Gut Microbiome and human health
How does the gut Microbiome influence human health?
How does the gut microbiome influence health? Most people think of the gut as the stomach on its own, but the gastrointestinal tract begins from the mouth through the oesophagus, stomach, small intestine, colon, and rectum to the anal sphincter. Each of these parts has a different role in health, including transportation, digestion, absorption, and elimination of the ingested substances to provide our bodies with crucial nutrients for life.
The gut microbiome consists of various microorganisms living in a mutually beneficial relationship with the human body. On good days! They call this a symbiotic relationship with the host. It is important to mention that gut microbiome and gut microbiota are used interchangeably, although they mean different things. Microbiome refers to the microorganisms and their genes, whereas microbiota refers to the microbes themselves.
We are unique…
Our nutritional demands and the make-up of our gut microbiome are as unique as our appearances. No two individuals share the same microbiome, just like our fingerprints. Therefore, understanding the correct amount of nutrients we need is the first, and possibly, the most critical step towards feeling vibrant and energetic. This article aims to examine how the gut microbiome affects human health and diseases.
What we currently know
According to more recent research, the human-bacterial ratio stands at 1:1, which means we have about the same number of bacteria in our bodies as human cells. Older theories claimed that bacteria outnumber human cells.
As new-borns, we are sterile, so the diversity of microorganisms depends on the environment at the time of delivery and feeding, the mother microbiome pre and postnatal, and antibiotics use. The adult gut flora is developed by the age of 3 years. Some stay with us till the end of our lives; others undergo rapid transitions. As a result, the microbial strains we house differ between environments and populations. For example, digesting seaweed by Europeans is more challenging than by Asian people.
What is the hype about these tiny creatures?
Beneficial bacteria metabolise nutrients and drugs for us, protect us against pathogens, modulate and train the immune system, produce short-chain fatty acids from fibre, produce vitamins, and support the structural integrity of the gut mucosal barrier. When something goes wrong with the microbes, something goes wrong with us too! Westernisation, urbanisation, and the increased consumption of processed foods and exposure to antimicrobial drugs result in the development of dysbiosis.
Dysbiosis, an imbalance of microorganisms in the intestines, has been associated with many debilitating diseases, including inflammatory bowel disease (IBD), irritable bowel syndrome (IBS), diabetes, and allergic conditions. Obesity is also very relevant. In the dysbiotic gut flora, the harmful microbes overtake the beneficial ones and manifest in various digestive complaints such as bloating, flatulence, diarrhoea, and constipation. Additionally, harmful bacteria release endotoxins which compromise the integrity of the intestines leading to permeability. The long term consequences of dysbiosis lead to more systemic issues in other parts of the body, such as the nervous, endocrine, and immune system.
Over 70% of the gut microbiota lives in the large intestine.
The predominant species are Firmicutes and Bacteroidetes. The Firmicutes: Bacteroidetes ratio gives us an indication of the risks of obesity and IBD. Sometimes bacteria dislocate in larger quantities into the small intestine, resulting in small intestinal bacterial overgrowth (SIBO).
An old and common way to prepare food is by fermentation, a natural process of the microorganisms converting sugar and starch into alcohol and acids in the absence of oxygen. For example, short-chain fatty acids (SCFAs) are produced by bacterial fermentation from non-digestible dietary fibre. Fibre increases the diversity of the gut microbiome and increases intestinal motility, reducing the number of gas-forming bacterial species. The microbes also use prebiotics, plant material and proteins that are non-digestible or can’t be broken down by us due to the lack of enzyme or issues with absorption to produce metabolites.
The three major SCFAs are butyrate, acetate, and propionate. The number of carbohydrates, intestinal gasses, and the pH of the colon are the main factors that influence their production.
Why are SCFAs so important?
Because they are heavily involved in energy metabolism, appetite regulation, gut motility, and neurotransmitter production, which affect our mood and relaxation. Depression, social behaviour, and cognitive function are also affected. Evidence suggests that there is bi-directional communication between the gut and the brain via the vagus nerve. Healthy individuals with a healthy gut mostly feel happy, energised, and looking forward to the day.
Feeding with fermentation
Our gut loves fermented foods such as yoghurt, kimchi, sauerkraut, miso, and tofu. They contain probiotics which are the beneficial bacteria themselves. Prebiotics are plant fibre that are feeding the good guys. The intake of both of these offers health benefits to the host only if consumed in adequate amounts. Carefully evaluating the appropriate strains and mixture is crucial for a compromised gut. For example, individuals with histamine dysregulation issues may worsen their condition by ingesting certain bacterial species as they further stimulate histamine production.
So, how does the gut microbiome influence health? While we know that the composition of the gut microbiota has a significant role in how we feel, research in this area and the immune system presents more open questions than any other aspects of human health. It is undeniable that dietary pattern has a pivotal role in the gut microbiota composition. Unhealthy food choices in the long term create an environment for and invite harmful microbes to thrive.
Author: Anita Andor, nutritional therapist