Gut Health 101: What Is the Microbiome?

An image of bacteria. The Microbiome is the set of genes of the bacteria living in our bodies.

The microbiome is often confused or equated with the microbiota, but they are two different things. The microbiota is the collection of beneficial, benign, and pathogenic microbial cells housed in and on the human body.[1] The microbiome refers to the complete set of genes within these microbes. Estimates place the number of these microbial genes to human genes at a ratio of 100:1.[2] Microbial genes significantly influence how your body operates.

The human body is an incredibly complex, interconnected microbial ecosystem, and each of us has a unique microbiota and thus a unique microbiome. The microbes that colonize our bodies are determined by what we’ve been exposed to over the course of our lives and these colonies are constantly in flux. Geographic location, weather, illness, disease, medical treatments, stress, injuries, diet, gender, age, occupation, hygiene, and everything you touch all affect the composition of your microbiota.[3]

Public Health, Germ Theory, and the Microbiome

Scientists have known about microorganisms for hundreds of years. In 1673, Antony van Leeuwenhoek wrote to the Royal Society of London about his discovery of tiny “animalcules” with the use of his “microscopes.” Leeuwenhoek found microbes almost everywhere he looked,[4] but they were largely ignored until the 1870s when their role in the cause and spread of disease was observed. Previously, doctors believed that bad air caused disease, but Robert Koch proved that tiny microorganisms were responsible for diseases such as cholera, anthrax, and tuberculosis. This discovery solidified the validity of germ theory, the idea that certain microbes are the source of specific diseases.[5]

There were definite benefits to the establishment and proof of the validity of germ theory. For one, doctors and surgeons started washing their hands and sanitizing tools and instruments.[6] New laws led to public health initiatives to contain and prevent illness. They were very successful at limiting the spread of pathogens, disease, and saving lives.[6] The scientific rationale for cleanliness was the precursor to it becoming a moral and social imperative.

People began bathing daily. Soap, once considered a luxury, became a basic household necessity. Microorganisms were rigorously and thoroughly vilified as agents of disease and sources of filth for decades. Scientists and researchers realized that many of these microorganisms we’re so keen to eliminate are actually beneficial to our health.[7]

The effects of the microbiome on the body are just beginning to be explored and understood. Until recently, scientists focused primarily on how pathogenic microbes affected us and how to stop them. More attention is now dedicated to the microbiome and its integral role in our health and immunity.[8] Launched in 2008, The Human Microbiome Project (HMP), began analyzing the microbiota of the nose, bowel, vagina, skin, lungs, and nasal passages. The goal of this project is to better understand the relationship between health, disease, and the microbiome.[9] For as long as there have been humans, we have lived with microorganisms in and on us, and we’ve evolved alongside one another to form a symbiotic, cooperative relationship that allows us both to thrive.

The Makeup of the Microbiome

Our microbiota is comprised of a dizzying number of microorganisms—bacteria alone make up the bulk of these at about 30-50 trillion bacterial cells,[10] whereas the human body itself only contains an estimated 37.2 trillion human cells.[11] It may be disconcerting to think of yourself as mostly microbial cells, but don’t worry. By weight, you’re definitely mostly human. Microbial cells like bacteria, archaea, fungi, and viruses are significantly smaller than human cells. To provide context, bacterial cells range from 0.2-10 microns (micrometers) across, while human cells range from 10-100 microns.[12] For reference, the average dust mite, which is microscopic, is 200-300 microns wide.

If you’ve seen the oft-quoted 10:1 ratio (10 microbes to 1 human cell), you might be surprised to learn that it was actually just an attractive guess that became widely circulated throughout academic and scientific resources until it was believed to be fact. It is now regarded as academic urban legend.[13] However, it’s important to note that the microbes in the microbiota could exceed the 10:1 ratio if you account for all of the viruses, archaea, parasites, and fungi.

Bacteria in our intestines.

We carry around an estimated 3 pounds of bacteria in our intestines.[14] Everyone’s microbiome is as unique as their fingerprint and comprised of hundreds of different types of bacteria.[15] A person’s bacteria cell count varies throughout the day and is always turning over.[16]

Viruses are the most abundant inhabitants of the human ecosystem,[8] but bacteria account for most of the mass of the microbiota. Viruses don’t have the cellular machinery to reproduce and must hijack the genetic code of other cells, like bacterial or animal cells, to create more copies of themselves.[17] We tend to think of viruses as harmful invaders, but that’s not always the case. The viruses found in our gut are primarily bacteriophages, meaning that they infect the bacterial cells in our guts, but not necessarily at the expense of our beneficial bacteria. The two microbes seem actually to have a symbiotic relationship in our guts. Viruses are an excellent means of quickly transferring genes, and they’ve been observed carrying genes that are beneficial to their host bacteria’s survival. So if you introduce new beneficial bacteria to your gut, either through diet or probiotics, the viral cells in your intestines can help this bacteria thrive by introducing new genes into the bacterial genetic code.[18]

The Role of the Human Microbiota

The role of the microbiome is so central to the body’s everyday and lifetime operations that it essentially acts as a sort of organ.[18] Our microbiome impacts the rate at which we mature, our digestion, immune function, metabolism, and even mood, and cognitive function.

Some of the bacteria in our gut produce enzymes that form an essential part of our digestive system. The human body can easily digest simple sugars, but struggles with the larger polysaccharides, the healthy and complex sugars in our diets that we get from plant foods.[19] These bacteria also provide our systems with B vitamins, vitamin K, and short chain fatty acids. Some of the cellular products our microbiota product also influence the rate of our metabolism.[20]

Recent research finds that a well-functioning bacterial microbiome is the foundation of your immune system. You were born with a sterile gut at birth, but with your first meal, your gut’s microbial education began.[21] Exposure to microbes trains the immune system how to respond to different organisms. In this way, the immune system essentially mediates the relationship between the body and the microbes it hosts.[21] Harmful organisms are dealt with, helpful organisms, like microbiota, exist in harmony with the immune system and contribute to good health overall.[22]

Further, some research reveals the important role our microbiome plays in our mental health. There is a complex relationship between your gut and brain, called the gut-brain axis, or GBA. The microbiota interacts with your central nervous system, and certain bacterial strains have demonstrated the ability help regulate your brain chemistry. These interactions mediate stress responses, anxiety, and the even function of your memory.[23]

How Is the Human Microbiota Formed?

A baby's microbiota.

Researchers disagree whether babies are wholly free of microbial activity before birth, but most agree that the human body is exposed to some of its first microbes during the birthing process.[18, 24] The makeup of the maternal vaginal microbiota actually changes during pregnancy.[25] Babies born vaginally are colonized primarily by the Lactobacillus genus of bacteria. Newborn babies delivered by Caesarean section are exposed and populated by skin microbes, such as Staphylococcus, Corynebacterium, and Propionibacterium.[26] Even the composition of the babies microbiota can be different depending on if they are born in a hospital or at home.[3]

As babies continue to grow and have new experiences, their microbiome will change. In the first few months of life, the body is colonized by relatively few species of microbes—only about 100. By the age of 3, the microbiota of children possesses closer to 1000 microbe species and begins to resemble the microbiota of an adult. Two significant periods of change in the microbiota are puberty and menopause, during which there are major shifts in microbiota composition.[3]

The Bacteria in Your Gut Microbiome

Microbiome composition can change throughout the intestines. The bulk of these microbes are found in the large intestine where they ferment the food your body is unable to digest, such as complex carbohydrates and fiber. The bacteria in the average adult gut are most likely Bifidobacterium, Lactobacillus, Bacteroides, Clostridium, Escherichia, Streptococcus, and Ruminococcus. Your diet, including the microorganisms in your food, determines the microbial composition of your microbiota. Further, the makeup of our microbiota influences the nutritional value of our food based on their cellular operations.[27] Research reveals that, though the specific bacteria may vary, many of the genes the housekeeping found in these beneficial bacteria are the same.[28]

Since we’ve always had these bacteria to help us digest our food into nutrients the human body can absorb and use, we never developed the genes to produce the enzymes required to break down these complicated molecules. These bacteria enable us to eat a more diverse diet and get a broad range of micronutrients and phytonutrients.[29]

Supporting the Microbiome

Your microbiome is constantly being updated by the new microbes you expose yourself to via your diet.[1] It’s important to cultivate the right microbiota in and on your body because we rely on their genes for essential processes and to help prevent infection or overpopulation from pathogenic microbes.

To shape your microbiome for the better and keep these beneficial microbes healthy, eat a diverse diet rich in complex carbohydrates and fiber.[30] You can also try probiotics to shape your microbiota, and to further support the health of their colonies, try adding prebiotics, which are oligosaccharides that feed your probiotic strains.

I personally recommend FloraTrex™ for a healthy microbiome. It contains both prebiotics and 23 different live, active probiotic strains that were chosen to support your digestive health, mood, and promote a balanced microbiota.

Have you tried prebiotic or probiotic supplements before? Tell us about your experience in the comments!

References (30)
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The post Gut Health 101: What Is the Microbiome? appeared first on Dr. Group’s Natural Health & Organic Living Blog.



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