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Runners Tummy or IBS?

Runners tummy, IBS, the Trots, the runs (!). Whatever you want to call it, having problems with your poo when you run is common. My first ever article I wrote in 2014 was for Athletics weekly and was called " Running to the Loo". It was the most read article on line that year. My most searched for tag on my website at the moment is "runners tummy". I believe the reason for this is that many people are not comfortable taking about their bowel habits. They therefore search on line for answer to their problems.

I have treated many athletes that have suffered from runners tummy. I am also pleased to say that most have been very successful. As a sports dietitian, we can not only guide you to better performance but we are also clinically trained. All of us would have spent a minimum of 5 years in clinical practice in the NHS before specialising.

For this blog I am lucky enough to have a dietitian that is one of the countries leading practitioners in gut health. I have selected the most common questions clients ask me and put them to Dietitian Kirsten Jackson who specialises in Gastroenterology (the gut). If anyone has anymore questions we can do a part two blog!


Hi Kirsten, can you tell us a little bit about yourself and what you do?

My name is Kirsten Jackson and I am a Consultant Specialist Gastroenterology Dietitian and Founder of The Food Treatment Clinic.

After qualifying as a registered dietitian, I soon became interested in the area of gut health when I was diagnosed with Coeliac Disease myself.

I started my career in the NHS, but soon realised that there was a huge need for a more intense and supportive approach for people going through digestive problems like me.

In 2015 I opened the Online Clinic with the ethos of providing individuals with that intense level of support they need to understand and then control their symptoms. I found that by taking a holistic approach to gut health, we were able to get amazing outcomes that our clients really deserve.


What is IBS?

Irritable Bowel Syndrome or ‘IBS’ is a type of chronic, functional bowel disorder. We don’t know 100% yet what causes the condition but it is thought that there are several elements such as mental health, a sensitive gut, infection and food intolerances.


Is runner’s tummy different to IBS or the same thing?

Runners tummy is different to IBS. Runners tummy is the nickname given to the effect running can have on some individuals digestive system’s.

Just like IBS, we actually don’t know what causes runner’s tummy for sure. It is thought to be multifactorial, with a large physiological element.

During exercise, we know that there is an increased activity of the sympathetic nervous system. This sends more blood to the muscles and away from organs in order to provide the increased requirements. Unfortunately, this affect results in the gut slowing down, reduces the gut’s ability to absorb nutrients and increases the permeability of the gut, all of which can lead to digestive symptoms Stuempfle & Hoffman (2015)

This affect that the sympathetic nervous system has during exercise is only amplified in exercise which is more physically demanding e.g. further and or faster.


Once a runner has had a bad experience with their stomach, anxiety increases that it will happen again. Are there any known coping strategies to reduce anxiety occurring?

Having had a bad experience of runners tummy once can create anxiety around the potential of runners tummy happening in the future.

Race days are especially prone for anxiety triggering, where stopping to use the toilet could forfeit your race or there could be a potentially embarrassing situation with an audience present!

The problem is that this anxiety build up could actually cause digestive symptoms on its own.

Anxiety contributes to runners tummy through the ‘gut-brain axis.’ When our body is in a state of stress, we release hormones and nerve signals to help ‘run away from danger.’ However, these hormones and nerve signals can also be passed down the axis and cause you to run to the toilet.

There are several known ways to help manage anxiety and it is important to always bare in mind that if this is a continual issue for you, you need to speak to your doctor

In terms of race day anxiety, cognitive - behavioural therapy (CBT) is be useful. CBT ‘retrains’ your body’s reactions to a certain scenario i.e. so you won’t have anxiety on a race day. The other method you can trial is daily meditation, both ‘Calm’ and ‘Headspace’ are great apps.


Research has looked into the use of the FODMAP diet in controlling severe runners tummy. What is the FODMAP diet and can it be used by runners?

The low FODMAP diet is a diet which is low in fermentable carbohydrates. These carbohydrates travel to your large bowel (the bit rite at the end of your gut). Here, they are digested by good gut bacteria which results in gas production. They also draw in water. For some people, these carbohydrates result in digestive symptoms.

Traditionally the low FODMAP diet has only been used for people with chronic digestive problems e.g. IBS and inflammatory bowel disease, however there are now 2 studies looking at its use in athletes.

One study looked at 11 non-professional runners. The study compared a high FODMAP vs low FODMAP diet on digestive symptoms over the period of 6 days. The results suggested that a low FODMAP diet significantly reduced digestive symptoms Lis (2018)

The other study by Lis et al (2016) looked at just 1 athlete. This showed that a short-term low FODMAP diet could reduce digestive symptoms in a someone who was prone to symptoms.

The studies which having been carried out so far are very small and have been done poorly. This means that not only do we not know how safe the diet is long-term, but if it actually useful for runners tummy at all.

The low FODMAP diet is only designed as a short 4-6 week period which is then followed by a reintroduction period to pin-point triggers.

Long-term use of the diet is likely to reduce levels of good gut bacteria which could have negative consequences for other areas of the individuals health Staudacher et al (2017). Therefore, further research is needed before we start recommending this diet in order to help with runners tummy.


Can you just give some advice about if someone thinks they are intolerant to a food.

If someone is experiencing any digestive symptoms, they need to go to their GP to get ‘first line’ testing. This is when your GP will assess you, do blood tests and a stool test to rule out conditions such as infection, coeliac disease and bowel cancer.

If these all come back negative, then you will likely get a diagnosis of IBS. In order to determine if you have a food intolerance, there are a couple of options.

  1. For lactose and fructose intolerances you can do a hydrogen breath test. This may not may not be available on the NHS.

  2. For a lactose intolerance you can trial a period without lactose to see if it resolves your symptoms. Just be sure to use alternative calcium sources.

  3. You can see a dietitian. You may have multiple intolerances and so trying to figure this step out on your own is complicated. A dietitian will work with you to find out what your intolerances are and also how much of that food you can tolerate.

Please note - there are no blood tests for intolerances and you should only see a registered healthcare professional e.g. a dietitian or doctor.


What are your thoughts on probiotics use in runners?

The use of probiotics in runners could be beneficial in order to reduce the number of days affected by chest infections. There are two studies available which both suggest that taking a probiotic prophylactically can half the number of days that they are affected by a chest infection, Kekkonen et al (2007) & Cox et al (2010) .

The only thing that runners need to be aware of is that probiotics have a ‘strain specific’ affect. This means that one probiotic type has an entirely different affect than another.

The probiotics which were used for runners in the studies mentioned above are currently not available on the market. Therefore it would be a case of trialling a probiotic to see if it works for you and if you see no difference from your usual respiratory infection rate, to try a different product. The good news is, probiotics are safe to take regardless of whether you get a benefit or not.

Unfortunately, there is not yet any evidence to support the use of probiotics for runners tummy.


There is more information on runners tummy and how you can manage it here (Running to the loo).

If do suffer from bowel issues, one very important point to make is to not self diagnose. If you have a consistent problem or any change in bowel habit go and see your GP. or a registered dietitian.

For more information on Kirsten's clinic go to or you can take part in their free 30 day gut health challenge (click here for link)

Also follow Kirsten on Instagram @thehealthygutdietitian for regular tips and advice.



Lis D, Ahuja KD, StellingwerffT, Kitic CM, Fell J 2016 Case study: Utilising a low FODMAP diet to combat exercise induced gastrointestinal symptoms, Int J Sport Nutr Exerc Metab Oct; 26(5) 481-487

Lis D, Stelingwerf T Kitic CM, Fell J, Ahuja KD 2018 Low FODMAP: A preliminary strategy to reduce GI distress in athletes. Med Sci Sports Exercise an;50(1):116-123

Staudaucher HM, Lomer MCE Farquharson FM, Louis P, Fava F, Franciosi E, Scholz M, Tuohy KM, Lindsay JO, Irving PM, Whelan K 2017 A diet low in FODMAPS reduces symptoms in patients with irritable bowel syndrome and a probiotic restores bifidobacterium species: A randomixed controlled trial. Gastroenterology Oct: 153 (4): 936-947

Stuempflu KJ, Hoffman MD, 2015 Gastrointestinal distress is common during a 161 km Ultramarathon J Sports Science 33(17): 1814-21

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