What Is IBS and How Do I Know If I Have It?

If you regularly experience bloating, abdominal pain, diarrhoea, constipation, a mixture of constipation and diarrhoea, or unpredictable bowel habits, you may have wondered whether IBS could be the reason.

With so much information available about IBS, food intolerances and gut symptoms, it can be difficult to know what is relevant to you. You may have received mixed messages about which foods to eat or avoid, tried changing your diet or taking supplements, and still be unsure what is contributing to your symptoms.

IBS can cause a wide range of symptoms, but similar symptoms can also occur with other gastrointestinal conditions. Getting a clearer understanding of what is happening is an important first step towards finding the right approach for you.

In this article, we’ll look at the common symptoms and different types of IBS, how IBS is diagnosed, what can influence symptoms and where diet may fit into managing them.

IBS is a disorder of gut-brain interaction, meaning there can be changes in how the gut and brain communicate. These changes can affect how the bowel moves and how sensations from the gut are experienced.

IBS does not cause visible damage to the digestive tract, but the symptoms are very real and can have a significant effect on everyday life.

For some people, symptoms are relatively mild. For others, IBS can interfere with work, eating out, exercise, travel and social activities, or create considerable uncertainty about what they can eat.

IBS symptoms can vary considerably from person to person. Some people experience abdominal pain or cramping, while for others, uncomfortable bloating, changes in bowel habits or urgency may be the symptoms they notice most.

Common symptoms can include:

• abdominal pain, cramping or discomfort
• bloating or abdominal distension
• diarrhoea or loose bowel motions
• constipation or hard bowel motions
• a mixture of constipation and diarrhoea
• changes in how often you open your bowels
• changes in the appearance or consistency of your bowel motions
• excessive gas
• urgency
• feeling that you haven’t completely emptied your bowels
• mucus in the stool

The combination and severity of symptoms can be different for everyone, and symptoms may also change over time.

Reflux can also occur alongside IBS, although it is not considered a defining symptom of IBS.

IBS can be grouped into four types based mainly on your usual bowel pattern.

IBS-C — IBS with constipation: Constipation is the predominant bowel pattern.

IBS-D — IBS with diarrhoea: Diarrhoea is the predominant bowel pattern.

IBS-M — IBS with mixed bowel habits: You experience a mixture of both constipation and diarrhoea.

IBS-U — unclassified IBS: You have symptoms consistent with IBS, but your bowel pattern doesn’t fit clearly into the constipation, diarrhoea or mixed categories.

Your bowel pattern can also change over time, so you may not always experience the same type of IBS.

There isn’t one blood test, scan or procedure that can confirm IBS. Your GP will look at your symptoms and medical and family history and may arrange tests to rule out other conditions. This may include blood tests and testing for coeliac disease.

The Rome IV criteria can also be used to help diagnose IBS. These include recurrent abdominal pain associated with changes in bowel habits. Other symptoms, such as bloating and urgency, are common in people with IBS but are not part of the formal diagnostic criteria.

The tests you need will depend on your individual symptoms and medical history.

Yes, they can.

Symptoms such as bloating, abdominal pain, constipation and diarrhoea can also occur with other gastrointestinal conditions, including coeliac disease and inflammatory bowel disease. This is why it is important to have ongoing symptoms properly assessed.

It is also important to consider coeliac disease before removing gluten from your diet, as starting a gluten-free diet before testing can make coeliac disease more difficult to diagnose.

If you have persistent, recurrent or changing gut symptoms that haven’t been medically assessed, speak with your GP.

It is particularly important to seek medical advice if you experience symptoms or changes such as:

• blood in your bowel motions
• unexplained weight loss
• iron-deficiency anaemia
• bowel symptoms that regularly wake you during the night
• a new or significant change in your usual bowel pattern
• a relevant family history, such as bowel cancer, inflammatory bowel disease or coeliac disease

These features don’t automatically mean that something serious is wrong, but they do mean that further assessment may be appropriate.

There isn’t usually one single cause of IBS.

IBS involves changes in the way the gut and brain communicate, as well as differences in how the bowel moves and responds to sensations. This can contribute to symptoms such as abdominal pain, bloating, constipation, diarrhoea and urgency.

Several factors can also influence IBS symptoms, including:

• food and eating patterns
• bowel habits
• stress and psychological wellbeing
• sleep
• physical activity
• hormonal changes
• changes in your usual routine

Some women also notice changes in their symptoms around their menstrual cycle or during other hormonal changes. These factors can affect people differently and may also interact with each other. For example, stress may influence symptoms for one person, while food, bowel habits or hormonal changes may be more noticeable for someone else.

This is one reason IBS can sometimes feel unpredictable. A food may seem to trigger symptoms on one occasion but not another because food isn’t necessarily the only factor influencing how you feel.

Yes, food can play an important role in IBS symptoms, but there isn’t one IBS diet that suits everyone. Rather than immediately cutting out foods, it can be helpful to look at your overall diet and eating patterns to work out what may be contributing to your symptoms.

Depending on your symptoms and usual eating pattern, this may include looking at:

• whether you are eating regularly
• meal size
• the amount and type of fibre in your diet
• fluid intake
• caffeine or alcohol, where relevant
• foods or food components that may be contributing to symptoms
• foods you may already be avoiding

Sometimes relatively simple changes can make a difference, while other people may benefit from a more structured dietary approach.

The aim is to understand your individual triggers, improve your symptoms and help you feel more confident about what you can eat, while keeping your diet as varied as possible.

The low FODMAP diet is an evidence-based dietary approach that can help improve symptoms for some people with IBS. FODMAPs are types of fermentable carbohydrates found naturally in many foods. For some people with IBS, they can contribute to symptoms such as bloating, abdominal pain and changes in bowel habits.

However, not everyone with IBS needs a low FODMAP diet, and it isn’t always the best place to start. When appropriate, the low FODMAP diet involves three stages: a short-term reduction in high FODMAP foods, followed by reintroducing FODMAPs to identify which you tolerate and which may trigger symptoms, and then personalising your diet.

The aim is to understand which FODMAPs affect your symptoms and how much you can tolerate, while including as much variety as possible.

You can read more in The Low FODMAP Diet for IBS: What Is It and Could It Help?

Once IBS has been diagnosed, nutrition support can help you understand how food may be affecting your symptoms and which changes are likely to be most helpful for you.

Depending on your symptoms and what you are currently eating, this might include looking at:

• your usual eating pattern
• fibre intake
• meal size and timing
• possible food triggers
• whether a low FODMAP diet may be helpful
• foods you are currently avoiding
• whether you are getting enough variety and nutrition from your diet

Food is also only one part of IBS management. Stress, sleep, movement, bowel habits and other factors can influence symptoms and may also be worth considering.

Nutrition support can help you put these pieces together and develop a personalised approach that helps manage your symptoms without restricting your diet more than necessary.

If you have ongoing gut symptoms that haven’t been medically assessed, a good first step is to talk with your GP. They can assess your symptoms and consider whether IBS or another condition may be contributing.

If you have been diagnosed with IBS and are struggling with symptoms, unsure what is triggering them or confused about what to eat, nutrition support can help you work through this.

With the right approach, you can better understand what influences your symptoms, identify what works for you and feel more confident about what you can eat.

Learn more about IBS nutrition support and how I can help.