Best Foods for IBS and Bloating: What the Research Actually Says

By Bella Dorey, BANT Registered Nutritional Therapist

If you've been told you have IBS and handed a low-FODMAP diet sheet, you're not alone. It's one of the most commonly given pieces of dietary advice for digestive symptoms - and while it can be genuinely useful short-term, it's rarely the whole answer.

The reality of IBS and chronic bloating is that they're rarely caused by one single thing. Which means the most effective dietary approach isn't one-size-fits-all either.

Here's what the research actually supports for foods for IBS- and what's often missing from the standard advice.

First: what's actually causing your bloating?

Bloating, cramping, constipation, loose stools and unpredictable digestion can have multiple overlapping drivers, including:

• Gut microbiome imbalances (dysbiosis) — an overgrowth of gas-producing bacteria or a lack of beneficial species

• Intestinal permeability — a compromised gut lining that triggers immune responses to foods that would normally be well tolerated

• Visceral hypersensitivity — heightened nerve sensitivity in the gut, often linked to chronic stress

• Small intestinal bacterial overgrowth (SIBO) — bacteria that have migrated into the small intestine where they ferment food and produce excess gas

• Bile acid issues — relevant if loose stools are your primary symptom

• Food intolerances — genuine reactions to specific foods, though these are often secondary to gut permeability rather than primary causes

Understanding which of these is most relevant to you matters enormously, because the dietary approach for SIBO is different to the approach for dysbiosis, which is different again from visceral hypersensitivity.

What the evidence supports for foods for IBS

Increasing fibre — carefully and gradually Soluble fibre from foods like oats, lentils, apples, carrots and flaxseeds feeds beneficial gut bacteria and supports stool consistency. However, rapidly increasing fibre when the gut is already inflamed or dysbiotic can initially worsen symptoms. Gradual introduction alongside adequate hydration is key.

Fermented foods Multiple randomised controlled trials have demonstrated that regular consumption of fermented foods — live yoghurt, kefir, sauerkraut, kimchi, miso — significantly increases gut microbiome diversity and reduces inflammatory markers. A 2021 Stanford study found fermented foods outperformed a high-fibre diet for improving microbiome diversity in just ten weeks.

Polyphenol-rich foods Polyphenols — found in colourful vegetables, berries, green tea, dark chocolate and extra virgin olive oil — act as prebiotics, selectively feeding beneficial bacteria. They also have anti-inflammatory effects on the gut lining.

Adequate protein and fat at meals Meals that include protein and healthy fats slow gastric emptying, reducing the rapid fermentation that causes post-meal bloating for many people. Meals high in refined carbohydrates alone are a common trigger.

Bone broth and gut-supportive nutrients Glycine, glutamine and collagen found in bone broth support gut lining integrity. Zinc and vitamin A from food sources also play a key role in maintaining intestinal barrier function.

What the evidence is more cautious about

Long-term low-FODMAP diets The low-FODMAP diet was designed as a 6-8 week diagnostic tool, not a permanent eating pattern. Long-term restriction of FODMAPs significantly reduces gut microbiome diversity, which can worsen the underlying gut health issue. It should be a short-term investigation followed by systematic reintroduction.

Cutting out gluten or dairy without proper investigation These eliminations can provide short-term relief but often mask rather than resolve the underlying gut permeability issue. Coeliac disease and lactose intolerance both require proper testing before elimination is recommended long-term.

What most dietary advice misses

Stress is one of the most powerful disruptors of gut function — and it's rarely addressed in a standard dietary consultation. Chronic stress alters gut motility, reduces stomach acid, disrupts the microbiome and increases intestinal permeability. No dietary protocol will fully resolve IBS if chronic stress is unaddressed.

Sleep quality, meal timing, eating environment and chewing properly also have measurable effects on digestion that rarely feature in a GP appointment.

When to consider functional testing

If dietary changes alone haven't provided lasting improvement, gut microbiome testing or a comprehensive stool analysis can be genuinely transformative — providing a precise picture of bacterial balance, inflammatory markers and gut lining health that no elimination diet can give you. This allows for targeted rather than generic intervention.

Bella Dorey is a BANT-registered nutritional therapist specialising in gut and skin health, based in Bury St Edmunds and available online across the UK. If you're struggling with IBS or bloating, book a free 20-minute discovery call to explore how nutritional therapy could help, or find out more about working together here.