The Colon Journal
A short course on the organ nobody taught you about.
Twenty-one chapters, in order, from where your food goes to why the last metre of your colon decides so much. No prior biology needed.
Fibre helps constipation.
The colon is an organ I never understood. Fibre is how I feed it.
Part 1
Meet your gut
Where food goes, what gets absorbed, and the one thing your body cannot break down.
By the end you will know which organ does what — and which one fibre is really for.
02 What actually gets absorbed?A short inventory of what your small intestine takes out, so you can see what it leaves behind.
03 Why humans cannot digest fibreThe reason is a bond your enzymes cannot read — and it is where the word prebiotic finally earns a...
Part 2
The forgotten organ
Why the colon is a fermentation chamber rather than a waste bin, and who lives in it.
Four jobs, only one of which is disposal — and why the slowest organ in your gut is slow on...
05 Meet your second digestive systemNot good bacteria and bad bacteria, but a workshop of specialists where one worker's output is the next one's raw...
06 What is fermentation, actually?Energy without oxygen, why gas is a by-product rather than a fault, and the one variable that decides comfort.
Part 3
What fermentation makes
Prebiotic, probiotic, postbiotic — and the short-chain fatty acids the rest of your body notices.
Three words used interchangeably that sit at three different points on the same pathway.
08 The three short-chain fatty acidsAcetate, propionate and butyrate are not variations on one theme. Where each one goes decides what it can do.
09 Butyrate: fuel for the colonYour colon lining runs on a molecule your microbes make — and burning it maintains the conditions for making more.
10 Your colon is not one placeFermentation front-loads at the caecum and thins towards the sigmoid. Why the far end is the interesting end — and...
11 When the fuel runs outBacteria that run out of fibre switch to protein. What that produces, where it happens, and what carbohydrate fermentation suppresses...
Part 4
Why diversity matters
No single fibre does every job. What follows from that, and what a designed spectrum looks like.
Solubility is one property out of four, and the only one on the label. Why two soluble fibres can behave...
13 Speed is a design variableRate decides where a fibre ferments and whether it feels like anything. Why gas is a rate problem, and why...
14 Who eats whatBacteria can only ferment what they carry enzymes for, and most butyrate is made in two steps by two different...
15 How to grade any fibreFour questions that work on every product on the shelf, each mapped to a mechanism — applied to Buta-8 as...
Part 5
The colon in daily life
Regularity, appetite, glucose, cholesterol, the gut lining — mechanism first, then honestly where the evidence stops.
Most of what fibre does for regularity is hold water where your colon would otherwise reclaim it.
17 Fibre, appetite and GLP-1Your densest population of appetite sensors sits at the far end of your gut, carrying receptors for the products of...
18 Glucose and the viscosity brakeThe one fibre effect with no biology in it — and why it only counts for the meal it is...
19 Cholesterol and the bile acid loopA gel traps bile acids so they leave instead of being recycled, and the liver pulls LDL from the blood...
20 The lining and the mucus layerThe barrier is a flow, not a wall. What bacteria eat when the fibre stops arriving.
21 What we still don't knowWhere the mechanisms stop predicting what will happen to you specifically — and which claims to be suspicious of, including...
Reference library
Shorter answers
Standalone pieces that answer one question directly. Not part of the reading order.