Nutrition and the Irritable Bowel

by Amanda Whitford, MSc, BSc, NZ Registered Dietitian


These days I would not be surprised if everyone knows at least a handful of people who suffer from irritable bowel syndrome (IBS). While it may not be a common topic of conversation for many, talking about bowel movements and symptoms is just a typical part of my day as a Dietitian – and I love it! …Why? Because it can have such a significant effect on a person’s quality of life, and it should not be ignored or undermined.

Irritable bowel syndrome refers to a functional bowel disorder, ie. there is no physically detectable problem. The symptoms range from person to person and may include changes in bowel habits such as diarrhoea and/or constipation, bloating, gas, nausea, pain, cramping. Having these symptoms does not necessarily mean you have IBS, and there are specific criteria, including types and timelines of symptoms, that need to be met for diagnosis- getting a medical diagnosis is essential!!!

This is because there are so many bowel conditions that have similar symptoms, so it is important to your health and well-being to ensure that it is not something that needs more urgent medical attention. Before you look to a nutritionist or dietitian for help with your symptoms, see your GP and/or a gastroenterologist. 

So what triggers IBS?
While this is still a hot topic of debate, it is very variable from person to person. There is a MASSIVE lifestyle component, and stress has got to be the number 1 contributing factor that I see in clinics. Other factors like sleep, fluids, fibre, caffeine, exercise, gut bacteria, eating environment can also play a role… and then of course there is diet.

While there are many common dietary triggers of IBS, there has been a new movement in IBS treatment called the low FODMAP diet and this is thought to be effective in treating somewhere between 70-80% of IBS sufferers. FODMAPs are short chain carbohydrates that are poorly broken down & absorbed in the small intestine. They have an osmotic effect, meaning they draw water into the intestine, creating loose bowel movements. They then move into the large intestine where they are fermented by the gut bacteria producing gas and causing bloating.

How do you know if a low FODMAPs diet is for you?
In my practise, I believe it is important to address any relevant diet & lifestyle factors before commencing a FODMAPs diet. If these are not identified and eliminated first, it will be impossible to get an accurate indication of whether there are true FODMAPs intolerances. FODMAPs is a very restrictive diet, and it is not a long-term solution.. the re-introduction phase is crucial! This is because it eliminates a huge amount of fibre from the diet – the main food for our gut bacteria. Long term FODMAPs has been shown to reduce the diversity of our gut bacteria – this is not a good thing considering lack of diversity has been linked to a growing number of health conditions.

Another thing I see in clinic a lot is where people have taken the good old kiwi ‘do it yourself’ approach to a FODMAPs diet…  followed by a conviction that it doesn’t work. Usually after further probing, I find out they’ve been doing a loose FODMAPs exclusion, also known as only excluding the FODMAP foods that they want to… sorry to disappoint but this is essentially a waste of time! Unless you are sure that you tolerate certain types of FODMAP (there are several), it is best to avoid them all as the main point of exclusion is to remove all potential irritants and let the gut rest before reintroductions. This process should be done under supervision of a trained professional to optimise nutrition intake, ensure adherence, and to apply an appropriate reintroduction protocol.

Take home messages:

  1. IBS is a complicated functional disorder, with differing symptoms and triggers from person to person.
  2. Medical diagnosis is important to eliminate other bowel pathologies with similar symptoms.
  3. Treatment should have a holistic focus with consideration of all potential diet and lifestyle factors that can influence gastrointestinal function.

Amanda Whitford

Amanda is our Registered Dietitian at the Remuera branch of Results Nutrition Centre. She has a passion for all things health and wellness and a special interest in the nutritional management of gastrointestinal conditions.

Struggling to control your IBS symptoms? Book in to see Amanda and she’ll work with you to conduct a thorough investigation of what your dietary and lifestyle triggers might be, followed by an appropriate action plan tailored to you.