Friday, September 29, 2023

How Does The Human Microbiome Affect Our Health

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Role of Microbiome: How Does It Affect Our Brain and Behavior

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As Ed Yong says in his book I Contain Multitudes, The immune system is not innately hardwired to tell the difference between a harmless symbiont and a threatening pathogen its the microbe that makes that distinction clear.

The human microbiome even affects how we smell. Different microbe species might convert sweat into the smell of onions, or testosterone into the stink of urine, which act as strong signals for our friends and foes.

These smells are highly personal: studies have found people can be identified just from their sweaty T-shirts.

Scientists also think that our microbiome may be a significant contributor to why we get jetlag.

The change in sleep patterns puts the rhythm of our gut bacteria out of sync with our own behaviour, so different species are active at the wrong times.

Read more about the body and microbiome:

Effects Of Vitamins On The Microbiome

The human gut microbiota contains bacteria that are beneficial to the host, and bacteria with pathogenic potential, termed pathobionts . An important role of beneficial bacteria is the metabolic production of SCFAs by cross-feeding . Fiber-degrading bacteria include Ruminococcus callidus, Ruminococcus albus, Blautia obeum and Prevotella spp. which produce solubilized oligosaccharides and polysaccharides that act as substrates for butyrate-producing species such as Faecalibacterium prausnitzii, Eubacterium rectale, Roseburia spp, Eubacterium hallii and Anaerostipes spp . Butyrate has multiple effects on the host including maintenance of gut barrier function by stimulating the production of mucin, antimicrobial peptides, and tight-junction proteins and reducing colonic oxidative stress . These effects on gut barrier function are important for health as changes in the mucosal barrier have been described in IBD .

A picture of the Gram-stained cells of Faecalibacterium prausnitzii growing in a colony inside agar seen as a big ball at the left lower corner, chains of cells grow away from this colony . A typical single cell has the size of 35;µm in length and 1;µm in diameter. The bar represents 10;µm

Foods That Support A Healthy Microbiome

Foods that will support your gut health, and in turn help your microbiome function properly include fermented foods, such as miso , fermented dairy like yogurt and kefir, sauerkraut, fermented pickles, tempeh and Kombucha .

Raw foods are another great choice, especially those that are also high in fiber. Many of the microbes in our gut are designed to ferment soluble fiber. Choose legumes, fruits and vegetables, which all provide soluble fiber that will help nourish the lining of your colon.

One food to avoid is sugar; sugar actually makes fungi grow in the gut, which will produce yeast infections and sinusitis.

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Why Is Gut Health Important

Before we talk about its importance, lets quickly share what we mean by the gut. To put it simply, our gut is one long tube that starts from our mouth, continues down to the stomach, our small and large intestines, and finally ends in the anus. There’s a fascinating world of ‘good’ micro-organisms that live throughout our gastro-intestinal tract, which are indispensable for its healthy function .;;

On the surface, it may seem that this organ system is only responsible for processing and digesting our food. After all, thats what we learned from our school textbooks.

While its truethat the guts duties include breaking down food and drink, assimilating nutrients, and pushing out the indigestible bits via the excretory system, science has finally started uncovering just how important our gut health is to several critical functions of our body.;

Studying The Gut Microbiota

How does the gut microbiome effect our brains?

Twin studies have shown that, although there is a heritable component to gut microbiota, environmental factors related to diet, drugs, and anthropometric measures are larger determinants of microbiota composition.45

Gut microbes are key to many aspects of human health including immune,6 metabolic5 and neurobehavioural traits .78 Different levels of evidence support the role of gut microbiota in human health, from animal models910 and human studies.4111213

Schematic representation of the role of the gut microbiota in health and disease giving some examples of inputs and outputs. CVD=cardiovascular disease; IPA=indolepropionic acid; LPS=lipopolysaccharide; SCFA=short chain fatty acids; TMAO=trimethylamine N-oxide

Animal models can help identify gut microbes and mechanisms, though the degree to which findings translate to humans is unknown. In humans, observational studies can show cross-sectional associations between microbes and health traits but are limited by the inability to measure causal relations. The strongest level of evidence is obtained from interventional clinical studiesin particular, randomised controlled trials.

The composition of gut microbiota is commonly quantified using DNA based methods, such as next generation sequencing of 16S ribosomal RNA genes or whole genome shotgun sequencing, which also allow inference of microbiota functions.1415 Metabolic products of the microbiota are now measurable in stool and serum using metabolomic methods.16

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What Is The Microbiome And How Does It Affect My Health

The human microbiome is the personalized collection of microorganisms and molecules found in our bodies. The microbiome is becoming recognized for its influences on everything that has to do with our health, from allergies to obesity.

The human microbiome is considered to be the counterpart to the human genome, which is all of our genes. However, the genes in our microbiome outnumber the genes in our genome by as much as 100 to 1.

Preemptive Strike: Type 2 Diabetes In Its Early Stage

Type 2 diabetes is nearing epic proportions in the world and is closely linked to the rising epidemic of obesity. Ten percent of the US adult population has T2D, and another 30% are prediabetic. Prediabetes is a health condition where a persons blood sugar levels are elevated, but not sufficiently high enough to warrant a T2D diagnosis. This happens because both prediabetic and T2D individuals usually suffer from insulin resistance, where the body no longer responds to the hormones signals to move glucose out of the bloodstream and into cells. Almost 70% of the prediabetic population will become diabetic in their lifetime.

The iHMPs third model system, the Integrated Personal -Omics Project , led by Michael Snyder, Ph.D., Stanford University, and George Weinstock, Ph.D., Jackson Laboratory for Genomic Medicine, was formed to answer fundamental questions such as: what causes the progression of prediabetes to T2D? What stressors during the prediabetes state increase the risk of such a shift?

The IPOP study recruited 106 healthy and prediabetic individuals, who were studied over a period of four years. Their gut and nasal microbiomes, as well as biological factors of both host and microbiome were followed over those four years.

To start with, researchers found that healthy participants had different gut microbiome makeup than those with prediabetic symptoms, thereby already setting up these prediabetic patients with a possibly diminished or unhealthy microbiome.

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Types Of Intestinal Bacteria

There are four main types of intestinal bacteria that live within the human gut. They are the phyla Firmicutes, Bacteroidetes, Actinobacteria and Proteobacteria.Bacteroides make up 30% of the human gut flora, suggestion they are particularly important to host health.The relationship between these bacteria and host is symbiotic.

While people can survive without gut flora, they provide many useful functions to human health. And the imbalance of any the above mentioned groups of bacteria can have a great impact on the well being of the host.

One Health Relationships Between Human Animal And Environmental Microbiomes: A Mini

Happy Gut, Happy You-The gut microbiome: How does it affect our health?
  • 1Department of Environmental and Occupational Health Sciences, School of Public Health, University of Washington, Seattle, WA, United States
  • 2Division of Biological Sciences, School of Science, Technology, Education, and Mathematics, University of Washington, Bothell, WA, United States
  • 3Health Sciences Library, University of Washington, Seattle, WA, United States

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Digestion And Food Breakdown

Until recently scientists believed that the human body was fully responsible for digestion of food but it turns out the bacteria in our gut plays a large role in what we are able to eat and digest. Bacterial enzymes in our gut can break down complex sugar other food molecules into fuel. These bacteria can also produce vitamins in the body, making them more essential than previously realized.

What This Means For Treatment

In terms of using interventions directed at the gut to treat brain disorders so called psychobiotics there is a lot of promise but little clear evidence.

Probiotic treatments in mice have been shown to reduce cortisol, an important stress hormone, and decrease anxious and depressive behaviours.

But there are very few studies in humans. A recent systematic review of all the human studies showed the majority do not show any effect of probiotics on mood, stress or symptoms of mental illness.

On the plus side, large studies show us that people who eat a balanced diet with all the usual good stuff have lower rates of mental illness as adults and adolescents.

Clearly, diet affects both the gut microbiota and mental health. Research is ongoing to see whether it is a healthy gut microbiota that underlies this relationship.

A healthy gut microbiota is linked to a healthy brain. However there are only a handful of human studies demonstrating real-world relevance of this link to mental health outcomes.

There is still a way to go before we can say exactly how best to harness the microbiota in order to improve brain function and mental health.

Read the other articles in our Gut series here.

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How Intestinal Barrier Functions Works

The intestinal wall is the primary interface between the gut microbiota and our body. It acts as a dynamic barrier that isolates our body from gut microbes but allows desirable interactions to take place. The intestinal barrier is made up of physical and chemical elements. The physical barrier is created by the epithelial cells that line the gut, the molecules on their surface, and the mucus they produce; the chemical barrier is created by inflammatory molecules , antibodies, and antimicrobial substances produced by epithelial and immune cells.;

Epithelial cells recognize microbial products via immune receptors known as pattern-recognition receptors . Activation of PPRs enables a dynamic adjustment of epithelial activity based on chemical signals from the microbiota. This allows epithelial cells to adjust their antimicrobial response to eliminate pathogenic infections, destroy infected cells, and influence the composition of the gut flora. Proper PRR signaling is important for the maintenance of tolerance to good microbes, for the elimination of intestinal infections, and consequently, for the maintenance of a balanced gut microbiota.;

Epithelial cells also respond to metabolites produced by the gut microbiota, such as short-chain fatty acids , polyamines, and amino acids. SCFAs, for example, serve as energy sources for epithelial cells, modulate their metabolism and their secretions, and help support the integrity of the epithelial barrier.

How Do Microbiota Benefit The Body

The Microbiome: How it is Important in Health and Disease

As noted earlier, this area of research is still relatively new for scientists; its only been in recent decades that they are beginning to understand the true potential scope of these gut bacteria and all the roles they might play in our health. However, there are several established benefits of microbiota:;

Defense against pathogens: One of the ways microbiota protect us from pathogens is by fully colonizing the spaces they inhabit; by having taken up residence in our gut and by utilizing the available nutrients, they leave little room for foreign microorganisms to thrive. Also, many microbiota release enzymes or other compounds that destroy or impair the ability of pathogens to reproduce or affect our internal systems.;

Intestinal development: Our digestive microbiome forms quickly after we are born, usually within one or two months. It is during this time that the epithelial lining forms in our bowels and begin to secrete a protective mucosal barrier that is friendly to beneficial microbiota. This intestinal lining and the microbiome develop simultaneously and ultimately benefit from each other in the process.;

Synthesis of important nutrients: Human cells are unable to produce all nutrients necessary for proper function, so many must come from external sources. But even then, external sources arent always sufficient. Microbiota are capable of synthesizing some important nutrients such as vitamin K, vitamin B12, short-chain fatty acids , and many others.;;;

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Why The Gut Microbiome Is Crucial For Your Health

Your body is full of trillions of bacteria, viruses and fungi. They are collectively known as the microbiome.

While some bacteria are associated with disease, others are actually extremely important for your immune system, heart, weight and many other aspects of health.

This article serves as a guide to the gut microbiome and explains why its so important for your health.

What Are Prebiotics And Probiotics

Dietary amounts of protein, saturated and unsaturated fats, carbohydrates, and dietary fibre influence the abundance of different types of bacteria in the gut. The microbiota can also be modified by adding live micro-organisms to food or by periods of fasting.

  • Probiotics are live bacteria and yeasts that, when administrated in a viable form and in adequate amounts, are beneficial to human health. They are usually added to yoghurts or taken as food supplements.

  • Prebiotics are defined as a substrate that is selectively used by host micro-organisms conferring a health benefit. Although all compounds considered prebiotics are microbiota accessible carbohydrates or fermentable dietary fibre, the reverse is not true. The prebiotic concept is an area of current debate70

  • Synbiotics contain a mixture of prebiotics and probiotics

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The Human Microbiome: Why Microbes Could Be Key To Our Health

The thought of bacteria living inside us is perhaps repugnant, especially since most people grow up being taught that germs are bad; some people even have deeply ingrained phobias about the germs all around them. Yet this truth about the useful presence of bacteria in our bodies has become much more popularly known in recent years, and more people than ever before are aware of the need for gut health and its connection to the proper functioning of our digestive systems.;

The research on this topic is still somewhat nascent, but studies are increasingly showing that these helpful bacteria are beneficial beyond just digestive health. Indeed, the symbiotic relationship with the bacteria present throughout our body may very well be the key to our overall health and wellbeing. The term for this collection of bacteria is the microbiome, and the more we understand about the microbiome, the more we as a species may be on the way to better health and longer lives.

Diseases Related To Overnutrition

Our Microbiome – Health Matters

More than half of the worlds adult population is overweight or obese, and the related conditions of diabetes and cardiovascular disease are now the leading causes of death globally . The rise of these conditions has been particularly rapid in minoritized populations , and it is unclear why individuals and populations vary in susceptibility when faced with similar diets and environments . Factors such as stress and sleep disruption, cesarean births, and early life antibiotics have been implicated .

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Preterm Birth And Neurodevelopmental Trajectories

Despite technology-enabled increases in the survival of extremely preterm infants in the United States, cognitive outcomes in these individuals are often severely impaired . Preterm babies born into low-SES families and/or minoritized populations often have poorer cognitive outcomes . While a number of factors, including access to early life education , likely contribute to these patterns, variation in inflammatory markers in infant serum is a key area of interest .

How Can The Indoor Microbiome Affect My Health

Human beings encounter microorganisms every day, and those microorganisms can have neutral, adverse, or beneficial effects depending on the person, their health, the microorganism, and many other variables. For example, some microorganisms or their products are linked to allergies or asthma, but exposure to some microorganisms early in life may also protect against asthma and recurrent wheeze in children. Much remains unknown about the direct and indirect connections between humans and the indoor microbiome. Many ongoing research projects aim to understand the interactions between microbiomes, the indoor environment and human health.

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How Do Microbes That Live In And On Us Affect Our Health Development And Even Behaviour

Microorganisms cover our skin and fill our guts. These bacteria, viruses and fungi collectively called the human microbiome were until recently only considered interesting if they led to disease.

But a growing body of research shows that a properly functioning microbiome has tremendous impact on human health. For instance, the ability to maintain a healthy weight is probably influenced significantly by the microbiota in your gut. A mothers microbiome could affect the healthy development of her fetuss brain. And researchers are learning about the effects of colonization on human groups by examining the microbes in dental tartar of human remains in West Africa.

This program brings anthropologists, biologists and other scholars together to provide biocultural context to host-microbiome interactions. Theyre asking new questions about what aspects of individual and societal behaviour are critical to understanding the role of the microbiome in human health and development.

Path to Societal Impact

We invite experts in industry, civil society, healthcare and government to join fellows in our Humans & the Microbiome program for in-depth, cross-sectoral conversations that drive change and innovation.

Leaders from public health schools and CIFAR fellows in the Humans & the Microbiome program are working together to develop new public health curricula.

Areas of focus:

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