Irritable Bowel Syndrome (IBS) is a functional digestive condition that affects how the gut moves and responds to food. Common symptoms include bloating, abdominal pain, gas, constipation, diarrhea, or a mix of both. While IBS doesn’t cause structural damage to the gut, symptoms can significantly affect quality of life.
When it comes to IBS, what you eat matters — but not in the same way as other conditions. Research shows that avoiding personal trigger foods is more important than following a specific macronutrient ratio.
Do macros matter for IBS?
Unlike some metabolic conditions, IBS symptoms are driven more by food tolerance than by exact macro percentages. That said, having a general structure can still help support digestion and energy levels.
A flexible macro framework often used in IBS care:
- Protein: ~20–25%
- Carbohydrates: ~40–50% (with a focus on low-FODMAP sources)
- Fat: ~23–30%
Importantly, studies show that macro distribution is less predictive of symptom improvement than identifying and avoiding trigger foods.
Supporting evidence:
- IBS symptom control is more strongly linked to trigger avoidance than macro ratios
- https://pubmed.ncbi.nlm.nih.gov/31223623/
Protein: helpful, but not too high
Protein is important for satiety and meal balance, but very high protein intakes may worsen symptoms in some people, particularly those with constipation-predominant IBS (IBS-C).
- Moderate protein intake (around 20–25% of calories) is generally better tolerated
- Extremely high protein diets may contribute to slower gut motility in some individuals
Supporting evidence:
- Higher protein intake associated with constipation-predominant symptom patterns
- https://pubmed.ncbi.nlm.nih.gov/38651659/
Carbohydrates: focus on FODMAP content, not elimination
Carbohydrates are not the problem in IBS — poorly absorbed fermentable carbohydrates are.
- A low-FODMAP approach reduces symptoms by limiting fermentable sugars that feed gas-producing gut bacteria
- This approach is most effective when used short-term, followed by structured reintroduction
Fat: moderate and consistent
Fat doesn’t need to be avoided in IBS, but very high-fat meals can worsen symptoms such as cramping or urgency in some people.
- A moderate fat intake (23–30%) tends to be better tolerated
- Spreading fat intake evenly across meals may reduce symptom flares
Guiding dietary principles for IBS
Low-FODMAP (short-term tool)
Low-FODMAP diets are one of the most well-studied and effective dietary strategies for IBS symptom reduction, especially for bloating, gas, and abdominal pain.
- Intended as a short-term elimination phase, not a lifelong diet
- Best done with guidance to avoid unnecessary restriction
Supporting evidence:
Mediterranean-style eating (long-term pattern)
Once trigger foods are identified, transitioning toward a Mediterranean-style eating pattern supports gut health, nutrient adequacy, and overall well-being.
This pattern emphasizes:
- Vegetables and fruit (as tolerated)
- Whole grains and legumes (low-FODMAP choices initially)
- Olive oil, nuts, and seeds
- Lean proteins and fish
- Minimal ultra-processed foods
Supporting evidence:
- https://pubmed.ncbi.nlm.nih.gov/40806081/
- https://pubmed.ncbi.nlm.nih.gov/41144975/
- https://pubmed.ncbi.nlm.nih.gov/40273380/
Therapeutic ingredients that may help IBS symptoms
These foods and nutrients are not cures, but research suggests they may help reduce symptoms when used appropriately.
Soluble fibre (generally beneficial)
Soluble fibre is often better tolerated than insoluble fibre in IBS.
Examples include:
- Psyllium
- Oats
- Ground flaxseed
Benefits may include improved stool consistency and reduced abdominal discomfort.
Supporting evidence:
Ginger
Ginger may help with:
- Bloating
- Cramping
- Nausea
Often used as an adjunct, not a standalone treatment.
Supporting evidence:
Curcumin (from turmeric)
Curcumin has anti-inflammatory properties and may help with overall symptom burden in some people with IBS.
Supporting evidence:
Fennel
Fennel has traditionally been used for:
- Gas
- Bloating
- Cramping
Some clinical evidence supports its use in IBS symptom management.
Supporting evidence:
Meal guidelines: vegan & plant-based IBS considerations
Vegan and plant-based diets can be compatible with IBS, but they require careful planning, especially during the elimination phase.
- A low-FODMAP vegan approach may be used for up to 6 weeks
- This should be done with a healthcare provider to:
- Prevent unnecessary restriction
- Maintain adequate protein and nutrient intake
- Properly reintroduce foods