What are 'toxins' and how do we eliminate them?

In the first of his interviews, John Immel, Ayurvedic expert and founder of JoyfulBelly.com sheds light on ‘toxins’ - a word readily bandied about in the media - but what exactly are they and where do they come from? How do we recognise the build up of these toxins and how do we best support our body to eliminate them safely according to our body type?