A really interesting programme on the microbiome and how important an influence it has on our brain and the development of chronic disease:
"Recent DNA analysis by the Human Microbiome Project detailed the vast and diverse array of microbes in and on our body - bacteria, archaea, fungi and viruses. It has been described as our second genome - a source of huge genetic diversity, a modifier of disease, an essential component of immunity, and an "organ" that influences not just our metabolism but also our mental health"
(28 minutes)