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Gut Microbes Linked To Brain Structure In People With Irritable Bowel Syndrome

 Summary:
Research shows for the first time an association between the gut microbiota and the brain regions involved in the processing of sensory information from their bodies. Also, the researchers gained insight into the connections among childhood trauma, brain development and gut microbiome composition.

A new study by researchers at UCLA has revealed two key findings for people with irritable bowel syndrome about the relationship between the microorganisms that live in the gut and the brain.

For people with IBS research shows for the first time that there is an association between the gut microbiota and the brain regions involved in the processing of sensory information from their bodies. The results suggest that signals generated by the brain can influence the composition of microbes residing in the intestine and that the chemicals in the gut can shape the human brain’s structure.

Additionally, the researchers gained insight into the connections among childhood trauma, brain development and the composition of the gut microbiome.

Previous studies performed in mice have demonstrated effects of gut microbiota on brain function and behavior, as well as the influence of the brain on the composition of microbes in the gut. However, to date, only one study performed in human subjects has confirmed the translatability of such findings to the human brain.

Studies have also reported evidence for alterations in the composition of gut microbiota in people with irritable bowel syndrome, but there has been little consistency among studies regarding the specific microbial alterations and the relationship of such alterations with the cardinal symptoms of IBS, recurring abdominal pain and altered bowel habits.

In relation to a person’s history with childhood trauma, it has been shown to be associated with structural and functional brain changes; trauma in young children has also been shown to alter gut microbial composition. But how they are related has been unknown.

The UCLA researchers collected behavioral and clinical measures, stool samples and structural brain images from 29 adults diagnosed with IBS, and 23 healthy control subjects. They used DNA sequencing and various mathematical approaches to quantify composition, abundance and diversity of the gut microbiota. They also estimated the microbial gene content and gene products of the stool samples. Then the researchers cross-referenced these gut microbial measures with structural features of the brain.

Based on the composition of the microbes in the gut, the samples from those diagnosed with IBS clustered into two subgroups. One group was indistinguishable from the healthy control subjects, while the other differed. Those in the group with an altered gut microbiota had more history of early life trauma and longer duration of IBS symptoms.

The two groups also displayed differences in brain structure.

Analysis of a person’s gut microbiota may become a routine screening test for people with IBS in clinical practice, and in the future, therapies such as certain diets and probiotics may become personalized based on an individual’s gut microbial profile. At the same time, subgroups of people with IBS distinguished by brain and microbial signatures may show different responsiveness to brain-directed therapies such as mindfulness-based stress reduction, cognitive behavioral therapy and targeted drugs.

A history of early life trauma has been shown to be associated with structural and functional brain changes and to alter gut microbial composition. It is possible that the signals the gut and its microbes get from the brain of an individual with a history of childhood trauma may lead to lifelong changes in the gut microbiome. These alterations in the gut microbiota may feed back into sensory brain regions, altering the sensitivity to gut stimuli, a hallmark of people with IBS.

 
Story Source:
Materials provided by University of California, Los Angeles (UCLA), Health Sciences. Note: Content may be edited for style and length.
 
Journal Reference:
Jennifer S. Labus, Emily B. Hollister, Jonathan Jacobs, Kyleigh Kirbach, Numan Oezguen, Arpana Gupta, Jonathan Acosta, Ruth Ann Luna, Kjersti Aagaard, James Versalovic, Tor Savidge, Elaine Hsiao, Kirsten Tillisch, Emeran A. Mayer. Differences in gut microbial composition correlate with regional brain volumes in irritable bowel syndrome. Microbiome, 2017; 5 (1) DOI: 10.1186/s40168-017-0260-z
 
University of California, Los Angeles (UCLA), Health Sciences.
“Gut microbes linked to brain structure in people with irritable bowel syndrome.” ScienceDaily. ScienceDaily, 5 May 2017.
 
source:  University of California, Los Angeles (UCLA), Health Sciences    www.sciencedaily.com/releases/2017/05/170505151656.htm
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Can Gut Bacteria Affect Alzheimer’s Disease?

New research finds the microbes in your gut may play a major role in escalating the chronic brain disease.

A raft of recent studies has shown that the microbiome is a factor in the development of obesity, type 2 diabetes, asthma, and cardiovascular disease. Now, we can add Alzheimer’s disease to the list.

A new study, published in Scientific Reports, has shown that certain gut microbiota may speed up the development of the chronic brain disease.

Researchers studied both healthy and diseased mice and found that those with Alzheimer’s had a different composition of gut bacterium. Healthy mice also had a lower level of beta-amyloid plaque in their brains than the mice with Alzheimer’s. (Beta-amyloid plaques are the lumps of protein fragments that form at nerve fibers, creating tangles leading to neuroinflammation.)

To further test the connection between intestinal flora and Alzheimer’s disease, researchers placed microbes from mice suffering from Alzheimer’s into germ-free mice. The result? The germ-free mice given the gut microbes from the mice with Alzheimer’s developed more beta-amyloid brain plaques than those who received bacteria from healthy mice.

“The results mean that we can now begin researching ways to prevent the disease and delay the onset,” researcher Frida Fåk Hållenius, PhD, of Sweden’s Lund University Food for Health Science Centre, says in a press release. “We consider this to be a major breakthrough as we used to only be able to give symptom-relieving antiretroviral drugs.”

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‘TAKE CARE OF YOUR MICROBIOME, IT’LL TAKE CARE OF YOU’
The findings open the door to testing new preventive and therapeutic strategies — such as dietary modification — on bacteria’s role in Alzheimer’s disease development.

In November 2016, for example, Iranian researchers found that probiotics helped improve memory in people suffering from severe Alzheimer’s disease. Although the sample size was small (60 participants) and the study lasted only 12 weeks, the results indicate that eating microbiome-boosting foods may improve memory in those who are cognitively impaired.

“If you take care of your microbiome, it’ll take care of you — and that’s all the way up to your brain,” says leading Alzheimer’s researcher Rudolph Tanzi, PhD.

To reduce your Alzheimer’s risk, Tanzi advises avoiding eating processed and other inflammation-promoting foods, which negatively affect gut microbial communities, and focusing on real food.

HEIDI WACHTER · FEB 16, 2017


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A Gut Makeover for the New Year

If you’re making resolutions for a healthier new year, consider a gut makeover. Refashioning the community of bacteria and other microbes living in your intestinal tract, collectively known as the gut microbiome, could be a good long-term investment in your health.

Trillions of microbial cells inhabit the human body, outnumbering human cells by 10 to one according to some estimates, and growing evidence suggests that the rich array of intestinal microbiota helps us process nutrients in the foods we eat, bolsters the immune system and does all sorts of odd jobs that promote sound health. A diminished microbial ecosystem, on the other hand, is believed to have consequences that extend far beyond the intestinal tract, affecting everything from allergies and inflammation, metabolic diseases like diabetes and obesity, even mental health conditions like depression and anxiety.

Much of the composition of the microbiome is established early in life, shaped by forces like your genetics and whether you were breast-fed or bottle-fed. Microbial diversity may be further undermined by the typical high-calorie American diet, rich in sugar, meats and processed foods. But a new study in mice and people adds to evidence that suggests you can take steps to enrich your gut microbiota. Changing your diet to one containing a variety of plant-based foods, the new research suggests, may be crucial to achieving a healthier microbiome.

Altering your microbiome, however, may not be easy, and nobody knows how long it might take. That’s because the ecosystem already established in your gut determines how it absorbs and processes nutrients. So if the microbial community in your gut has been shaped by a daily diet of cheeseburgers and pepperoni pizza, for example, it won’t respond as quickly to a healthy diet as a gut shaped by vegetables and fruits that has more varied microbiota to begin with.

“The nutritional value of food is influenced in part by the microbial community that encounters that food,” said Dr. Jeffrey Gordon, the senior author of the new paper and director of the Center for Genome Science and Systems Biology at the Washington University School of Medicine in St. Louis. Nutritional components of a healthy diet have to be viewed from “the inside out,” he said, “not just the outside in.”

One of the questions the study set out to answer was how individuals with different diets respond when they try to improve their eating habits. The scientists harvested gut bacteria from humans, transplanted them into mice bred under sterile conditions, and then fed the mice either American-style or plant-based diets. The scientists then analyzed changes in the mice’s microbial communities.

Of interest, the scientists harvested the gut bacteria from people who followed sharply different diets. One group ate a fairly typical American diet, consuming about 3,000 calories a day, high in animal proteins with few fruits and vegetables. Some of their favorite foods were processed cheese, pepperoni and lunch meats.

love-your-gut

The other group consisted of people who were devotees of calorie restriction. They ate less than 1,800 calories a day and had meticulously tracked what they ate for at least two years, sticking to a mostly plant-based diet and consuming far less animal protein than the other group, a third fewer carbohydrates and only half the fat.

This calorie-restricted group, the researchers found, had a far richer and more diverse microbial community in the gut than those eating a typical American diet. They also carried several strains of “good” bacteria, known to promote health, that are unique to their plant-based diet. “Their choices as adults dramatically influenced their gut community,” said Nicholas W. Griffin of Washington University, the paper’s lead author.

The study, published in Cell Host & Microbe, is not the first to report findings suggesting dietary shifts can induce persistent changes in a gut microbial community, said Dr. David A. Relman, a professor of medicine, microbiology and immunology at Stanford University, who was not involved in the current research. He noted that other studies had found even more profound effects.

After the human microbiota was transplanted into the mice, the mice got to eat either like typical Americans or like the calorie restrictors.

Mice that had a microbiota conditioned by the typical American diet had a weaker response to the plant-based diet. Their microbial communities didn’t increase and diversify as much. “They all responded in a predictable direction, but with not as great a magnitude,” said Dr. Griffin.

Another aspect of the study suggests the company you keep may also enrich your gut microbiota — at least in mice. At first the animals were kept in separate cages. Then, when they were housed together, the microbes from the communities conditioned by plant diets made their way into the American-diet microbiome.

It’s not clear how that translates to humans: Mice eat one another’s droppings when they live together, so they easily share the bacterial wealth. Still, it’s possible humans have other ways of sharing bacteria, Dr. Griffin said. “We know from previous work and other studies that spouses who live together will develop microbial communities that are similar to each other,” he said.

Perhaps the best way to cultivate a healthier microbiome is to eat more fiber by consuming more fruit, vegetables, whole grains, legumes, and nuts or seeds, said Meghan Jardine, a registered dietitian who was not involved in the current study but has published articles on promoting a healthy microbiota. (She is also affiliated with the Physicians Committee for Responsible Medicine, which recommends a plant-based diet.) She urges people to aim for 40 to 50 grams of fiber daily, well above levels recommended by most dietary guidelines.

“When you look at populations that eat real food that’s high in fiber, and more plant-based foods, you’re going to see they have a more robust microbiota, with more genetic diversity, healthier species and fewer pathogenic bacteria living in the gut,” she said.

By RONI CARYN RABIN     DEC. 29, 2016