The brain is always 'on'. No breaks, even during sleep. However, the bottom line is it doesn't work for nothing - fuel is required. And it stands to reason that the fuel must be high quality for optimum physical and mental function. The minerals, vitamins and antioxidants required for such function are not miraculously conjured by the body, but are found in high quality nutritious diets. Findings from the field of nutritional psychiatry have demonstrated that 'traditional' Mediterranean and Japanese diets are associated with a 25-35% decreased risk of depression relative to a typical Western diet. Further, studies have shown that use of probiotics - which influence the colonisation of 'good' bacteria in the intestines - can have positive effects on perceived levels of anxiety and stress. It is generally agreed amongst professionals that processed and refined foods - so readily consumed today - may have detrimental effects on body and brain function, decreasing the regulation of insulin, promoting inflammation and oxidative stress. In this lecture, we will explore how different nutrients can affect the body and the microbiome. We will consider what happens when we remove dairy and wheat from the diet. We will also address how a 'clean' diet, free from processed foods and sugar but inclusive of fermented foods like kimchi, miso, sauerkraut and pickle might change physical and mental well-being. Feed your brain!