Did you know that there is a poo scale? No, neither did I, until I read Enders’ bright and breezy book. ‘Bright and breezy’ might seem odd adjectives for a book about defaecation, about Enders’ fascination with what happens to what goes in at our mouths and out of our bottoms is both charming and enlightening – and renders the whole subject much more palatable (sorry!).

So the poo scale, known as the Bristol Stool Scale and only developed in 1997, divides poo into seven categories, with number 1 being little, hard rabbit pellets and number 7 dirty brown liquid with no solid bits, and all the variations in between. Ideally, we should be producing type 3 (‘sausage-shaped but with cracks on surface’) or type 4 (‘sausage- or snake-like, smooth and soft’) poos. Not only did I learn about types of poo but that the best way of expelling them from one’s bottom is, in fact, to squat. Sitting on a toilet produces a kink in the bowels that the bowel muscles have to push past where squatting smoothes out the bowel interior and enlists gravity. So the squat toilets that are still found in some Asian countries are better for defaecating while also producing a helpful hip flexion.

Apart from poo, the book goes into the extraordinary gut flora that live inside us – we are all, it seems, an ecosystem as much as individuals – and the fundamental ways in which the guts affects our health. These connections are only just being teased out but it appears that all sorts of conditions are made better or worse by our insides. It appears that the old adage that you are what you eat is truer than we ever realised.

An entertaining and informative book – and what more could you ask of a book about poo.