10 foods to avoid to help prevent IBS– explained by top nutritionists

woman holds her hands to her stomach as she sits on cream sofa
Foods to avoid if you have IBS Jacob Wackerhausen

IBS can be a drag. Anyone who suffers from the condition will understand how difficult it can be, from endless cramps to bloating to the size of a woman in her second trimester after almost every darn meal.

To try and help make things a little easier for those affected by IBS (irritable bowel syndrome), we spoke to nutritionist Fiona Hunter and Kirsten Jackson, The IBS Dietitian for their tips on which types of food and drink to consider avoiding.

To note, we've heard before that cutting certain foods out of your diet won't necessarily help to stop IBS. "It’s important to understand that IBS can cause different symptoms for different people," says Hunter. "Sufferers can react to different foods so there is no one-size-fits-all diet when it comes to IBS."

Jackson echoes this point, saying that even if someone does have a specific food intolerance, they will have a tolerance level. "It is important to figure that out so that their diet can remain as varied as possible," she says. "For example, someone may tolerate one slice of bread, but two slices may cause them symptoms."

Basically, it's generally not advised to cut out any whole food group from your diet (the Eatwell Guide says a healthy diet includes fruit and vegetables, potatoes, bread, rice, pasta and other starchy carbohydrates, beans, pulses, fish, eggs, meat and other proteins, dairy and alternatives, and oils and spreads). But if you have a medical reason to, in this instance because of IBS (and it's been approved by your doctor), it could be worth a try.

woman in pain
Peter Dazeley

If you've got a sensitive gut, the chances are you'll react to most foods, but Hunter suggests that keeping a food diary is the best way to work out by process of elimination which ones might flare up your IBS more than others. "Not everyone will react to every food on the list below," she notes, advising people not to cut out everything, because that "could leave you eating a very restrictive diet".

So, here are some of the worst offending foods (and drinks) to look out for when it comes to IBS flaring.

What are the worst foods for IBS?

1. Onions

Onions have been singled out because of how gassy they are, but they aren't the only veg that's guilty of that – cauliflower and Brussels sprouts are, too. Hunter says the issues arise because some IBS sufferers have difficulty fully digesting these foods, meaning, "They pass into the large bowel where they are digested by the bacteria that we all have living in the bowel.

"A by-product of this digestion is gas, which can cause bloating and pain."

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2. Spicy foods

This one's probably kind of obvious. It's well known that chilli can irritate the lining of the gut, but it also "speeds up gut transit time, increasing the risk of diarrhoea and pain," says Hunter.

3. Fizzy Drinks

Fizzy drinks = gas. Gas = an increased risk of bloating. That's just how it is, unfortunately.

overhead view of glass of cola being poured

4. High-fibre foods

This one is particularly dependent on the person. High-fibre foods are notorious for getting your bowels moving, which is good in most instances, but not always if you've got IBS. "Lentils, baked beans, wholemeal bread and wholegrain cereals are all examples of high-fibre foods," says Hunter. "For some IBS sufferers, a high-fibre diet can help ease symptoms like constipation, but for others, high-fibre foods can be a trigger because they can irritate the gut lining and can be difficult to digest." For this reason, Hunter advises introducing more fibrous foods into your diet gradually if you're currently eating a relatively low-fibre diet – it'll give your body time to adapt.

It’s worth noting that beans and pulses are high in FODMAPs, which are a collection of short-chain carbohydrates that can trigger symptoms in people with IBS. "This is portion dependant so it may be worth someone with IBS trialling smaller portions to see if they can be tolerated," says Jackson.

5. Sugar-free sweets and gum

It might feel harmless, chewing a bit of sugar-free gum, but this can be one of the worst culprits for causing someone to bloat and experience IBS symptoms. This is because sugar-free sweets and gum "often contain sorbitol or other sugar substitutes which people with IBS find hard to digest", explains Hunter.

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6. Alcohol

"Alcoholic drinks can worsen IBS symptoms by causing loose stools and also indirectly by worsening mood and sleep," says Jackson. "People with IBS should avoid or reduce their intake where possible." Hunter advises IBS sufferers to limit their intake to no more than two units a day, as well as ensuring they have at least two alcohol-free days a week.

7. Fatty foods

They might be tasty, but high-fat meals (think cheesy goodness, basically) can trigger loose bowel motions due to something known as the gastro-colic reflex. "This is a reflex in the gut which 'moves things along' when the stomach is being filled," says Jackson. "This reflex is in everyone but in those with IBS, their reflex is more sensitive so they may want to reduce their portions of high-fat foods."

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8. Caffeine

You might rely on your daily coffee like it's oxygen, but caffeine can be a no-no for some IBS sufferers. The reason? "Caffeine is a stimulant found in coffee, sports drinks, energy drinks and even chocolate," says Jackson. "In some people with IBS, this can worsen pain and loose stools, but not in everyone with IBS. Caffeine can also worsen anxiety and poor sleep symptoms which are directly linked to IBS symptoms." If you have IBS and consume caffeine regularly and you’re experiencing anxiety, loose stools, poor sleep or pain, Jackson’s advice is to reduce your intake to see if it improves symptoms. Make sure to reduce your caffeine intake gradually, though. Going cold turkey might bring on withdrawal symptoms.

9. Lactose and dairy products

Some milk and dairy products contain a type of sugar called lactose, which needs to be broken down by the enzyme lactase before it can be absorbed. But when a person's gut lining is damaged, it's common to lose the ability to produce lactase which means that the body can’t digest or absorb lactose. This means it passes into the large bowel – much like what happens with vegetables like onions and cauliflower, where the bacteria digesting it produces gas. "If someone is lactose intolerant, this is not the same as a milk allergy and they will be able to tolerate a certain amount before getting symptoms," says Jackson. She also stresses that if you’re avoiding lactose, you’ll need to ensure you get your calcium from fortified alternatives.

close up of pouring oat milk into black coffee cup making coffee at home

10. Foods containing FODMAPs

As mentioned FODMAPs are a collection of short-chain carbohydrates (sugars) that aren't absorbed properly in the gut. If you want the more scientific definition, they're "foods which contain fermentable oligosaccharides, disaccharides, monosaccharides and polyols". Some examples include garlic, bananas, wheat and apples, says Hunter (which of course aren't generally bad foods). You can read more about a low FODMAP diet on the NHS here.

Remember, just because a particular food or food group might cause your IBS to flare up, doesn't mean you have an allergy to it – that's a different thing entirely. But eliminating or reducing certain foods your gut is sensitive to could be one way to reduce the effects of IBS in your everyday life.

And on that note, Hunter has a couple of other pearls of wisdom for how best to manage your IBS:

  • Eat regularly: "Have three small meals with a couple of healthy snacks between. Skipping meals and leaving long gaps between meals can affect gut mobility, making it sluggish and increasing the risk of constipation. One study found that subjects with irregular eating habits were 3.2 times more likely to suffer from IBS than those with regular eating habits."

  • Avoid large/heavy meals: "This can overload the gut, increasing the risk of bloating and diarrhoea. IBS is between two-four times more common in binge eaters."

And remember, everyone is different and all foods affect us differently. So just because a type of food has been mentioned above, doesn't necessarily mean you need to rush to slash it from your diet. Take the time to figure it out properly first!

This article is not intended to be a substitute for professional medical advice or diagnosis. Always seek the advice of your physician or other qualified health provider with any questions you may have regarding a medical condition.

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