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Have you tried adjusting fibre and fluid in your diet and then trialling the Low FODMAP diet but still haven’t achieved adequate relief?

If so, you are probably not the only one! There are some foods that can trigger IBS symptoms that fall outside of these common IBS trigger foods.

Here is a list of some of them:

High fat foods

Many people with IBS are sensitive to dietary fat intake and find that it can worsen their IBS symptoms. Fat sensitivity may contribute to symptoms such as cramps, increased gas, bloating and diarrhoea. One of possible reasons is that fat can impact gut motor activity and slow down digestion.


Caffeine may play a role in triggering IBS symptoms, mainly diarrhoea. This might be explained by the ability of caffeine to increase gut motility, which means it can increase the movement and transit of foods within the digestive system.


Alcohol can be a gut irritant which may affect gut motility, permeability, and absorption. Many alcoholic drinks also contain FODMAP sugars, which can further trigger IBS symptoms in some people.

Spicy foods

Some people find that their symptoms worsen after eating spicy foods. This can be explained by the presence of Capsaicin in chillies, which is a natural food chemical that can irritate the gut in some people with IBS.


A low fibre diet can trigger IBS symptoms due to its ability to increase stool weight, decrease colon transit time (the time it takes for food to travel through the colon), and serve as a food source for microbes in the colon. That said, a high fibre diet might not be tolerated by some people. So, it is recommended to increase fibre intake gradually and have adequate water intake.

Getting on top of your IBS Symptoms

A Low FODMAP diet is still the best evidenced approach for the dietary treatment of IBS. However, some people with IBS find symptom improvements after reducing their intake of the above foods. Altering the amount and type of fibre you eat may also help.

Amount of fibre

Increasing fibre intake slowly and gradually is recommended to avoid gut discomfort. The goal is to reach about 25-30g of fibre per day. It is also important to drink plenty of water (aim for 30ml per kilogram of weight per day e.g. 30ml x 70kg = 2.1L per day)

Type of fibre

Different types of fibre play different roles in the intestines. For example, insoluble fibre such as wheat bran help feed the bacteria in the large intestine. This may trigger bloating in some people but can be improved by having small amounts less frequently. Soluble fibre such as psyllium, linseeds and oats help bulk up the stool, which may be helpful in constipation and diarrhoea.

Some studies have found that partially hydrolysed guar gum (PHGG) can soften and increase the stool weight. So, PHGG may be beneficial for managing IBS-C (Constipation) and IBS-D (Diarrhoea). PHGG might also promote the growth of beneficial bacteria due to its prebiotic properties.

If you need help to modify your diet to improve your symptoms, get in touch with our experienced dietitians.


DOI: 10.1023/a:1016419906546


Co-written by Intern Claudia Khalil @easy_nutrition_solutions and Nicole Dynan