Gut Bacteria And The Brain: Are We Controlled By Microbes?

Although the interaction between our brain and gut has been studied for years, its complexities run deeper than initially thought. It seems that our minds are, in some part, controlled by the bacteria in our bowels.

The gut has defenses against pathogens, but, at the same time, it encourages the survival and growth of "healthy" gut bacteria.

The vast majority of these single-celled visitors are based in the colon, where no less than 1 trillion reside in each gram of intestinal content.

Estimating the number of bacterial guests in our gut is challenging; to date, the best guess is that 40 trillion bacteria call our intestines home - partially dependent on the size of your last bowel movement (poop's major ingredient is bacteria).

Read more: Gut Bacteria And The Brain: Are We Controlled By Microbes?

How much sway can a microbe hold? Bacterial influence over human psychology is slowly coming
into focus.

Source: medicalnewstoday

The Mucosal Immune System: Master Regulator of Bidirectional Gut–Brain Communications

Communication between the brain and gut is not one-way, but a bidirectional highway whereby reciprocal signals between the two organ systems are exchanged to coordinate function. The messengers of this complex dialogue include neural, metabolic, endocrine and immune mediators responsive to diverse environmental cues, including nutrients and components of the intestinal microbiota (microbiota–gut–brain axis). We are now starting to understand how perturbation of these systems affects transition between health and disease. The pathological repercussions of disordered gut–brain dialogue are probably especially pertinent in functional gastrointestinal diseases, including IBS and functional dyspepsia. New insights into these pathways might lead to novel treatment strategies in these common gastrointestinal diseases. In this Review, we consider the role of the immune system as the gatekeeper and master regulator of brain–gut and gut–brain communications. Although adaptive immunity (T cells in particular) participates in this process, there is an emerging role for cells of the innate immune compartment (including innate lymphoid cells and cells of the mononuclear phagocyte system). We will also consider how these key immune cells interact with the specific components of the enteric and central nervous systems, and rapidly respond to environmental variables, including the microbiota, to alter gut homeostasis.

Key points

• Common gastrointestinal diseases, such as IBS, functional dyspepsia and IBD, are closely linked to psychological morbidity
• This link is driven in part through bidirectional signaling between the brain and gut, which reciprocally regulate each other
• Growing evidence implicates the importance of immune activation, which might be overt (IBD) or more subtle (IBS, functional dyspepsia) in pathological gut–brain interactions
• The composition of the intestinal microbiota affects behaviour and mood, which could in part rely on selective activation of distinct host cytokine responses
• Therapeutic targeting of gut microorganisms, host immunity or psychological symptoms could hold the key to uncoupling pathological interactions between the gut and brain

Read more: The Mucosal Immune System: Master Regulator of Bidirectional Gut–Brain Communications

Key brain–immune–gut interactions

Source: Nature Reviews: Gastroenterology & Hepatology

Antibiotics In Early Life Could Raise Children's Food Allergy Risk

Infection in the first year of life can be deadly for an infant, and antibiotic treatment is often the first port of call. But such treatment may have a downside; new research from the University of South Carolina finds early antibiotic exposure could raise a child's risk of food allergies.

While the study did not investigate the reasons behind this association, the researchers say it is likely down to changes in gut microbiota as a result of antibiotic treatment.

Lead author Dr. Bryan Love, of the Department of Clinical Pharmacy and Outcomes Sciences at the South Carolina College of Pharmacy, and colleagues report their results in the journal Allergy, Asthma & Clinical Immunology.

Previous research has suggested that changes to the composition of gut bacteria in early life can have negative implications for health, and antibiotics are known to do just that.

Read more: Antibiotics In Early Life Could Raise Children's Food Allergy Risk

Early antibiotic exposure could raise children's risk of food allergies.

Source: medicalnewstoday

High-Fat Diet in Pregnancy Reduces Beneficial Gut Microbiota for Offspring

Eating a high-fat diet during pregnancy could alter the population of gut microbiota in offspring, which may have negative implications for nutrition and development. This is the conclusion of a new study published in the journal Genome Medicine.

It is well established that what women eat and drink during pregnancy can influence the health and development of their child.

For example, it is recommended that expectant mothers consume 0.4 milligrams of folic acid every day in order to help prevent certain birth defects, and current advice says a healthy, balanced diet is best for both mother and baby.

Read more: High-Fat Diet in Pregnancy Reduces Beneficial Gut Microbiota for Offspring

Women who eat a high-fat diet in pregnancy may be putting their offspring's health and development at risk,
say researchers.

Source: medicalnewstoday

Breast milk hormones found to impact bacterial development in infants' guts

Intestinal microbiome of children born to obese mothers significantly different from those born to mothers of healthy weight

A new study finds that hormones in breast milk may impact the development of healthy bacteria in infants' guts, potentially protecting them from intestinal inflammation, obesity and other diseases later in life.

The study, published Monday in the American Journal of Clinical Nutrition, examines the role of human milk hormones in the development of infants' microbiome, a bacterial ecosystem in the digestive system that contributes to multiple facets of health.

"This is the first study of its kind to suggest that hormones in human milk may play an important role in shaping a healthy infant microbiome," said Bridget Young, co-first author and assistant professor of pediatric nutrition at CU Anschutz. "We've known for a long time that breast milk contributes to infant intestinal maturation and healthy growth. This study suggests that hormones in milk may be partly responsible for this positive impact through interactions with the infant's developing microbiome."

Researchers found that levels of insulin and leptin in the breast milk were positively associated with greater microbial diversity and families of bacteria in the infants' stool.

Read more: Breast milk hormones found to impact bacterial development in infants' guts

A new study examined the role of human milk hormones in the development of infants' microbiome

Source: ricardoferrando/Fotolia

Gut microbes regulate nerve fibre insulation.

Far from being silent partners that merely help to digest food, the bacteria in your gut may also be exerting subtle influences on your thoughts, moods, and behaviour. And according to a new study from researchers at University College Cork, your gut microbes might affect the structure and function of the brain in a more direct way, by regulating myelination, the process by which nerve fibres are insulated so that they can conduct impulses properly.

The surprising new findings, published today in the journal Translational Psychiatry, provide what is perhaps the strongest evidence yet that gut bacteria can have a direct physical effect on the brain, and suggest that it may one day be possible to treat debilitating demyelinating diseases such as multiple sclerosis, and even psychiatric disorders, by altering the composition of the gut’s microbial menagerie in some way or another.

Gut microbe research has exploded in the past 10 years, and in that time, it has become increasingly clear that there is a two-way line of communication betweengut bacteria and the brain. The human gut microbiome seems to play important roles in health and disease, and alterations in its composition have been implicated in a wide range of neurological and psychiatric conditions, including autism, chronic pain, depression, and Parkinson’s Disease, although the links still remain somewhat tenuous.

Read more: Gut microbes regulate nerve fibre insulation.

Scanning electron micrograph showing E. coli bacteria.

Source: Wikimedia Commons