As humans, we live in symbiosis with both each other and millions of other organisms both around us and within us. Some microorganisms of these microorganisms are detrimental to our health and should be eradicated from our environment, whilst a huge proportion are beneficial to our health and well-being and should be nurtured.
The human digestive tract, particularly the lower intestines, host an enormous ecosystem of microorganisms, including viruses, fungi and bacteria which make up the gut microbiome. The huge surface area of the digestive tract is approx. 300 sq m (about the area of 2 tennis courts) and is the part of the body with the most direct contact with the outside world. The tract is incredibly susceptible to colonisation by a huge range of bacteria and the average human has at least 2 kg of bacteria in their guts alone. Most of the bacteria live in the lower digestive tract as the upper tract has contact with the stomach’ s digestive juices that are extremely acidic, and bile salts.
Initial colonisation takes place at birth as we pass through the vaginal canal of our mothers. As we are born, the bacteria in our mother’s body, mostly Bifidobactera, populate our gut. Those born by Cesarean section are exposed to skin bacteria instead so don’t get the benefit of populating their gut with beneficial bacteria during the birthing process. Whilst in adult life, 10% of intestinal flora are Bifidobacteria, through breast-feeding, 95% of all bacteria in the newborn’s gut are Bifidobacteria. Babies that are bottle-fed have less developed gut flora as they are less exposed to these beneficial bacteria and this can affect their immune system. As we grow older and develop, we are exposed to more bacteria via contact with different humans, animals and foods, the intestinal flora changes. Each person has their own unique microbial footprint. So far, the Human Microbiome Project(1) have identified about 1000 different species of gut microflora over many different phyla. This is a huge ecosystem within you, which is almost as diverse and dense as the Amazon rainforest. Balance within this ecosystem is influenced by our actions and this balance maintains biodiversity to create health and wellbeing. Imbalance reduces diversity and creates illness. Our intestinal bacterial flora are an essential component within our bodies which we cohabit. Our relationship with the microbiome is symbiotic - our bodies house the bacteria and provide food whilst the bacteria participate in our health in several ways:
Breakdown of complex carbohydrates– our bodies lack several enzymes to degrade plant fibres freeing up the sugars that fruit and vegetables contain which we can then use for an energy source.
Produce vitamins and minerals- the metabolic activity of intestinal flora leads to the production of vitamins K, B12 , niacin, pyroxidine and folic acid which we are unable to produce on our own (2).
Produce short-chain fatty acids– our gut flora ferment fibre to produce short chain fatty acids which are both an important energy source for the cells of our colon along with regulating the immune process, healing, reducing inflammation ad protection from cancer and other diseases.
Protect against pathogens– as the first line of defence, intestinal bacteria work by stimulating the immune response to protect against pathogenic bacteria. In addition, lactobacilli and bifdiobacteria can transform substances rich in fibre into lactic acid when there is no oxygen. Lactic acid acidifies our intestine and slows down proliferation of pathogenic bacteria.
Train our immune system– intestinal bacteria can selectively suppress the immune response so that we can tolerate some substances in our environment, which is important for preventing autoimmune disease and allergies. The bacterial genes can also regulate local and systemic inflammation (4).
Support detoxification– the gut flora are able to degrade toxic metabolites formed in the liver from metabolisation of our food. These metabolites are carried by the bile to the intestine, where the bacteria can degrade and safely eliminate them.
Regulate the nervous system– the latest research demonstrates a connection between our gut microbiome, digestive system, nervous system and brain. These interactions might influence everything from behaviour, mood, and appetite regulation (5).
Our gut microbiome is essential for balancing day to day body functions via both their metabolic activity and impact on the immune system. This system requires delicate balance to maintain optimal health and well-being and any imbalance could have a profound impact on our weight, health and quality of life. Imbalance of lack of biodiversity of the gut microbiome from nutrition and lifestyle choices could contribute to many diseases including including risk of cancer, type 2 diabetes, irritable bowel syndrome, cardiovascular disease, allergies, mood disorders and inflammatory bowel disease. If you would like to find out more about how your gut microbiome may have gotten out of balance and how to improve, please contact us for personal nutritional consultation or join one of the nutrition and cooking classes. 1. Peterson et al– The NIH Human genome project : Genome Research 2009; 19, 2317- 2323 2. Leblanc et al– Bacteria as vitamin suppliers to their host: a gut microbiota perspective: Current Opinion in Biotechnology 2013; 24, 160 - 168 3. Layden et al– Short chain fatty acids and their receptors: new metabolic targets: Translational Research 2013; 161–131-140 4. Ivanov et Honda– Intestinal microbes as immune modulators: Cell Host and Microbe 2012;12–496-508 5. Rhee et al– Principles and clinical implications of the brain-gut-enteric microbiota axis: Nature Reviews Gastroenterology & Hepatology 2009; 6–306-314