While arguably easier to clean up, the drier stool forms (types 1 and 2) tend to compact into large stool that can apply long term pressure to and abrade the lining of the large bowel.
During a bowel movement, dry stools may distend the anal canal beyond its normal aperture. This may require straining – and pain – to pass.
Straining to pass dry stools increases the risk of laceration of the anus, haemorrhoids, prolapse and the condition diverticulosis. This is when pouches form on the wall of the large bowel due to over-distension. These can become sites for infection or inflammation.
As a rule, softer but not watery stool forms are best.
Any change of bowel habit that leads to the sustained production of drier stools and a sense of incomplete emptying – or watery stools and a feeling of urgency – should be discussed with your doctor.
Why does water matter?
Even to the casual toilet bowl observers among us, the most obvious differentiating factor between stool forms is their water content.
The large bowel is an amazing recycling and repurposing centre for the body. Water recycling is one of its key functions.
Every day, our bodies invest around 9 litres of fluids into the digestion of food, including around 1.5 litres of saliva, 2.5 litres of stomach secretions and 0.8 litres of bile. But clearly we don’t defecate anywhere near this volume.
The longer it takes for digested food to pass through the large bowel, the more water gets reclaimed and the drier the stool becomes. So factors affecting the transit rate of food through our gastrointestinal tract will have significant influence on stool form.
Affluence and lifestyle impact on transit time. Antibiotics, pain killers (particularly opiate-containing drugs such as Endone but also more common pain-killers containing codeine) as well as physical inactivity all reduce how well the gut contracts. This slows the passage of food through the large bowel, which can lead to constipation.