Intestinal Bacteria May Explain Obesity

The Associated Press
Tuesday, June 13, 2006; 9:25 PM

ST. LOUIS -- The microorganisms that live in your gut could explain one of the sources of obesity, says a new study from researchers at Washington University.

Bacteria live throughout the body, but some intestinal bacteria appear to be better than others at helping their hosts turn food into energy, say researchers Buck S. Samuel and Dr. Jeffrey I. Gordon.

They believe changing the mix of bacteria in the intestine could influence how much people weigh.

Bacteria and archaea, another kind of single-celled organism, are common in the human intestine. Researchers are discovering that together, they help their human hosts extract calories and nutrients from food.

"We know very little about who they are and what they do," said Dr. Martin J. Blaser, chair of medicine at New York University.

Samuel decided to investigate that question by inoculating identical mice with different microbes, or a combination of two of the single-celled organisms.

The researchers found mice whose guts were inoculated with just the bacterium Beta thetaiotaomicron (B. theta) could process rodent food better than mice that were given no bacteria.

A second group of mice were inoculated with a combination of B. theta and an archaeon called Methanobrevibacter smithii (M. smithii). Those rodents could extract many more calories from the same amount of food, but they stored the extra energy as excess fat.

The researchers haven't yet concluded whether obese people have more M. smithii in their intestines. But Blaser said he believes scientists could eventually help control human nutrition by manipulating the types of microbes living in the gut.

The results of the study will be published online this week in the Proceedings of the National Academy of Sciences.

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Information from: St. Louis Post-Dispatch, http://www.stltoday.com

http://www.washingtonpost.com/wp-dy...6061301608.html

This whole area is is interesting to me. I just read an article that discusses how babies get their first bacteria and how antibiotics forever change the sort of bacteria we have. There's even a bacteria that they think is helpful to digesting oxalates and could prevent kidney stones! But this is a really new area of interest and there isn't a whole lot that is known.

This is interesting. It could account for part of the reason weight loss surgery (particularly gastric bypass) has a higher success rate than dieting. In a gastric bypass a small portion of the intestinal tract (generally less than 10%) is lost in reattaching the new small stomach pouch to the intestinal tract.

In addition, I come from a family where obesity runs pretty rampant. My sister however, was born a little prematurely with her intestinal tract not fully developped. She has never had any weight issues. It's possible that she has a different bacterial mix than the rest of the family because of that, explaining her lack of issue with obesity.

I find it fascinating that everything we "know" isn't necessarily fact. New ideas and concepts are constantly being introduced into our world. I can forsee a day somewhere, a very long time off, no doubt, where they will see us treating obesity with diet and exercise in the same way that we now look at treating cancer with leeches. And people will find it amazing that we didn't know that obesity was really caused by "x-whatever".

Val

I think a large reason LC helps is because sugar feeds parasites - good and bad. On a LC diet, I display almost zero symptoms of fungus/mold (like nasal drip, rashiness). I never get sick anymore. You know what? I bet the bugs in my gut also aren't quite as plentiful. A blood sugar level that is constantly low = good mojo .

One thing that has me confused, is that people intentionally eat cultured yogurts because it is supposed to augment weight loss. If we reason that bugs are energy factories, why would eating fermented yogurt help us lose weight? The only thing I can reason is that the bugs are eating the yogurt, and perhaps some food in our bodies, but they don't colonize our intestines...


PS nancy, could you link up those articles about intestinal bacteria? I find this very facinating and personally I do think it is a big part of why some people seem to be more weight loss resistant...

I also here that the "good bacteria" crowd out the bad bacteria, that's why you want to eat more bacteria.

Here's a link about gut bacteria: http://brain.hastypastry.net/forums...ad.php?t=134476

Bunch of links in that thread.

http://aem.asm.org/cgi/content/abstract/68/8/3841

I doubt that the human intestional bateria have changed from 50 years ago, although obesity rates have.

While this theory is interesting, I don't buy into it at this point.

No, but the use of antibiotics have increased hugely in the last 50 years.

Excellent point, Nancy.

Two generations for humans, but 50 years is a LOT of generations for bacteria.

I have become interested in Methanobrevibacter smithii since reading some of the stories in the popular press.

Based on this article summary:
http://www.ncbi.nlm.nih.gov/entrez/...6&dopt=Abstract

It appears that only Flagyl could reduce (and maybe eliminate) it, while other antibiotics would seem to eliminate only its competition.

Perhaps that's why cattle gain more weight when fed antibiotics such as monensin, flavophospholipol, avilamycin and salinomycin. The antibiotics allow m. smithii to become the dominant player (or one of the dominant players) in the gut. That would be bad news, because while on the one hand m. smithii extracts more calories from food, m. smithii also seems to be able to open cellular gates that allow fat into the cells that store it:
http://www.medicalnewstoday.com/med...hp?newsid=15752

I wonder if any doctors have started prescribing Flagyl off-label to control obesity? Maybe there are some studies going on...

Can you provide more information on the paper that said this? Thanks.

Flagyl was commonly prescribed for lots of things 20-30 years ago, but I don't know anyone who has been prescribed it recently. The newer, fancier ones seem to be what the doctors push these days (probably because of all the promotional literature). Coincidence?

Since I'm allergic to many antibiotics, I avoid them if I can, but as far as I know I am not allergic to Flagyl. Perhaps I'll ask about it if I ever need antibiotics again.

http://www.emedicine.com/med/topic3027.htm

A poster with the handle "Niels Godfredsen" in the Nature Newsblog seems to believe that Flagyl may have contributed to his inability to keep his weight up: