Sadly, I don't mean eating crap like pizza and chips, washed down with a fizzy drink and a deep-fried Mars bar – that will certainly not save your life. I'm talking about poo. Real, stinking, human excrement. Your faeces is composed not only of what you had for dinner last night – don't pretend you haven't seen the unnervingly whole-looking pea or piece of sweetcorn floating in the toilet bowl – but also consists of other organisms, microbes to be precise. It may surprise you to learn that over half of the dry weight of your faeces is actually microbial. The average adult human is made up of approximately 10 trillion cells, yet is associated with over 100 trillion bacteria, collectively called your ‘microbiome’. Therefore by number (but fortunately not by mass), you're actually more microbial than human! Bacteria cover every inch of your skin and every orifice, but the vast majority live in your gut. These bacteria help digest your food, protect against nasty, disease-causing, bacteria and in return get a nice, warm, nutrient-rich environment in which to live. Until they come out the other end that is.

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