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I was going to head this piece up as “Let’s talk about poo” but sensitivity just wouldn’t let me. But that is what we’re going to look at here. In a nutshell, the Bristol Stool Formation Scale (BSFS) is a simple graphic way of understanding how ‘well’ your poo/pooh/poop/faeces/stool/motions is/are.

Quite why ‘toilet talk’ sends many of us into fits of giggles is a bit of a mystery to me: at home, my family affectionately call me “The Poo Doctor”. At least, I think it’s affection. When we understand that “poo”, or whatever other name we give it, is the waste our body creates from the food and drinks we consume, digest and absorb, and then pass, I wonder why so many of us shy away from talking about it, preferring to confine it to the safe zone of toilet humour. Yet our poo can tell us so much about our health.

So, just what is ‘poo’?

Whatever we eat and drink has to be processed: digested, broken down, absorbed and eventually it’s tiny component parts end up in the bowel where they are combined together to make ‘poo’. Our poo contains fibre, water, bile, detoxified hormones and other metabolic products, and bacteria.

We are probably all familiar with the term ‘fibre’: way back in the 1970s, the F-Plan Diet, our attention was drawn towards fibre-rich foods as a useful tool in managing appetite and weight. These non-digestible carbohydrates come from plants and are ‘soluble’ or ‘insoluble’. While it’s tempting to focus on one or other, most fibre-rich foods bring both types to our body. Another type of fibre – ‘resistant starch’ – has come to our notice more recently, again in the weight management arena. Such starch is found in grains, legumes, potatoes and bananas amongst other foods; there are several types but the one that many of us know about is the sort that becomes concentrated when foods such as potatoes are cooked and cooled and then re-heated. This type of resistant starch may help us feel fuller for longer.

What does this mean for our poo? Quite simply, fibre supports an efficient transit time: poo passes through the gastrointestinal tract at an appropriate rate. This is important because a sluggish bowel may encourage poo to remain in the bowel for too long, with waste products such as detoxified hormones being re-absorbed through the gut wall and back into the bloodstream. Fibre also adds bulk: a softish, bulky pooh is easier to pass.

Poo also contains bile; produced by the liver, bile is involved in the digestion of fats and plays a part in the digestion and absorption of fat-soluble micronutrients such as the vitamins A,D, and E.

As well as fibre, water and bile, poo contains bacteria. The gut is home to about 100,000 billion bacteria and other micro-organisms: this flora and fauna is referred to as the gut microbiome. Waste material collects in the large bowel, or colon, where some 1,000 different types of bacteria – some helpful, others less so – live. As the waste passes along the large bowel, it picks up some of these bacteria and they are removed along with the other waste when we pooh.

Our gut bugs are central to our health: the appropriate balance is important. Some species create vitamin K and the water-soluble B vitamin group as well as metabolites such as butyrate that play a part in gut health. A healthy microbiome is now thought to contribute to reduced risk from certain infections, including Covid-19, and research studies are currently exploring whether a healthy microbiome enhances vaccination effectiveness. A transit time that is either too quick or too slow may contribute to an imbalance in the gut microbiome, with associated consequences for health.

How can we tell if our poo is ‘healthy’?

There are a couple of ways to check if our poo is healthy or if we need to make some changes.

First of all, we need to consider how often we ‘go’. Many of us will have a poo at least once a day; some vegetarians go more often, and some indigenous people such as the Masai, studied for their gut microbiome, go after every meal. While daily ‘bowel opening’ is considered healthy, keeping everything moving along nicely, many of us don’t ‘go’ every day: reasons may include stress, dehydration, low intake of fibre, or sluggishness due to medications.

Then we need to think about how urgently we need to go. The nerves in our bowel should be able to tell us it’s time to head towards the loo, but this should be a gentle nudge rather than a yell. We should be able to hold on for a little while; if we need to go immediately, something may be amiss. When we eventually do go, we should be able to produce something fairly easily without the need to spend a long time sitting. The need to spend a prolonged time ‘on the loo’ may be motivated by a need for privacy, time alone, or simply to read a book or the paper; if it’s motivated by a reluctant gut, some changes may be needed.

When we have a poo, the process should be simple, easy, and pain-free. If we have to strain to produce it or if it causes discomfort, it’s time to review our pooh. A sluggish bowel allows the water in our waste to be re-absorbed, creating dried out poo that’s hard to pass; an excited bowel doesn’t allow the waste to form into a poo-shape; a poo that’s been fermented by the microbiome may be quite explosive.

What this means is that the size, shape and consistency of our poo is a key indicator of its health.

This is the central idea behind the Bristol Stool Formation Scale (BSFS): it’s basically a chart that provides a quick reference to poo ‘health’. The BSFS was created by the team at Bristol University for clinical use by healthcare practitioners as a shorthand, embarrassment-free, tool in talking with patients, clients or fellow practitioners about poo. Yes: I do talk to my colleagues, friends and family about number 2s (and all the other numbers).

The Bristol Stool Formation Scale (with US spelling of ‘diarrhoea’):

This graphic comes from Cabot Health, Bristol Stool Chart – http://cdn.intechopen.com/pdfs-wm/46082.pdf

So, the BSFS is a simple way of categorising poo, but what does it all mean?

The ‘ideal’ is number 3 or 4. Number 1 or 2 suggests a sluggish bowel, whilst 6 or 7 suggest a rapid transit time. Number 5 indicates a lack of shape or bulk.

Number 1s are characterised by being hard to pass; looking like rabbit droppings, they show that water has been resorbed from the waste into the bowel. A number 1 can leave a sense of not having been ‘properly’, leading us to sit on the loo for an extended time (with or without a good book!) and cause additional problems.

Number 2s, whilst a little more formed and bound together than number 1s, are still considered indicative of constipation; like number 1s, they can also cause straining. Because they’re a little more formed than number 1s, they may cause abdominal discomfort and distension. Some people find their pooh fluctuate between 1 and 2.

Diet is often the culprit in these types of pooh: try increasing intake of water or other hydrating fluids every day and review intake of dietary fibre from fruit, vegetables and unpolished grains to add more bulk and softness. Do be careful increasing fibre if you experience IBS-C; some fibre may irritate the gut. If the situation doesn’t improve, review exercise. Any activity that uses muscles will involved the gut, which is basically a long muscular tube. If those approaches aren’t relevant, look at any medications as some of these can slow down the gut. Classic culprits like certain antihistamines can dry out the bowel, while others such as painkillers can slow down transit time. You may benefit from talking about this with your GP, especially if there’s a sudden change lasting for more than a few days – remember that the BSFS can make this conversation easier.

Number 3s and 4s can be considered as ‘healthy’. They’re well-formed, smooth and easy to pass, with a sense of complete evacuation. Other than a slight variation in surface appearance, they’re pretty much the same; the variation may be due to differences in water, fibre or fat content. No need to change anything here.

Number 5s are looser than 3s or 4s; they’re softer and may start out solid but then fall apart to become smushy blobs (yes, it’s a technical term). If short-lived, look at stress or eating something that didn’t quite suit you. If this lasts longer, and is unusual for you, get it checked out; it may be ‘normal’ for some or it may be related to IBS-D, increased intake of artificial sweeteners such as sorbitol or maltitol, or some other factor.

Number 6s are “loose”; they have some mushy content but are poorly formed and very squidgy around the edges. These could be the result of a diet that merits a review, an undiagnosed food intolerance or allergy, or linked to certain medications. Antibiotics are a particular culprit as they change the composition of the gut microbiome. If loose stools continue for more than a few days and there’s no obvious cause, it’s worth visiting your GP to exclude any other factors.

Unlike number 6s, number 7s are classic diarrhoea. Sevens have more watery content than 6s and, because they lack solid pieces, can exert pressure on the sphincter that result in accidents. Embarrassing yes, but over a few days, watery diarrhoea can result in dehydration. Electrolytes available over-the-counter may help; if it persists, speak to your pharmacist or GP.

Number 7s can be linked to medications, or to a functional health issue; they can be quite common when travelling to less-developed countries. I’ve had more than my share of Traveller’s Diarrhoea as I’ve explored Egypt and the Red Sea (makes SCUBA diving interesting!), India, and North Africa. The countries of South or Central America and the Far East are also notorious. Local medicines can be more effective than our products, but if health issues persist, particularly when you’ve returned home, you may have acquired an infection or something else: a chat with your GP or other gut-focused healthcare practitioner may be needed.

In summary, our poo may be ‘waste’ but it can tell us so much about our gut, and wider, health. Using the BSFS is a simple and easy way of assessing how your poo is doing, and takes less than a couple of minutes. Checking your poo is a great habit to create and, if you want to start conversations, try sticking a copy of the BSFS up in the bathroom. If nothing else, it’ll embarrass your kids!

Of course, if you’d like to learn more about your poo and how to make it healthier, I’m always happy to talk all things loo-related with you.

Stay well,


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