Constipation–diarrhoea continuum
Two problems that want opposite things, on one continuum.
Constipation and diarrhoea are usually treated separately, but many people swing between them — and that alternation itself is barely studied. The middle (IBS-M) is the least-researched part.
Go deeper
2 layers below. Open any one.Fibre and laxatives are trialled; the alternation is not. In the global burden lists the diarrhoea-leaning half is even filed beside Crohn’s and colitis while the rest sits under “other digestive” — so the alternating patient is split across two categories and disappears. Good evidence Constipation alone runs about 10–15% of people (Barberio 2021); the continuum has no clean figure at all.
The Akkermansia “hero strain” story did not hold up on closer reading. “Constipated patients don’t report gas” turned out to be methane being absorbed, not absent. And the pelvic-floor outlet and the microbiome are studied in separate literatures that rarely meet — two fields that rarely meet, which is why the connection gets missed.
Questions to bring
Copy these, or read them out. They fit in a short visit.
- Do I swing between constipation and diarrhoea — and is that treated as one problem or two?
- Is this an outlet (pelvic-floor) problem, a transit problem, or both?
The short version
- Getting ahead of it
- Fix the mechanics and feed the microbiome; do not just pile on fibre.
- Your testing regime
- Track with the Bristol chart, and distinguish slow transit from an outlet problem before anyone escalates laxatives.
- What they don’t tell you
- The alternation itself is barely studied, and “no gas” is methane absorbed, not absent.
- What it can spawn
- Haemorrhoids, diverticular disease and pelvic-floor injury — and it can mask colorectal cancer.
- What it’s confused with
- IBS labels, and an outlet problem called “constipation” and treated as slow transit.
From general clinical literature; not a diagnosis; nothing here comes from any individual’s medical record.