So having accepted that not all of you is you, and that the colon bacteria assist in the breakdown of substances in human foods which cannot be digested in the small intestine, what are the implications of this partnership? Let’s start with the colon itself, which is an integral part of you. This is the largest organ in the abdomen, and so one presumes it must be important. It has evolved to provide a home for the bacteria and to assist in the slow breakdown of the colon foods – let’s call this ‘fermentation’. So the function of the colon has evolved to include an activity in which it contracts into temporary pockets or bulges which serve to mix the contents forwards and backwards.

Fermentation of the contents of the colon results in the production of soluble substances and gas. The latter is voided, as you well know, through the anus. Even the most eminent amongst us fart! But what about the other products of fermentation? This is where our ignorance is supreme. We know very little about what the bacteria produce and even less about how they affect us. As the colon is well supplied with blood vessels, these substances are absorbed and carried throughout the body. If, as we know, the association between us and our friendly bacteria is very ancient and long-standing, the substances they produce are likely to be important in human health. Research is starting to show connections between the colon bacteria and the immune system, for example. Perhaps some common human illnesses are the direct result of a lack of the substances which the bacteria produce, because of our poor diet (See next blog on how to keep the colon healthy).

But how does the colon work? Because of our diets of highly refined foods, most digestion occurs in the small intestine and little indigestible material passes into the colon. However, when our friendly bacteria are well fed (see next blog) the colon is full of fermenting material. There is a reflex which links the stomach with the colon, so that when we take in food, this triggers an emptying movement in the colon. Food in faeces out. So it is normal to want to visit a toilet 20 minutes to half an hour after a meal. Furthermore, the colon and its bacteria keep working all night while we sleep, so it is normal to want to poo when we wake up. Absorption of fermentation products from the colon while we are asleep may be the most important aspect of our association with our friendly bacteria. Sleep is our time of recovery for more than one reason.