Poo is always brown – and other gut health myths
8 things you didn’t know about your bowels, with expert insight from Professor Tim Spector.
Image credit: Shutterstock/Evtushkova Olga
8 things you didn’t know about your bowels, with expert insight from Professor Tim Spector.
A 2023 survey of 2,000 people by healthcare provider Benenden Health found that only 60% of UK adults would feel able to speak to a doctor about consistent problems with their poo.
The findings highlight that embarrassment and a lack of awareness could mean medical conditions are being ignored. Gut health myths could be contributing to this.
“There’s so much nonsense about gut health out there,” says Alana Macfarlane, champion for gut health and co-founder of digestive health business The Gut Stuff.
Alongside her twin sister Lisa Macfarlane, Alana presented the Channel 4 TV show Know Your Sh!t, which drew on the knowledge of medical experts to dispel myths and break the poo taboo in Britain.
Know Your Sh!t: Inside our Guts features a first-of-a-kind clinic. People with bowel problems visit the aptly-named Poo HQ each week to gain advice from a team of medical experts, who help them achieve better gut health.
The show aims to tackle the poo taboo in Britain and bust myths, as well as providing lifestyle tips to improve gut health. The light-hearted and accessible programme is available on All4.
Below, we’ve compiled a list of the common myths that Know Your Sh!t busted.
We’ve also spoken to world-leading expert in gut health Professor Tim Spector – who researched the Macfarlane twins’ gut microbiome at King’s College London and also appears in the Know Your Sh!t series – to help you understand your digestion and get to the truth about gut health.
Incontinence can affect people of any age
Bowel incontinence or faecal incontinence is an inability to control bowel movements. While it’s true that it’s more common in older people, it can affect people of any age.
Spector explains there are many different causes of faecal incontinence. He says these include infections, chronic inflammatory bowel conditions and dysfunctional bowel as a result of chronic constipation.
“It’s not inevitable with age and it does occur in young people and people with diseases,” he adds. Some people may have developed bad habits over time, says Spector, resulting in their muscles and nerves becoming ‘lazy’.
Doing targeted exercises or yoga to help strengthen the pelvic floor muscles can help to treat faecal incontinence for some people. But Spector says that if you develop bowel incontinence: “You should get a medical opinion and not just assume it’s old age.”
Sleep-deprived DJs turned gut health champions, Lisa and Alana Macfarlane, otherwise known as The Mac Twins, began their gut journey when they volunteered to be part of the TwinsUK research at King’s College London.
After sending off poo samples and undergoing a couple of colonoscopies (an examination of the bowel with a camera on a thin tube), they became the ‘chief guinea pigs’ for the British Gut Project.
The results inspired them to help spread the message about how important and exciting your gut is by setting up digestive health business The Gut Stuff. They have since become presenters of the recent Channel 4 TV series Know Your Sh!t and are developing an app.
How and when you eat matters too
This widely-known phrase has even influenced the names of TV programmes and books. It’s true that the food you eat can affect aspects of your health from weight to nutritional status (a person’s health condition shaped by their intake of nutrients) and possibly even mood.
But it’s not just what you eat, it’s also how you eat that matters. As well as swallowing more air, Spector explains that people who eat fast tend to gain weight and have bigger appetites and fewer healthy gut microbes.
When you eat may also matter. We are beginning to learn about the effect of time-restricted eating on the gut. This is a type of intermittent fasting, which involves restricting all food to a certain ‘window’ during the day. Spector says:
“Twenty studies explored eating within a specific time window, such as within 10 hours, and resting for 14. They have shown this reduces your appetite, improves your energy and improves your gut health.”
These small habits can all promote healthy digestion:
The British Dietetic Association has tips on eating mindfully – an approach to food that focuses on being fully present when eating, without distractions, which can promote healthy eating habits.
The condition is real and dietary changes can help to manage it
As the TV show made clear, people with irritable bowel syndrome (IBS) are often told it’s all in their minds. It is true that IBS is a condition that involves the gut-brain axis (a two-way communication system between the gut and the brain) and scientists are increasingly finding links between gut health and mental health .
But the symptoms of IBS are very real and include bloating, abdominal pain or discomfort and diarrhoea or constipation, or a mixture of both.
“Not everyone with IBS is depressed or anxious or has an obvious psychological disturbance,” says Spector. He adds that, despite being associated with anxiety and depression, IBS can partly be managed by diet and probiotics, which are thought to restore the natural balance of bacteria in the gut.
A specific diet proven to help with symptoms of IBS is the low FODMAP diet. This involves limiting foods which are high in FODMAPS – certain types of carbohydrates that are hard to digest – before re-introducing them. There are apps available for download that guide you through this, including the Monash University Low FODMAP diet.
The gut microbiome is the trillions of microorganisms (bacteria, viruses and fungi) that live in your digestive tract. Scientists are still learning about our microbiome, but it’s estimated that each person has around 1,000 species of bacteria in the gut.
Many other factors can also play a role
As the programme highlighted, many factors, from pets to stress and sleep, can affect your gut health. Research even shows links between gut and heart health. Something in particular surprised the Macfarlanes.
Despite people on the show having a broad range of gut conditions, mental health often played a big part. This points to the gut-brain axis once again. For this reason, much of the advice on the show wasn’t limited to diet. Alternative treatments included gut-directed hypnotherapy, yoga and breathing techniques.
Spector says it’s mainly diet that affects gut health, but other factors play a role as well. He says, for example:
“Dog owners have more diverse gut microbes than people without dogs. So do regular gardeners compared to people who never go outside or garden.”
This is because people with dogs or those who garden are regularly exposed to a wider range of microorganisms.
He explains that gut health starts to decline rapidly in your 70s, so making healthy lifestyle choices becomes even more important as you get older. Personalised nutrition app ZOE can help you with this.
Tim Spector is a Professor of Genetic Epidemiology at King’s College London, director of the Twins UK study, co-founder at health science company ZOE, and one of the world’s leading researchers in gut health.
He’s also the author of several books, including Food for Life (Amazon, £10.99), focusing on nutrition and health. He trained originally in rheumatology and epidemiology.
Poo can vary in colour – and it can tell you a lot about your gut
What colour should poo be? As explained on the show, it turns out, poo can be many colours, not just brown – and they can provide signs about our gut health. Common colours can include green, yellow, red, black and pale or chalky.
Digestive charity Guts UK has created a guide to checking your poo and understanding what the different colours might mean. Brown stool is considered normal and can vary in shade.
Poos of these colours can be harmless but if you are concerned about the colour of yours or notice blood or any other changes in your poo, speak to a health professional.
Spector explains that as we get older our poo colour can change, mainly because of changes in diet or the ability of the microbes in the gut to break down fats. Storing more fat can change the colour, he says.
Spector adds that changes in the length of time it takes for food to travel from one end of the digestive tract to the other can play a role in poo changing colour as you age. The digestive tract starts at the mouth and ends at the anus. He says increasing constipation associated with older people can also be cause.
This is why the poo taboo in Britain matters – because it is a key obstacle to discussing changes in our stools. Spector agrees:
“The British don't like talking about bowel movements. When I worked in France and Belgium,” he adds, “the first thing patients wanted to tell the doctor was what their stools look like or show pictures. This openness about your bowels and habits was just part of going to see the doctor.”
It is more accessible and achievable than you may realise
Something the Macfarlanes are keen to communicate is that anyone can make changes to improve their gut health. Lisa Macfarlane says many people perceive gut health as a middle-class luxury, with expensive and inaccessible solutions and products.
Within Know Your Sh!t, she says it was important not only to show the simple swaps to support your gut health – some of which you may already be doing and just need to do more regularly – but that a lot of them are very affordable, if not free.
Spector adds: “100 years ago we all had good gut health and evolution was designed to give us this. We’ve only recently lost this – we’ve lost 50% of our gut species in the last 50 years. So, it’s not some amazing state we’ll never achieve; it’s something we all had and a few per cent of the population do have it.
“Unless you have a really severe inflammatory disease or surgery, it should be available to you.”
We share some easy and accessible gut health tips.
Unique gut microbes mean everyone’s gut health is different
The Macfarlanes, who are identical twins, are living proof that everyone’s gut microbiome is different. Alana Macfarlane says:
“Lisa and I have 100% the same DNA, but we only have 30–40% of the same gut bacteria. So, we can’t do the same thing to look after our gut health.”
What makes each person’s gut health distinct?
“Your unique gut microbes,” says Spector. “Unlike our genes, which are not identical but are very similar, our microbes are very different.”
This means what works for one person might not for another. Why not try out the Macfarlanes’ very own The Gut Stuff diary (Amazon, £10) to record how your diet and lifestyle habits influence your gut and truly know your gut?
Chocolate with 70% cocoa or more supports helpful gut bacteria
Great news for chocolate lovers… Like most foods, it should be eaten in moderation, but dark chocolate can promote the growth of beneficial gut bacteria. This is thanks to the polyphenols (natural antioxidant compounds found in plants) it contains, which Spector explains are “like rocket fuel for your gut microbes”.
“Dark chocolate is a fermented bean. So, it comes from a plant,” he adds. “But we need to eat varieties that contain maximum cocoa and minimum milk and sugar.”
He says the benefits start to occur in chocolate above 70% cocoa solids, meaning you won’t get the same effects from most British chocolate, which contains less cocoa than that. Spector suggests eating one or two small squares of 70% or 80% dark chocolate regularly to reap the benefits.
Find out about other surprising gut-healing treats.
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