Prebiotics and IBS – what's the story?

In this lesson we'll look at prebiotics and their impact on IBS

By Laura Tilt

What are prebiotics?  

Prebiotics aren't living bacteria; they're food for the beneficial bacteria already living in your gut.

They can help your beneficial bacteria grow and increase the helpful compounds they make. These compounds play a role in keeping the lining of your gut healthy.  

Why might they be useful in IBS?  

Some research shows the numbers of beneficial bacteria are reduced in people with IBS compared to healthy controls.

Lower levels of some beneficial bacteria have also been linked with increased symptoms. We also know that restrictive diets can alter the microbiome too.  

The theory is that prebiotic fibres may help to encourage a healthy balance of gut bacteria.  

Prebiotics in food  

Most prebiotics are types of fibre. Many plant foods contain prebiotic fibres including: asparagus, onion, garlic, beans, artichokes, wheat, bananas, leeks, and chicory root.  

You’ll notice that most of these foods are also rich in FODMAPs. This means these foods can trigger gas, wind, and bloating in people with IBS.  

So, while prebiotics can be beneficial, it's important to pay attention to how much you’re consuming. This will help avoid worsening symptoms.  

Prebiotics as supplements  

Prebiotics are also available in supplement form. There are two main forms:  

  • inulin-type prebiotics: usually made from chicory root fibre, you may see the words ‘inulin’ or ‘fructo-oligosaccharide’ on the label.
  • Non-inulin type prebiotics like β-GOS (produced from lactose using enzymes), pectin and guar gum 

What’s the evidence for their use in IBS?  

Most studies into prebiotics have used supplements in people without gut conditions.  

The few studies in people with IBS have shown that prebiotic supplements can increase beneficial bacteria. However, they can also increase symptoms, depending on the type.  

Inulin type prebiotics are easily broken down by gut microbes and increase gas and bloating. Non-inulin type prebiotics tend to result in less gas production and may better tolerated in people with IBS.  

Using Prebiotics if you IBS: 

Based on current research, here's what you need to know: 

  • Incorporating some prebiotics into your diet is beneficial but go with small portion sizes to begin with  
  • Almonds, hazelnuts and pistachios and some seeds like chia are a source of prebiotics. Try including a low FODMAP serving of nuts or seeds daily.  
  • Rolled oats are a prebiotic fibre – try them in overnight oats, porridge or whizzed into a smoothie 
  • Canned pulses, drained and rinsed, offer prebiotic fibre with less FODMAP content. As part of a low FODMAP meal, most people can tolerate a low FODMAP serving.
  • During the reintroduction phase, determine which prebiotic foods you can tolerate and in what portion size. Then, include these foods when you start the long-term personalisation.
  • If you want to try a supplement, go for a non-inulin type (for example, Bimuno, which is available in the UK).  
  • If you do choose an inulin type, go for a lower dose (less than 6 grams/day)