most evident in the distal gut, downstream of the surgical manipulation site.
[B]Transfer of the gut microbiota from RYGB-treated mice to non-operated, germ-free mice resulted in weight loss and decreased fat mass in the recipient animals relative to recipients of microbiota induced by sham surgery, potentially due to altered microbial production of short-chain fatty acids.[/B] These findings provide the first empirical support for the claim that changes in the gut microbiota contribute to reduced host weight and adiposity after RYGB surgery.[/QUOTE]Ian Spreadbury has [URL="http://www.marksdailyapple.com/forum/thread61457.html"]offered a hypothesis[/URL] as to how microbes promote obesity, inflammation and metabolic disease when coupled with a neolithic diet; it will be interesting to see how these ideas link up.