What exactly do microbiota and microbiome mean? Which parts of the body are included in the gut? What kinds of organisms call the gut their home? Why is the gut getting so much attention these days? Let us find out…


In this blog, we regularly talk about the gut and the trillions of bacteria that have a profound impact on our overall mental and physical health. But some of the scientific terms can get a little confusing. So, in this blog post, we explore the various technical terms used and understand their exact meanings and impact on the body. Let us start with some terminology and facts.


Gut - gastrointestinal system, also called the gastrointestinal tract, digestive system, digestive tract, or gut, is a group of organs that includes the mouth, esophagus, stomach, pancreas, liver, gallbladder, small intestine, colon, and rectum.

Microbiome - ‘Biome’ is an ecosystem made up of flora and fauna. ‘Micro’ indicates that this ecosystem is invisible to the human eye. Microbiome is made up of mostly bacteria, but also viruses, archaea (single-celled organisms), and fungi, which all play a role in maintaining the ecosystem’s stability. Gut microbiome refers to the genomes of microorganisms that reside in your colon.

Microbiota - they are a part of the microbiome, includes the different microbe populations present in the large intestine, including bacteria, archaea, and viruses. It has evolved alongside humans to get to where we are today, living in a mutually beneficial relationship.

Metagenome - The genes of microorganisms in a specific environment.


    • The human gastrointestinal (GI) tract is one of the largest interfaces (250–400 m2) between the body and the environment and the antigens in the body.
    • Average human gut weighs about the size of a mango and is about 7-10m long.
    • In an average lifetime, around 60 tonnes of food pass through the human GI tract.
    • 95% of the bacteria is in the large intestine making it one the most densely populated microbial ecosystems on the planet.
    • Composition of the gut microbiota is as personal and unique as a fingerprint. It is the door creating a barrier to keep out the pathogens.
    • Human genome consists of 23,000 genes whereas microbiome encodes over 3 million genes.
    • Human body contains 1:1 ratio of bacterial and human cells, i.e. we are as much microbes as we are humans, making us a superorganism.

    The gut does not offer as many biochemicals as some of the other environments in the body so the gut microbes must be adapted to certain lifestyles. In the gut, sources of energy are processes such as fermentation and sulphate reduction of dietary and host carbohydrates.

    The density and composition of the microbiota are affected by our diet, immunity and the chemicals found in the gut. Small intestines have lower microbiota because of high levels of acids, oxygen and antimicrobials, and a short transit time (time it takes for ingested food to travel through the human gut). In contrast, the colon (large intestine) has a dense and diverse community of bacteria with the ability to break down complex carbohydrates which are undigested in the small intestine.

    So it is safe to say that the food that we consume daily plays an important role in the diversity and density of the good bacteria in our body. The impact of the food consumed is seen within 24 hrs. Poor diet and lifestyle can drastically reduce the population of these bacteria, thereby impacting other organs and systems.


    Gut bacteria over a lifespan

    After birth, the GI tract is rapidly colonised, and life events such as illness, antibiotic treatment, and diet changes cause sifts in the microbiota.




    Influencing factors

    Birth – 2 years
    Rich and diverse microbiota, with dominance of Firmicutes and Bacteroidetes
    type of birth, type of feeding, genes, term vs preterm
    Stable gut microbiota with established colonies of bacteria
    diet, lifestyle, medications, antibiotics, exercise
    low diversity; enrichment of potentially harmful bacteria groups
    diet, lifestyle, medications, decline in body functions



    Gut Bacteria Types

    There are more than 1000 species of bacteria in the gut but we shall discuss the two main types that play a major role in probiotics – Bifidobacterium and Lactobacillus. Strains of these two types inhibit harmful bacteria, improve gastrointestinal barrier function, and suppress proinflammatory cytokines.





    Where is it found?  
    Primarily in lower GI tract (small intestine and colon). Small amounts also found in the vagina, mouth, and stomach
    Found in the digestive tract; make up over 95% of gut bacteria in a newborn and decrease over lifetime to about 25% in older adults
    What does it do?
    - maintain health of GI tract and immune system
    - break down lactose; reduce gas, bloating, abdominal pain
    - digest prebiotic fibers to produce beneficial compounds, including lactate and short chain fatty acid acetate, which both help maintain a healthy gut barrier*
    - inhibit growth of bad bacteria by producing anti-bacterial compounds called bacteriocins and reducing gut pH
     - help body fight inflammation; boost immune system
    - reduce gastrointestinal symptoms like bloating, abdominal pain, constipation.
    - protects gut barrier
    - breaks down starch into short chain fatty acids (SCFA), which help regulate multiple body functions
    - reduces diarrhea caused by antibiotic treatment or viral infections
    Foods that contain them
    - fermented milk products foods that contain this live bacterium, such as yogurt
    - prebiotic dietary fibers found naturally in foods such as onions, garlic, pulses, and bananas encourage growth of this strain
    - prebiotics found in plant foods such as grains, chicory, onion, berries, whole grains
    - probiotics rich foods like yogurt, kefir
    - fermented foods that have live organisms. Watch out for pasteurized products that may not contain any live organisms.
    *Gut barrier - (dynamic and semipermeable barrier that allows the absorption of nutrients, electrolytes while ensuring containment of undesirable luminal contents within the intestine)


    All this science talk proves that we need the presence of good bacteria in the gut to be healthy. The easiest way to improve our gut biome is through a balanced diet rich in fiber and fermented foods/drinks (such as sauerkraut, pickles, miso, certain types of yogurt, kefir, and kombucha).  Get in touch with your gut bacteria today, feed it some tasty kombucha and ferments and feel the best you can feel!


    Booch offers several fermented products in addition to our signature kombucha and jun drinks to help you strengthen your gut biome, and they are all made with fresh, organic ingredients sourced from local farmers.








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