Did you know that there are a range of non-FODMAP foods that can trigger IBS?  Keep reading to find out the foods that could be triggering your IBS symptoms!

1. Alcohol

Drinking larger quantities of alcohol can cause alcohol-induced intestinal inflammation, by altering the microbiota and damaging the mucosal layer of the intestine. This inflammation can reduce the absorption of nutrients and trigger a range of IBS symptoms.

Alcohol can also trigger diarrhoea! Alcohol increases the intestinal motility, which is the speed that food moves through your gut. During digestion, contractions occur in the large intestine (colon) to move the stools along while absorbing water to form the faeces, which is eventually excreted. Alcohol causes these contractions to occur at an increased rate. This means that there is less time for water to be absorbed in the colon, resulting in the faeces having a diarrhoea consistency. Diarrhoea can contribute to dehydration, due to excess water being excreted.

Alcohol is also a diuretic, which means that it causes the body to produce more urine, so more water is lost from the body. Drinking alcohol without other fluids can make you dehydrated. On top of this, dehydration can further contribute to constipation as there is less water available to soften the stool.

So as we can see, excessive alcohol consumption can be a trigger for both IBS-D (diarrhoea predominant) and IBS-C (constipation predominant).

If you do decide to have an alcoholic drink, the National Health and Medical Research Council recommends to have no more than 2 standard drinks per day, and to have 2 alcohol-free days each week. However, even this amount of alcohol may still trigger symptoms in some people. Your dietitian can provide advice on the amount of alcohol you can consume, and to help determine if certain types of alcohol are causing your symptoms.

2. Caffeine

Caffeine can also speed up your gut motility, similarly to alcohol. This can prevent the stool from forming properly in the colon and can cause diarrhoea. However, not everyone with IBS is affected by caffeine. All coffee products contain caffeine, with barista made coffee containing more caffeine compared to instant or ground coffee. Decaffeinated coffee and tea are great alternatives to coffee if you are sensitive to caffeine. The NICE IBS guidelines suggest limiting your coffee intake to 3 cups per day. Make sure to talk to your dietitian about how much caffeine you can consume.

3. Spicy Foods

Spicy foods with ingredients such as chilli peppers can be a particular issue if you have IBS as the nerve endings in your gut are more sensitive. Chilli peppers contain a component called capsaicin. This can cause heat or burning sensations and trigger the nerve endings to send signals of pain to the brain, meaning that spicy food can trigger abdominal pain. Many spice blends and pastes contain onion & garlic which are high FODMAP foods that can also contribute towards IBS symptoms. However, there are a range of spices that are low FODMAP such as black pepper, paprika, cumin, turmeric, and thyme, just click here to see the full list.

4. Fat

High fat foods can also trigger IBS symptoms in some people. High fat foods can trigger your gastro-colic reflex, which is a reflex that naturally occurs when you eat food. The reflex causes contractions in your body to move food through the digestive system and make room for the food that you just ate. This is a normal reaction with eating. However, people with IBS may find that high fat foods trigger their gastro-colic reflex to contract at an unusually fast rate. This can cause symptoms such as abdominal pain, flatulence and the urge for a sudden bowel movement. Foods such as burgers, pizza and other fried foods high in fat can be triggers, and may need to be limited. However, that doesn’t mean you can’t still enjoy your favourite foods! Homemade versions are a great alternative as they usually contain less fat than the takeaway options.

5. Carbonated beverages

Carbonated beverages such as soft drinks contain excess carbon dioxide gas. This gas enters your digestive system and can trigger bloating and pain from a build-up of excess gas inside the gut. Many carbonated drinks also contain high fructose corn syrup or sugar alcohols (polyols), which are high FODMAP ingredients that can trigger IBS symptoms. Carbonated drinks like cola and energy drinks also contain caffeine, which can also affect some people with IBS.

If you choose to include carbonated drinks, look out for high FODMAP ingredients and limit your serve size if you continue to experience symptoms. Non-carbonated drinks may be useful for easing symptoms such as flavoured cordials or iced tea.

6. Fibre

There are 2 types of fibre: insoluble and soluble. Insoluble fibre helps to make up the bulk of your stool because it does not dissolve in the digestive system. It enables the stool to form and makes the stool pass through your bowels quicker, so can help prevent constipation. Nuts, grains, beans, legumes, and fruit and vegetable skins are all good sources of insoluble fibre.

However, some people with IBS may find their symptoms such as diarrhoea can worsen with increased consumption of insoluble fibre. In this case, it may be better to focus on eating more foods that are high in soluble fibre.

Soluble fibre dissolves in water and forms a gel in your digestive system. This slows the process of digestion, which can help if diarrhoea is an issue. Soluble fibre is found in barley, fruit, vegetables, oats, nuts and beans.

Many foods contain both soluble and insoluble fibre, such as fruit and vegetables with insoluble fibre in the skin and soluble fibre in the flesh. Both types of fibre are important as part of a balanced diet. It is also important to increase fluid intake when adding more fibre to your diet.

Fibre can also be found in the form of supplements. If taking a fibre supplement, check the ingredients as many contain high FODMAP ingredients. Your dietitian can recommend specific foods to help manage your constipation or diarrhoea.

7. Water

Water is a good beverage for anyone with IBS because it does not trigger the unwanted symptoms from other beverages such as alcohol and carbonated drinks. Drinking adequate water can also assist with softening stools to help prevent constipation. The NICE IBS guidelines recommend drinking 8 glasses of water each day.  

8. Meal Size

The size of your meals can also affect IBS symptoms. Consuming larger meals can sometimes contribute to bloating, distention, abdominal pain and diarrhoea by triggering the gastro-colic reflex as mentioned above. Instead of just having 3 large meals, try consuming 3 smaller meals plus snacks throughout the day as this is less likely to speed up the contractions from the gastro-colic reflex.

All of these foods will affect people differently, so it is important to seek guidance from your dietitian about specific triggers for your IBS, and to receive guidance about what foods you may need to avoid.

Written by: Emily Monro (student dietitian)

Edited by: Rebecca Ponsford (APD)


  1. Bishehsari et al. : https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5513683/
  2. Dr Jane Varney: https://www.monashfodmap.com/blog/does-caffeine-affect-ibs-symptoms/
  3. Esmaillzadeh et al. : https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3801318/
  4. McKenzie et al. : https://www.ncbi.nlm.nih.gov/pubmed/27272325
  5. NHMRC: https://www.nhmrc.gov.au/health-advice/alcohol
  6. National Institute for Health and Care Excellence: https://www.nice.org.uk/guidance/cg61/chapter/1-Recommendations


8 IBS Food Triggers That Aren’t FODMAPs
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