At risk. Changes in gut flora could help explain why obese mice are more likely to develop liver tumors (inset).
Credit: Eiji Hara/Japanese Foundation for Cancer Research
Posted on 06/27/2013 2:24:27 AM PDT by neverdem
Why does obesity raise the risk of developing cancer? A new study suggests that the wrong mix of gut bacteria could be to blame. Researchers report that obese mice carry altered communities of intestinal bugs, which produce DNA-damaging acid that leave the mice more susceptible to liver cancer. The findings hint that bacteria help drive cancer development and may eventually help scientists better predict and prevent the disease.
Obesity increases the odds of falling victim to certain types of cancer, including colorectal and liver tumors, but scientists haven't been able to identify the mechanism behind this link. They've suspected that our gut microbiota—the complex community of trillions of microbes living in our intestines—play a role. After all, gut bugs have been linked to other diseases, including inflammatory bowel disease, allergies, and even heart disease, and are known to differ between lean and obese individuals.
Molecular biologist Eiji Hara of the Cancer Institute at the Japanese Foundation for Cancer Research in Tokyo and colleagues set out to connect the dots between cancer and gut microbes by studying the development of cancer in obese and lean mice. They began with two groups of mice: lean mice that grew up on a normal diet and mice that ate a fat-laden diet until they were obese. To induce the rodents to develop cancer—"Mice don't smoke or drink alcohol, so they're fairly cancer-free," Hara says—they exposed the animals to a cancer-causing chemical shortly after birth.
The mice revealed the same obesity-cancer link observed in humans and other animals. Only 5% of the lean mice exposed to the carcinogen developed cancer later in life, whereas all the obese mice did. When the researchers reproduced the experiment using mice bred to be obese even on a normal diet, they also saw a greater incidence of cancer, which suggests that obesity itself—and not the animals' diet—increased their cancer risk.
The obese mice were prone to liver cancer, and their tumors showed high concentrations of molecules, called proinflammatory cytokines, that trigger inflammation. The obese mice also had higher levels of deoxycholic acid (DCA), a byproduct left over after certain gut microbes break down bile acids produced by the liver. DCA damages DNA and has been associated with some cancers in humans.
To trace the origins of these two signs—the presence of inflammation-promoting cytokines and the higher levels of DCA—the researchers scrutinized the animals' guts. They found that the obese mice hosted a different mix of bacteria. So-called Gram-positive bacterial strains, in particular, seemed to thrive in the plumper mice. When Hara and his colleagues treated the mice with vancomycin, an antibiotic that targets Gram-positive bacteria, the animals showed a reduction in their cancer incidence and their levels of DCA. Moreover, reducing the animals' DCA levels directly (by stimulating more bile acid secretion or slowing down bile acid breakdown) also reduced their cancer risk, and giving them extra DCA increased their risk, the team reports online today in Nature.
Together, the findings suggest that obesity triggers a cancer-causing domino effect in which DCA plays a key part, Hara says. The gut microbiota changes, boosting the populations of gut bugs that produce more DCA. Then the excess DCA causes DNA damage and inflammation in the liver, which, in turn, leads to liver cancer.
"I was very surprised by the process," Hara says. "We never expected that changes in the gut microbiota could cause the higher risk of cancer."
"I think this study is very exciting," says Peter Turnbaugh, a microbiologist from Harvard University who was not involved in the work. "It's been a mystery for quite some time why obesity leads to higher cancer risk. They make a compelling case that the microbial community is involved."
Turnbaugh notes that more research is needed to show that a similar mechanism is at work in humans. But if it is, the results could pave the way for better methods of predicting and preventing cancer. Tracking DCA levels, for example, could enable doctors to assess cancer risk and take steps toward prevention, he says.
"If it's true that production of this acid leads to cancer, there could be ways to inhibit the production by manipulating diet or fine-tuning people's microbial communities," Turnbaugh says. "But there's definitely a lot more to be learned first."
Wow! News to me!!! ;)
Yeah gut flora is important. This is why I do yeast cleanses and take an excellent probiotic. Really helps with many things. Something tells me the general obese person though is not caring for oneself in such away that they take probiotics and stay away from high glucose sugar long enough to do a yeast cleanse.
There’s a lot of research being done on gut flora that is leading to some very interesting data. Including some stuff done on insulin regulation and diabetes.
The more you eat, the harder the liver has to work. Smoking or drinking in concert with it only makes it that much worse. You’re talking about liver cancer, however, not liver failure. Although I am no food Nazi, there is a definite danger from obesity however you look at it. A co-worker of mine, who I sometimes said half-jokingly was a time-bomb, spent his last days in and out of consciousness while his liver failed.
Interesting, we drink homemade kefir with our raw goats milk and in the last couple of months also started brewing kombucha. Maybe we have all our microbe bases covered.
Kefir and kombucha are great places to begin. The real issue is the immune system. In a nutshell all those bad bugs in our gut and in our mouths are causing the immune system to work real hard on a daily basis to control those issues leaving little energy to attack things like cancer.
Gut Bugs? Nah...
How do you do a yeast cleaning?
Gut bugs?
I understand how to gut a fish, but how does one gut a bug?
does kombucha have microbes?
busy day but I will get back to you on this as well as the thread before sun down. got some great recommendations.
I believe they do, we are novices and have not researched it as much. We make a gallon a week using green tea and than after it’s brewed and done we add some dried blueberries to flavor it a bit. There is nutritional info on the website we got our starter scoby from www.kombuchakamp.com really good site. I am pretty sure the microbes are active even after refrigeration.
Either way the other very critical actions during the cleanse is to not eat phone that are either high in glucose (white breads etc as well as fruits that are high on the glycemic index. Also no brewer's yeast. There is a list of foods in the YeastMax directions I believe and also on line.
AFter the cleans I repopulated with good yeast with a product called Advanced Naturals Ultimate FloraMax Super Critical 200 billion live cultures per serving. THat lasted seven days I believe and then I take a daily from a brand called INNATE Flora 50 14 Clinical Strength..
These products worked for me. I have no relationship to them professionally. My nurse practitioner carries them. You can get them on-line too.
Definitely research on-line too. I have had wonderful results. If you have to take antibiotics (which kill all yeast and thus bad end up taking over when they come back because good are gone) or anything after the cleanse repopulate with the Super Critical before going back to daily probiotic.
No apparent link to humans?
Never met an obese person that had any kind of cancer, so this rings dissonant. Bad knees, bad feet, bad hips, sore backs, but cannot recall a single obese person with cancer.
More likely not.
This is not a medical story, its 100% big gov socialist control political.
Obesity is associated with increased risks of the following cancer types, and possibly others as well:
Esophagus, Pancreas, Colon and rectum, Breast (after menopause), Endometrium (lining of the uterus), Kidney, Thyroid, Gallbladder.
One study, using NCI Surveillance, Epidemiology, and End Results (SEER) data, estimated that in 2007 in the United States, about 34,000 new cases of cancer in men (4 percent) and 50,500 in women (7 percent) were due to obesity. The percentage of cases attributed to obesity varied widely for different cancer types but was as high as 40 percent for some cancers, particularly endometrial cancer and esophageal adenocarcinoma.
The reason you were likely unaware of this was because these are internal cancers that are likely in an advanced stage when they are first detected. On top of that, cancer and chemotherapy are a major weight loss program. I knew an obese woman whose cancer, though caught early, was terminal, and in six months she went from fat to “concentration camp”.
Her life was probably extended by three months by smoking marijuana, that permitted her to eat without nausea.
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