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Quercki : microbes   11

Is eating behavior manipulated by the gastrointestinal microbiota? Evolutionary pressures and potential mechanisms

Microbes in the gastrointestinal tract are under selective pressure to manipulate host eating behavior to increase their fitness, sometimes at the expense of host fitness. Microbes may do this through two potential strategies: (i) generating cravings for foods that they specialize on or foods that suppress their competitors, or (ii) inducing dysphoria until we eat foods that enhance their fitness. We review several potential mechanisms for microbial control over eating behavior including microbial influence on reward and satiety pathways, production of toxins that alter mood, changes to receptors including taste receptors, and hijacking of the vagus nerve, the neural axis between the gut and the brain. We also review the evidence for alternative explanations for cravings and unhealthy eating behavior. Because microbiota are easily manipulatable by prebiotics, probiotics, antibiotics, fecal transplants, and dietary changes, altering our microbiota offers a tractable approach to otherwise intractable problems of obesity and unhealthy eating.
Keywords: cravings, evolutionary conflict, host manipulation, microbiome, microbiota, obesity
diet  health  mood  obesity  microbes  gut  brain 
8 weeks ago by Quercki
The neuroactive potential of the human gut microbiota in quality of life and depression | Nature Microbiology
The neuroactive potential of the human gut microbiota in quality of life and depression

Article | Published: 04 February 2019
The neuroactive potential of the human gut microbiota in quality of life and depression

Mireia Valles-Colomer, Gwen Falony, Youssef Darzi, Ettje F. Tigchelaar, Jun Wang, Raul Y. Tito, Carmen Schiweck, Alexander Kurilshikov, Marie Joossens, Cisca Wijmenga, Stephan Claes, Lukas Van Oudenhove, Alexandra Zhernakova, Sara Vieira-Silva & Jeroen Raes

Nature Microbiology (2019) | Download Citation

The relationship between gut microbial metabolism and mental health is one of the most intriguing and controversial topics in microbiome research. Bidirectional microbiota–gut–brain communication has mostly been explored in animal models, with human research lagging behind.
microbes  research  legit 
february 2019 by Quercki
Links between gut microbes and depression strengthened
Much of what we know so far is based on studies showing correlations between specific gut bacteria, their metabolites and neurological symptoms. But these correlations do not prove cause and effect. Many studies use animal models, which don’t accurately mirror human traits or behaviours. Human studies have been limited: they’re usually based on relatively small numbers of people, and might not control for a wealth of confounding factors — such as unusual diets, antibiotics or antidepressants — that can affect the microbiota.

Read the paper: The neuroactive potential of the human gut microbiota in quality of life and depression

A study published this week in Nature Microbiology tackles some of these issues (M. Valles-Colomer et al. Nature Microbiol.; 2019). The authors used DNA sequencing to analyse microbiota in the faeces of more than 1,000 people enrolled in Belgium’s Flemish Gut Flora Project. The team then correlated different microbial taxa with the participants’ quality of life and incidence of depression, using self-reported and physician-supplied diagnoses. The researchers validated the findings in an independent cohort of 1,063 individuals in the Netherlands’ LifeLines DEEP project. Finally, they mined the data to generate a catalogue describing the microbiota’s capacity to produce or degrade molecules that can interact with the human nervous system.
microbes  depression  research 
february 2019 by Quercki
‘For 30 years I’ve been obsessed by why children get leukaemia. Now we have an answer’ | Science | The Guardian
“It is a feature of developed societies but not of developing ones,” Greaves adds. “The disease tracks with affluence.”

Acute lymphoblastic leukaemia is caused by a sequence of biological events. The initial trigger is a genetic mutation that occurs in about one in 20 children.

“That mutation is caused by some kind of accident in the womb. It is not inherited, but leaves a child at risk of getting leukaemia in later life,” adds Greaves.

For full leukaemia to occur, another biological event must take place and this involves the immune system. “For an immune system to work properly, it needs to be confronted by an infection in the first year of life,” says Greaves. Without that confrontation with an infection, the system is left unprimed and will not work properly.”
germs  immune  leukemia  medicine  cancer  microbes 
january 2019 by Quercki
So Your Kitchen Sponge Is A Bacteria Hotbed. Here's What To Do : The Salt : NPR
Anyone who has worked with food-borne pathogens — or their close relatives — knows that these little critters aren't "the strongest." They are weaklings. You heat them up just a little bit and they literally pop!

"That's why we cook food. We know that heating will kill the pathogens," says Jennifer Quinlan, a food microbiologist at Drexel University.

So what in the heck is going on with this new sponge study? Are the findings upturning decades of public health recommendations?

Not at all, Quinlan says. The media reports were simply not accurate.

"After you contacted me for an interview, I read the study in great detail," she says. "I feel now that the comments they make about not recommending washing in the abstract are really, really misleading."

In fact, she says, you can't draw any conclusions about the effect of washing sponges from this study.

For starters, there was no clear explanation of what "regular cleaning" meant, she says.
sponge  bacteria  microbes  microwave  clean 
september 2017 by Quercki
Eating Yogurt Is Not Enough: Rebalancing The Ecosystem Of 'The Microbes Within Us' : NPR
Ed Yong, author of I Contain Multitudes, says someday we might be able to improve our health by taking probiotics, but "we are still in the very early stages of working out how to do this."
microbes  babies  breastmilk  mosquito 
august 2016 by Quercki
Joint Pain, From the Gut - The Atlantic
Several recent studies have found intriguing links between gut microbes, rheumatoid arthritis, and other diseases in which the body’s immune system goes awry and attacks its own tissue.  

A study published in 2013 by Jose Scher, a rheumatologist at New York University, found that people with rheumatoid arthritis were much more likely to have a bug called Prevotella copri in their intestines than people that did not have the disease. In another study published in October, Scher found that patients with psoriatic arthritis, another kind of autoimmune joint disease, had significantly lower levels of other types of intestinal bacteria.

"This is frontier stuff. With the microbiome, we’ve added a new player to the game."
This work is part of a growing effort by researchers around the world to understand how the microbiome—the mass of microbes that live in the gastrointestinal tract—affects our overall health. The gut contains up to a thousand different bacteria species, which together weigh between one and three pounds. This mass contains trillions of cells, more than the number of cells that make up our own bodies. Over the past several years, scientists have compiled a growing collection of evidence that many of these bugs may have a major effect on our well-being, with some triggering chronic, non-infectious ailments such as rheumatoid arthritis, and others protecting against such diseases.
microbes  gut  arthritis 
april 2015 by Quercki
BBC News - Woman's stool transplant leads to 'tremendous weight gain'
The 32-year old woman, who has not been indentified, had an infection that could not be treated with even the most powerful antibiotics.

Dr Colleen Kelly, from the Medical School at Brown University, said the option of a faecal transplant was discussed and the woman wanted to use a relative - her daughter.

The daughter was overweight at the time and was on her way to becoming obese.

The procedure did clear the woman's infection.

But Dr Kelly told the BBC News website: "She came back about a year later and complained of tremendous weight gain.

"She felt like a switch flipped in her body - to this day she continues to have problems."

She started with a Body Mass Index of 26. Sixteen months after the procedure she had a BMI of 33 and three years after it, a BMI of 34.5.
fat  microbes  transplant 
february 2015 by Quercki
A gut infection can keep mice lean | Nutrition | Science News
Skinniness could be contagious. Gut bacteria from thin people can invade the intestines of mice carrying microbes from obese people. And these invaders can keep mice from getting tubby, researchers report in the Sept. 6 Science.

“It’s very surprising,” says molecular microbiologist Andreas Schwiertz of the University of Giessen in Germany, who was not involved in the work. “It’s like a beneficial infection.”

But the benefits come with a catch. The invading microbes drop in and get to work only when mice eat healthy food. Even fat-blocking bacteria can’t fight a bad diet, suggests study leader Jeffrey Gordon, a microbiologist at Washington University in St. Louis.

In recent years, researchers have collected clues that suggest that gut microbes can tweak people’s metabolism. Fat and thin people have different microbes teeming in their intestines, for example. And normal-weight mice given microbes from obese mice pack on extra fat, says coauthor Vanessa Ridaura, also of Washington University.

These and other hints have led researchers to experiment with fecal transplants to flush out bad gut microbes and dump in good ones. The transplants can clear up diarrhea and may even help some obese people regain insulin sensitivity. But feces can house dangerous microbes as well as friendly ones.
diet  obesity  microbes  research 
september 2013 by Quercki
You Are Your Bacteria | MIT Technology Review
After a trip to Peru last year, microbiologist Rob Knight came home with a horrendous case of traveler’s diarrhea. He took some antibiotics and quickly recovered. But because Knight had been participating in one of his own studies of the human microbiome–the diverse collection of bacteria and other organisms that inhabit our gut, skin, mouths, and other parts–he could examine how the drugs changed the microbial population in his gut. Microbes did repopulate his digestive tract, but the community makeup was different.

Soon after his trip, Knight restarted a diet and exercise program that had previously proved ineffective at helping him lose weight. This time around, he lost 60 pounds. His mind went straight to his microbes. Previous research from his lab at the University of Colorado, in Boulder, showed that microbes can have a transmissible effect on weight–transplanting microbes from fat, hungry mice into normal mice causes the recipients to eat more and gain weight. “The conjecture was that the antibiotics might clear out the microbes that were already there and make it easier to reshape the community,” says Knight.

Of course, not everyone who takes antibiotics loses weight. And livestock are routinely given the drugs to beef up rather than slim down. But a growing body of evidence suggests that our microbes vary greatly from person to person and play a key role in both metabolism and obesity. By cataloging the variability in different individual’s microbial communities, as well as how those communities change in response to certain drugs or other environmental factors, scientists hope to harness the malleability of our microbes for medical uses.
diet  microbes  bacteria 
june 2013 by Quercki
AAAS - Winners Named in Science Journalism Awards -ALL
Spot News/Feature Reporting (20 minutes or less)
Sheraz Sadiq
KQED QUEST (San Francisco)
“Hetch Hetchy Aqueduct: Big Fixes for Big Quakes”
9 November 2011

Sheraz Sadiq
Much of the Hetch Hetchy water delivery system for the San Francisco Bay Area was built in the 1920s and 1930s with riveted steel pipes that don’t perform well during earthquakes. At a cost of $4.6 billion, the San Francisco Public Utilities Commission has been installing new pipes and employing state-of-the-art engineering elements. In a solid mix of historical footage and on-the-scene reporting, with an appreciation for the challenges involved, KQED’s Sheraz Sadiq explained the engineering steps being undertaken to protect the Bay Area’s water supply. Guy Gugliotta, a freelance science writer who helped judge the contest, called the KQED broadcast “a comprehensive look at the vulnerability of the water supply in the San Francisco Bay Area — something that should concern every resident.” He praised the “fascinating use of historical footage, outstanding engineering footage, and graphics” to tell the tale. “My editors and I knew from the outset that this would be a difficult story to tell,” Sadiq said. “It would need to cover the controversial history of Hetch Hetchy, explain how the current water system works and the complex, innovative work underway to keep the water flowing in the event of a major earthquake in the Bay Area.”
science  water  genetics  microbes  bacteria  SF 
november 2012 by Quercki

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