Today I have a special post for you written by Chloe McLeod, who is an Accredited Practicing Dietitian and Director of The FODMAP Challenge. I’ve asked Chloe to share some tips about food chemical intolerance and how this can be the cause of IBS symptoms in some people.

Could food chemical intolerance be causing your IBS? | A Less Irritable Life


Have you been trialling the low FODMAP diet, but are finding that sometimes your symptoms don’t really seem to be all that better? Or some of them are better, but for some reason, some don’t seem to have changed at all? Or they’re better for a while… but then they seem to come back? Could it be that you have food chemical intolerance?


What is food chemical intolerance?

The foods we eat all contain natural food chemicals. Some of these are what’s known as ‘bioactive’ chemicals. These are naturally occurring (not due to pesticide use). In susceptible individuals, they can cause symptoms of IBS, such as bloating, wind, pain, constipation and diarrhoea… along with a whole host of other symptoms, such as migraines, skin rashes, itchy skin, mood changes, asthma and hayfever.

Similar to FODMAPs, food chemical intolerance comes down to a dose response; as long as your consumption of these chemicals stays below your threshold, symptoms stay under control. It is only when you consume more than you can tolerate that there is a problem.


The most common food chemicals

Salicylates and amines are the most commonly discussed naturally occurring food chemicals. Salicylates in particularly may be a triggers for IBS symptoms.

Natural food chemicals are commonly found in many plant foods, with salicylates richer in unripe, and amines richer in overripe produce. Foods which are particularly high in salicylates include herbs and spices, strawberries, capsicum and rockmelon. Foods high in amines include overripe banana, chocolate and canned seafood.

Many foods are rich in both, such as spinach, tomato, mushroom, broccoli, avocado, watermelon and many nuts and seeds.

Interestingly (or annoyingly, depending on how you see it), many high chemical foods are low FODMAP. Blueberries, raspberries, pineapple, cinnamon, turmeric, kale, spinach, tomato and capsicum are just some examples.

As you can see, many of us eat more and more of these healthy foods in a bid to feel better and be healthy! It is no surprise a common statement from clients is “but I eat so healthily, why do I feel so unwell?”

It’s important to remember that there are also synthetic chemicals which some individuals do not tolerate. Sulphites, nitrates and MSG are some of the most well-known versions of these. These man-made chemicals are most commonly found in dried fruit, processed meats and some Asian foods, respectively.


What’s the process?

Just like with determining FODMAP triggers, determining triggers of food chemical intolerance means an elimination phase, challenge phase and reintroduction phase. Elimination usually goes for 4-6 weeks, with challenges and reintroductions following. Yes, it is a long process, however this is currently the best way of determining what is causing symptoms.


Does this sound like you?

Worried this may be you? Take on the following steps:

  1. Keep a food and symptom diary, to help identify any patterns in food consumption and symptom development.
  2. Work with a health professional with skill in managing food chemical intolerance; determining triggers can be a bit like detective work, and getting expert help with this is likely to make the process much quicker and easier, particularly through the support they can provide through the process.


How to manage food chemical intolerance long term

We know just how frustrating it can be to determine, and manage food intolerances, however I think it is important to remember that knowledge is power. Once you know your triggers, your diet does not have to be as restrictive long term. This helps you make informed decisions when you do choose to have some of the higher chemical food choices.


Chloe McLeod is an Accredited Practicing Dietitian and Sports Dietitian. Her key areas of specialty are in IBS and food intolerance, along with sports nutrition and nutrition for arthritis and inflammatory joint disease. Chloe is director of the online program ‘The FODMAP Challenge’, which is an online program to assist individuals with determining triggers of IBS.

The FODMAP Challenge


Did you find this helpful? How about sharing it on social media to help other people who have IBS understand the role that food chemical intolerance can play in triggering symptoms.

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