Are the Fructans in Wheat Triggering Your IBS Symptoms?

Do your symptoms flare up after you eat bread, pasta, onions or garlic? Mine do. I used to get really bloated after a delicious meal of pasta with a rich tomato sauce with onion and garlic and I never knew why until I learned about fructans.

What are fructans?

Fructans are a type of carbohydrate, an oligosaccharide which is a chain of fructose molecules with a glucose molecule at one end. They can also be can be known as fructo-oligosaccharides (Oligos-FOS) or inulin. In order to absorb the molecules, our body needs to break down the chain into single molecules. This is where the problem lies because humans don’t have the enzymes needed to break the chain so it travels through the small intestine to the colon where it's fermented. This process produces gas. For people who don’t have IBS this may not be a big problem as the colon will relax and accommodate the gas, but for those of us with a sensitive digestive system, it can cause big issues!1,2

What foods contain fructans?

If you do have an intolerance to fructans you may not have to avoid all fructan containing foods because that could be quite limiting and you many miss out on lots of nutrients and yumminess!

They are found in lots of different types of fruits and vegetables, grains, nuts, legumes and some types of tea. Some serving sizes are higher than others and some parts of the plants are high in fructans and some parts are not. Here are a few of the common foods that contain fructans:


  • Dates
  • Dried figs
  • Prunes
  • Plums
  • Grapefruit
  • Watermelon


  • Garlic
  • Leek
  • Onion
  • Scallion/spring onion/green onion)
  • Artichokes - globe and Jerusalem


  • Wheat
  • Rye
  • Barley


  • Cashews
  • Pistachios


  • Black beans
  • Kidney beans
  • Split peas


  • Chamomile
  • Fennel
  • Carob

Which foods are higher in fructans?

The tricky thing about fructans is that some of the foods with fructans may cause issues and some may not. This may be because some foods are higher in fructans than others or it can just be an individual tolerance issue. It could also be due to the processing of the food.

Two prunes are low in fructans but eating four at a time makes them high in fructans. Whereas just ½ a clove of garlic has a high amount of fructans. It may also depend on which part of the plant is being consumed because the green leaves of the leek are fine to eat but not the bulb, this is the same with a scallion. I have trouble eating raw cashews but if they have been fermented and made into cashew cheese then I have no issues at all.

The Monash University Low FODMAP Diet app is quite helpful in figuring out what foods contain fructans and what quantities of fructan containing foods are considered low or high in fructans.3

Do gluten-free products contain fructans?

The protein gluten can be found in grains that also contain fructans including wheat, rye and barley. So you may think that avoiding gluten-free products will mean that you can avoid triggering your symptoms, but that’s not always the case!

You may think that buying a gluten-free pizza means you’ll be safe, but not if it also includes garlic and onion in the tomato sauce. Or perhaps a gluten-free dessert, but not if it contains dates. It can be a minefield out there! I learned the hard way after eating some delicious gluten-free sausages recently only to find out later when my symptoms hit that they contained garlic and onion powder!

How can I tell if fructans are a trigger for me?

Fructans are in so many different types of foods and it can be really difficult to figure out what you can eat and what you can’t, particularly if you have other triggers like fructose or lactose.

One way could be the low FODMAP diet which eliminates all high fructan containing foods for the elimination period and then gradually reintroduces them again to help figure out your tolerance level. Another option could be a symptom diary where you can write down what you ate and how you felt to help pinpoint those trigger foods. You could also make an appointment with a health professional that specializes in the low FODMAP diet or food intolerances and have them to help you through the process.

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This article represents the opinions, thoughts, and experiences of the author; none of this content has been paid for by any advertiser. The team does not recommend or endorse any products or treatments discussed herein. Learn more about how we maintain editorial integrity here.

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