More and more research is showing how important the health of the gut is to physical and mental wellbeing and the number of papers published on the subject has grown exponentially; now thought to be around 75,000. The bacteria, yeast and viruses that live in our gut are called the gut microbiome and there are around 100 trillion of them. Many of these microbes are beneficial and even essential to human health, while others can be harmful. This symbiotic relationship benefits microbes and their hosts as long as the body is in a healthy state. Sometimes dysbiosis develops when the more harmful bacteria get to overwhelm the system leading to ill health (Medical News Today, 2023). By reducing factors that harm the good microbiome and increasing factors that help it to be restored to the right balance, much can be done for wellbeing. This two-part article explores why a good balance of microbiota is important and what factors encourage a healthy microbiota and what factors cause an imbalanced one. It is in two parts because it is now such a vast and popular subject; with this first part exploring why the gut microbiome is so important for health and wellbeing and what an unbalanced microbiota (otherwise known as dysbiosis) can lead to.