Next time you are viewing a chart of human anatomy in the doctor’s office, or in a medical textbook, pay special attention to the large intestine. It’s called ‘large’ because it is much bigger than the ‘small intestine’. In fact it is the largest abdominal organ. Its other name is the ‘colon‘. Given its size you might think it receives a lot of attention from those who look after our health, but you would be wrong. Similarly, it receives almost no attention from those who claim to understand human nutrition. This organ becomes important only when it it is the site of disease.

The colon is our secret garden where a multitude of friendly bacteria of many species break down the ‘indigestible’ parts of our food. These bacteria have evolved with us over hundreds of thousands of years and we tolerate them and benefit from what they produce through their digestive activity. The human colon is similar to fermentation organs in other animals in that it works best when we supply the bacteria with enough of the foods they need. Unfortunately, we have learned to produce and eat highly refined foods that are quickly digested in the small intestine, leaving little or nothing for the colon bacteria to deal with. We could talk about ‘fast’ and ‘slow’ foods. Fast foods, such as proteins, sugars, fats and prepared cereals are quickly digested and absorbed in the small intestine; while slow foods – fibres, seeds, nuts, fruit skins, whole cereals, etc. pass through into the colon and are broken down by friendly bacteria over a day or more. We have yet to identify fully all the products of digestion in the colon, and how they benefit us. There is evidence some of these substances affect the immune system and that others prevent diseases including colon cancer.

So to keep our friendly bacteria, and us, healthy, we need to eat ‘colon-friendly’ foods. And eat enough of them to keep the colon functioning properly. How will we know when the colon is working well? There is a reflex that links the stomach with the colon. When we eat a meal, the gastro-colonic reflex causes the colon, after about 20 minutes, to empty some of its contents, and these are passed as faeces through the anus. The regular need to visit the loo after each meal is the sign of a full and healthy colon, and a healthy colon is probably the best preventative of colon disease. Constipation is the sign of a neglected colon.

So the next time you visit a juice bar, ask them to throw away the juice – only water, sugars and flavour, but keep and eat the residue and explain you are looking after your colon. And, of course, keep well away from the ‘poo fairy’ and colonic irrigation!