The environment contains numerous microbial communities within the soil, water and in and around our homes. Most living organisms are associated with them, with the human body resembling an ecosystem, working in symbiosis with a myriad of microbes – effectively a super-organism. With over 100 trillion microbes, collectively known as the microbiota, these outnumber our own cells ten to one, making us only 10% human. The microbiota contain 4.4 million genes, compared with our human genome of merely 21,000 and the collective genes of our microbiota collaborate with our own genome to ensure efficient running of our bodies, with gut bacteria believed to be the major influencers to our health. Microbiota is as unique as our fingerprints, even in identical twins, changing throughout life.
Microbes live on our skin, in our mouths, ears, nose, vagina and entire digestive system, comprising bacteria, archae, protozoa and fungi species.
During digestion, nutrients are absorbed into the bloodstream, to be utilized throughout the body. The gut bacteria then perform functions that our human genes cannot, such as fermenting indigestible fibre, converting it into useable molecules, maximizing the availability of the remaining nutrients and releasing it as energy. Efficiency of calorie storage and control of gut inflammation are also part of their responsibilities.
Diversity of the microbiota is proving to be a crucial factor in our health, with each different community performing a specific role, however this diversity is often not as extensive as it should be due the modern Western lifestyle.
The gut-brain axis is a bi-directional communication system, involving the brain, central nervous system (CNS) and the gut environment. The vagus nerve is a neural pathway running from the brain stem to the abdomen and is an integral part of the enteric nervous system (ENS). Messages are passed to and from the brain and gut via the ENS and through the vagus nerve, the sympathetic system and the bloodstream. Our immune system is central to our health and its relationship to gut microbiota is growing increasingly evident. Germ-free animals born and raised under strict sterile conditions, have a deficient intestinal immune system because of the lack of microbes.
Four main groups of bacteria have been identified as representing over 90% of our gut microbiota;Firmicutes, Bacteroides, Proteobacteria and Actinobacteria. The Firmicutes and Bacteroides are mainly responsible for digesting food and metabolizing any drugs that we take. Three main clusters are being referred to as “enterotypes” which are dominated by Bacteroides, Prevotella and Ruminococcus. These are associated with specific metabolic features and have strong links with long term diet.
Certain microbes have been linked to chronic diseases such as obesity, IBD, heart disease, MS, autism and colon cancer with suggestions that a lower diversity in gut microbial communities overall is significant.
Helping Our Little Friends
Probiotics are live organisms that can benefit health. They are found naturally in the gut microbiome and produce anti-microbial compounds, keeping harmful bacteria at bay by competing for nutrients and prebiotics. Probiotics can be taken as a supplement and occur in fermented foods such as yogurt, sauerkraut, kefir, cheese, and kimchi. Fermented foods are estimated to have been part of our diet since around 10,000 BC.
Prebiotics are indigestible carbohydrates that reach the colon intact and selectively feed many strains of beneficial bacteria. Prebiotics can be divided into three different types: non-starch polysaccharides; soluble fiber; and resistant starch. Most prebiotics are ingested by bifidobacteria and help to stimulate the growth of healthy gut microbes and inhibit the growth of pathogens.
Incorporating both probiotics and prebiotics into our diet can help to maintain healthy gut microbiota, thereby minimising the risks associated with diet and lifestyle. Sauerkraut, kimchi, live yogurt, kombucha and kefir are all easy ways of adding probiotics and eating plenty of fresh fruit and vegetables and safe starches, such as cooked and cooled potatoes, wild rice, green bananas will help keep your little gut friends happy and healthy, so that you will reap the benefits.