Reading Your Stools: What Your Poo Reveals

One of my hometown's claims-to-fame, aside from the magnificence of the Clifton Suspension Bridge, is being the birthplace of the mighty Bristol Stool Chart.

This seven category scale, developed at Bristol Royal Infirmary, categorises poo across a spectrum - from hard pellets like rabbit droppings to brown water. According to the chart, the ideal stool is a mid-range type 4: "like a sausage, smooth and soft".

Smashing.

An early noughties TV programme on UK's Channel 4 featured a nutritionist who examined faecal samples in order to comment on people's health, looking at consistency, colour and smell. All I can say is that Channel 4 must have been paying her a significant wage to undergo that ordeal. Still, she was on to something.

While there's no need for dissection of your own faecal matter, there's no doubt that the colour and consistency of what's in the toilet pan or on the paper can give important information about the state of your health.

Fifty shades of brown

The average healthy poo is, of course, brown. In case you've ever wondered, it's the bile secreted by the liver into your intestines that stains faeces that fetching shade of burnt umber.

Stools are made up of indigestible material that cannot be absorbed into the bloodstream. This includes a solid component, consisting of proteins, fats, complex carbohydrates and fibre, as well as some of the bacterial colonies from the gut, and more - but it varies between individuals, according to their diet and microbiome.

Stools are mostly water, though: 75% on average. However, this also varies between hard, soft and fluid stools, which makes for many different recipes of poo - in a rainbow of browns. Dehydration - when your body's losing more fluids than it's taking in - can lead to hard stools which are difficult to pass. On the other hand, diarrhoea can lead to an increased loss of fluid and cause dehydration.

So, if you're experiencing either constipation or very loose stools it's important to ensure you drink plenty of water to stay well hydrated.

Changes in colour

Stools can be stained many other colours - and the causes range in their prevalence and their severity.

Take green stools for instance - possibly a result of eating green veg or food containing blue dye. Certain bacteria, such as salmonella, may stain stools green. Bile, which is a dark green in colour, may be more easily seen in conditions causing rapid movement of faeces through the bowel and diarrhoea, such as a viral infection.

You'll also be able to tell from the appearance of your stool whether your body is unable to release bile into the gut - because of problems such as gallstones, and liver and pancreas disorders (including cancer) obstructing the bile ducts. Since one major role of bile is the dispersal and breakdown of fats, less bile means less fat absorption, and more fat accumulating in the stool, giving them a pale yellow, white or oily/greasy appearance. Increased fat in stool is also called steatorrhoea.

A red stool is an alarming sight. It can indicate bleeding from many different regions of the gut, from haemorrhoids to cancer of the colon. Blood changes in appearance as it moves through the gut, so may appear as either bright or dark red, and either mixed in, or coating the outside of the stool.

If there is an abnormality with upper regions of the gut (the gullet or stomach) - a bleeding ulcer for instance - then blood passes into the chyme (the soup of digested food). This alters its appearance to produce a black, shiny and sticky stool which resembles tar. It also has a distinctive, foul odour. We call this malaena and, because it signals heavy bleeding, it's a medical emergency.

Red or black stools can also be caused by foods and dietary supplements, such as beetroot or iron and charcoal tablets. However, any variations in stool appearance such as red, dark/black or fatty yellow-white stools should always be taken seriously and reported to a doctor as soon as possible. Large amounts of red bleeding, or black, tarry malaena require an emergency visit to hospital.

Baby poo

At a newborn baby check, parents are always asked by a paediatrician whether their little one has had a wee and a poo before they're allowed to head home. You're unlikely to have missed their first poo. Anyone who's had a baby and changed their nappy for the very first time knows that the initial experience is an … interesting one.

The first stool a baby produces, which they have been banking up in utero, is dark, sludgy and green and called meconium. Baby's first poo is made up of old dead cells, mucus and bile. One saving grace is that it doesn't smell.

Meconium (thankfully) disappears with the start of milk feeding. Stools of breast milk-fed babies have a characteristic mustard-like appearance and smell tends to be associated with formula-fed kids. Baby poos vary in colour, consistency and volume as the bowel develops, and with weaning.

Sometimes my daughter produced such astonishing poonamis that she had to be cut out of her baby grows. It's all part of the rich tapestry of parenthood.

Dan Baumgardt does not work for, consult, own shares in or receive funding from any company or organisation that would benefit from this article, and has disclosed no relevant affiliations beyond their academic appointment.