Are Prebiotics Good for IBS?

I’ve been chatting a lot about probiotics this month..the good, the bad and ultimately, whether they might be helpful for you. Last week, I gave you my opinion on whether they’re worth it or really just a waste of money. Well, I wouldn’t be doing you justice and fully covering the subject if I didn’t mention prebiotics. This is because, put bluntly, probiotics won’t work without prebiotics.

If you’re thinking ‘wait, wait, hold on a minute, I thought they were the same thing,’ don’t worry. You are most definitely not alone. I personally used to see the two words banded around and wonder what the hell they were. Did they just mean the same thing or was there a difference?

First we’ll clear the air and talk about exactly what prebiotics are, why they’re different from probiotics and why they’re so important. Then, we’ll talk about what really matters to you..are they good for IBS and should you be eating them.


Prebiotics are defined as foods that feed or stimulate the probiotic (good) bacteria in your gut in a way that improves your health.

There’s all this chat about probiotics but, the funny thing is, probiotics can’t survive without prebiotics. I’m going to go back to the garden analogy to help bring this to life. If your gut is the garden, then the good bacteria (probiotics) are the plants in that garden. Well, your plants aren’t just going to grow by themselves are they? They need food..and that’s where prebiotics come in. Prebiotics are like the plant food, or fertilizer that makes your plants grow and thrive. Without them, you’d have planted a whole bunch of pretty plants (i.e. spent money on expensive probiotics) but you wouldn’t be feeding them, so you’d be left with a garden full of dead plants within a few weeks.

What I’m trying to say is, probiotics will be a waste of money unless you feed them with prebiotics.


They’re actually not as complicated as they sound. All fruit and veg is prebiotic because it contains soluble fibre. Soluble fibre is the type that absorbs water and forms a gel like substance. It survives stomach acid and isn’t absorbed further up, so is broken down and fermented by the bacteria in the colon. This is what makes it a prebiotic. FYI - wheat is mainly insoluble fibre, so isn’t a prebiotic. So, it’s not just about fibre but the right type of fibre.


You now know that probiotics need prebiotics to work but, if you’re not planning on taking probiotics, then why do you need to worry about prebiotics?

Well, they’ve got a whole host of other benefits, including:

  • Increasing the amount of calcium and magnesium you can absorb (which you need for healthy bones and muscle function)

  • Boosting your immune system

  • Lowering your cholesterol

  • Improving insulin sensitivity

  • Supporting weight loss

  • Helping with a leaky gut (and if you’ve got IBS, you’ve most likely got one)

Even if you’re not interested in probiotics, reducing the numbers of bad bacteria in your gut and warding off any that get down there is only going to do you favors, and prebiotics help you do just that. They do this by feeding your good gut bacteria, which produces lactic acid. That lactic acid then lowers the pH of your gut, which wards off bad bacteria, as they grow in high pH environments. Then, when those good bacteria grow, because they’re feeding them, they produce antibacterial molecules, which further wards off any nasty bacteria. Double whammy.


 As I mentioned, all fruit and veg are prebiotics, because they all contain soluble fibre. So, it doesn’t have to be complicated. You can ‘take’ prebiotics by simply eating more fruit and veg (which what we all know we should be doing anyway, right?!).

However, some foods that are especially high in prebiotics are those that contain inulin, like the below:

  • Jerusalem artichoke

  • Raw leeks and garlic

  • Chicory root

  • Asparagus

  • Raw onions

  • Raw dandelion greens

  • Kiwi fruit

If you’re wondering how much of these foods you should be eating, the recommended amount is 2-6 grams per day. However, that’s a massive faff to have to measure out and it will be different for everyone, so, I know it sounds boring, but I’d recommend just trying to have 5 servings of fruit and veg a day. If you can have more, great, but that can already be a stretch for some.

Now, as you read that list you might have been thinking ‘but these are all high FODMAP’ or ‘these are all foods that make me bloated.’ That’s where it gets a little less simple and a bit more complicated.


You’re right. A lot of foods that are especially high in prebiotics are also especially high in FODMAPs and therefore likely to make you bloated or cause other symptoms. That’s no coincidence, and there is a LOT of overlap between prebiotics and FODMAPs. Prebiotics, as we said, are foods (fibre) that are fermentable by bacteria in the colon. FODMAP stands for stands for Fermentable, Oligo, Di, Mono-saccharides And Polyols. Find out more about the low FODMAP diet here.

Notice the word ‘fermentable’ in both of those definitions?! It’s the fermentation of these foods by your gut bacteria that leads to gas. In ‘normal’ people that doesn’t cause any problems. However, in people with IBS, they can trigger symptoms because the nerves that line our intestines are overactive. So, normal things like this gas production causes the intestines contents to expand and the wall to stretch. This triggers pain and bloating for us with IBS, as well as changes in gut movements and bowel habits, constipation, diarrhoea or a mix. So, the main premise of the the low FODMAP diet for IBS is limiting fermentable foods.

So, if you have IBS and you start eating lots of prebiotic foods, you’re likely to get gas, bloating and lots of digestive problems, because of the FODMAPs. This makes it very confusing and may leave you wondering whether you should be eating prebiotics at all…


To answer that question, I’ll go back to the garden analogy. Just like I said probiotics need prebiotics, prebiotics need probiotics. Your plants need food and fertilizer, but your fertilizer also needs plants to feed. If there’s no plants for it to feed, it’s just going to start feeding all your weeds, and you’ll end up with a garden full of healthy weeds. So, in order to benefit from the positive effects of prebiotics, you need to have enough good bacteria in your gut for them to feed.

This is why they may not be helpful for you if you have IBS, at least not at first. When you have IBS, meaning you’ll benefit from the low FODMAP diet, your gut isn’t as strong and it doesn’t have enough good bacteria to feed yet. This means it’s not strong enough yet for prebiotics, so you’ll experience all of those nasty symptoms.


So, if you’ve got IBS, I’d still give you the same advice around prebiotics - try to have 5 servings of fruit and veg a day. However, I’d recommend sticking to low FODMAP fruit and veg at first, such as kiwis, spinach, kale etc etc (there are so many!) as well as low FODMAP portions (find out more about this here) of other veg. This will enable you to get the benefits of prebiotics and slowly build up your good bacteria, whilst avoiding symptoms at the same time…the perfect balance.

Over time, if you stick with low FODMAP prebiotics, you’ll strengthen your gut and build up your good bacteria. This will take time, but it will happen, and once you’ve strengthened your gut, you’ll be able to gradually start adding in some higher FODMAP prebiotics.


  • Probiotics won’t work without prebiotics.

  • Aside from helping probiotics to work, they also ward off bad bacteria and have a whole host of other benefits.

  • Prebiotics are defined as foods that feed or stimulate the probiotic (good) bacteria in your gut in a way that improves your health.

  • All fruit and veg is prebiotic because it contains soluble fibre.

  • To get ‘enough’ prebiotics, aim for 5 servings or fruit and veg a day.

  • There is a LOT of overlap between prebiotics and FODMAPs due to their fermentable nature.

  • If you have IBS, prebiotics may cause symptoms for you as your gut isn’t yet strong enough and doesn’t have enough good bacteria yet.

  • So, if you have IBS, I recommend 5 servings a day of low FODMAP fruit and veg, so you can strengthen your gut whilst keeping symptoms at bay.

FODMAPs are one major trigger for IBS symptoms. However, there are lots of others! Download the IBS Triggers Checklist to find out what 20 things that could be triggering YOUR IBS. Download it here - it’s FREE.

What did you think prebiotics were? Has this cleared up any confusion for you? Let me know in the comments below.

Thank you so much for taking the time to read this and letting me be a part of your journey in taking control of your gut, eating well and living your life.

Sophie x




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