Food Intolerance & Irritable Bowel Syndrome

IBS. These three little letters cause huge misery to thousands of people every day, with about 1 in 5 people in the UK suffering with it at some point in their life. Women in particular are more prone to IBS compared with men, especially in the age range of 30-39, where women are twice as likely as men to suffer with IBS. Characterised by abdominal pain, discomfort and changeable bowel habits, its effects are not just a nuisance, but something that can affect the quality of life and mental health of those who suffer its torment.

Unfortunately, there is little help available for those diagnosed with IBS and although anti-spasmodic medications can sometimes be prescribed by your GP, not everyone benefits from their use, or they may have only short term benefits without treating a potential underlying cause. So what can be done to help IBS symptoms and could the food you are eating be the cause of your symptoms?

Diet and IBS  

Many research studies suggest that IBS symptoms, in around 25% of patients, may be caused or exacerbated by one or more dietary components. As IBS affects the digestive system, it really makes sense to think that food and diet is going to influence symptoms in some way. Of course everyone is different, so certain foods that affect one person’s symptoms may not have the same effect for someone else, so it’s not a case of ‘one size fits all’. Certain foods can cause problems just because they are difficult to digest, whilst others cause problems due to their acidity or their ability to cause intestinal gas. One thing that is growing in awareness however, is the possibility of food intolerance and the impact that this can have on IBS symptoms.

Food Intolerance and IBS

It’s important to state here that there is a BIG difference between food intolerance and food allergy. They are different things and food intolerance is far more common than food allergy. An intolerance means that the body has difficulty in digesting and/or metabolising foods and thus can not only affect the digestive system, but can cause symptoms that involve many body systems such as the skin or sinuses. With one large research study showing more that 60% of IBS sufferers report worsening symptoms after a meal, with some (28%) reporting symptoms showing just 15 minutes after they had eaten and 93% reporting symptoms within 3 hours of eating, it is very likely there is a direct dietary and/or food intolerance link in many people that suffer with IBS.

So what foods can people commonly have an intolerance to?

Remember, one size does not fit all here!! Without having a test, or doing a food elimination diet, it is impossible to say exactly if, and what foods may be causing or aggravating YOUR symptoms. However, listed below are some of the most common food items that are known to be problematic in many, not all, people who suffer with IBS.

Wheat – Sensitivity to wheat and wheat products is seemingly on the increase with many people reporting they feel they are aggravated by its consumption. Wheat is eaten regularly in the UK, with many people eating some source of it in every meal of the day and using it as one of their main fibre sources.

Many people wrongly associate a wheat intolerance with coeliac disease, yet these are two different things. Coeliac disease is when a person has an adverse reaction to gluten (a protein found in grain products, including wheat), whereas a wheat intolerance (also called wheat sensitivity) is just a reaction to wheat and products containing wheat, commonly causing bloating, constipation and abdominal discomfort, which of course can all be symptoms of IBS. With an increase in the amount of people reporting that wheat affects them adversely, medics have now realised this is a new clinical entity and call it ‘non-coeliac wheat sensitivity’. If you feel wheat aggravates your symptoms, try reducing it or cutting it from your diet for 5-6 weeks. Make sure you are however replacing it with foods of a similar nutritional value that still provide you with a good source of carbohydrate.  Good replacements for wheat include rye, oats, rice, quinoa and corn based products. You can still bake all your favourite cake and biscuit recipes by replacing wheat based flour with rye or rice flour!

Milk and dairy products – Milk intolerance is something we hear more and more about, but the exact prevalence of it in the UK is largely unknown. We do know that many people with IBS self-diagnose themselves with a milk intolerance, reporting that their digestive symptoms worsen when consuming milk or milk products. This is often specifically related to the consumption of cow’s milk and cow’s dairy products, due to the difficulty in digesting these products, which can cause symptoms such as bloating, abdominal pain, excess flatulence and often looser stools or diarrhoea.


Many people who suffer with IBS symptoms can benefit from eliminating cows’ dairy products from their diet and replacing it with goats’ dairy. This is because the fat globules in goats’ milk are smaller than in cows’ milk so the human digestive enzymes (which breakdown food into smaller pieces), complete their breakdown much more rapidly. The proteins in goats’ milk also form a much softer curd in the stomach compared with cows’ milk, which again makes for easier digestion. Making this switch is easier than you think, with Delamere Dairy producing a whole range of goats’ dairy products that are available in supermarkets nationwide. If it makes you feel better and eases the load on your digestion, it is certainly worth a try!

Tomatoes – These are very acidic and are often something that can really irritate IBS symptoms and can also trigger acid reflux in some people too. It’s not surprising therefore that tomatoes can be quite a common food intolerance. Unfortunately these are not as easily replaced by alternatives, as there really isn’t an alternative to tomatoes. However, with a little careful planning you can certainly reduce or stop eating tomatoes and tomato based foods and use other foods instead. For example where you would usually use a tomato based sauce for pasta, use a pesto or cheese sauce or make your own vegetable based sauce using roasted vegetables and a liquidiser instead. Remember that baked beans are tomato based too, so if you are a lover of these and think tomatoes are causing or aggravating your symptoms then these will need to be eliminated as well!

Spices – These little powerful things, including chilli, curry powder, paprika, cumin etc. are not always the friendliest to people with IBS. It’s not necessarily because there is an intolerance to the spice, but because of the nature of spices they can act as an irritant to the gut wall. These are best avoided in the diet, especially if your IBS symptoms are particularly bad.

E-numbers – These can be found in an abundance of foods, especially processed ones. E-numbers can be things like colourings, preservatives, emulsifiers, sweeteners and flavour enhancers and many of these can be potentially problematic to people with IBS. Intolerance to certain E-numbers is fairly common and some studies have shown that the consumption of some additives can induce IBS symptoms. Some of the more common E-numbers that people can be intolerant to are: Monosodium Glutamate (E621), Aspartame (E951), Tartrazine (E102) and Sulphites (E220). The presence of these E-numbers in foods will be shown on the food label, so always remember to read the food labels on the foods and drink you consume.

IBS is not an easy thing to live with and although currently there is no known cure, you can certainly help manage your symptoms through a change in diet, elimination of foods, which you may be intolerant to and an increase in foods which naturally reduce inflammation and settle digestion such as ginger and peppermint tea. As I see in clinic with my clients, it is often lots of little changes done gradually, which will result in a big difference to symptoms!!

Note: If you are planning to do an elimination diet or cut out major food groups from your diet, you are advised to see your GP or a qualified nutritionist so this can be supervised, as consuming inadequate diets for prolonged period of times can have further detrimental effects on health.


  • The epidemiology of irritable bowel syndrome, 2014. Clinical Epidemiology

  • Irritable Bowel Syndrome, NHS, 2015

  • The role of diet in symptoms of irritable bowel syndrome in adults: a narrative review, 2009. Journal of American Dietetic Association

  • Non-Coeliac Wheat Sensitivity Diagnosed by Double-Blind Placebo-Controlled Challenge: Exploring a New Clinical Entity, 2012. The American Journal of Gastroenterology

  • Irritable bowel syndrome and hypersensitivity to food, 1985. Annals of Allergy, Asthma and Immunology

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