How a SIBO Diet Is Used to Support Gut Balance

Small intestinal bacterial overgrowth (SIBO) is a digestive condition in which bacteria in the small intestine grow in larger numbers than normal. It can be linked to gas, bloating, diarrhoea, constipation and problems absorbing nutrients. Eating in a way that suits the individual is often discussed as part of the overall management of SIBO. So what is a SIBO diet? Which foods are usually eaten and which are limited? How can you look after your gut health? Here is an overview of how a SIBO diet is used to support gut balance.

1. What is SIBO and what are its symptoms?

SIBO is a condition in which bacteria that are normally present in small numbers in the small intestine grow excessively and can cause digestive discomfort.

Common symptoms associated with SIBO:

• Excessive gas and bloating
• Diarrhoea or constipation (or alternating between the two)
• Abdominal pain and cramps
• Food intolerances (particularly lactose and gluten sensitivity)
• Weight loss or difficulty gaining weight
• Greasy stools or stools containing undigested food
• Vitamin and mineral deficiencies (particularly B12 and iron)

Tip: SIBO is diagnosed by a doctor, using tests such as a breath test. If you have these symptoms, please see your doctor for an assessment.

2. What is a SIBO diet and how is it used?

A SIBO diet is an eating plan that limits certain foods with the aim of reducing the foods that bacteria in the gut can ferment, in order to ease symptoms and make digestion more comfortable. It is usually carried out under the guidance of a doctor and dietitian.

A SIBO diet is often described in three phases:

1) Elimination phase (first 4 to 6 weeks)
Highly fermentable carbohydrates are removed from the diet. The aim is to reduce the load of fermentable food available to the bacteria in the gut.

2) Reintroduction phase (4 to 6 weeks)
Small amounts of fermentable carbohydrates are added back to the diet. Tolerance is tested to see which foods make symptoms worse.

3) Maintenance and balance phase
Prebiotic and probiotic foods that support the gut are added back as tolerated, in order to keep eating varied and support gut health.

Tip: following this diet under professional guidance helps you manage it safely and avoid unnecessary restriction.

3. Foods usually limited on a SIBO diet

The foods that may worsen SIBO symptoms are usually highly fermentable carbohydrates.

High-FODMAP and fermentable foods that are usually limited:

1) Highly fermentable carbohydrates

• Onion, garlic, leeks
• Cauliflower, broccoli, cabbage, Brussels sprouts
• Pulses (lentils, chickpeas, beans, peas)
• Apples, pears, watermelon, mango
• Grains containing gluten (wheat, rye, barley)

2) Products containing lactose

• Milk, yoghurt, kefir, cream, cheese

3) Sugar and processed foods

• Refined sugars, sweeteners, fizzy drinks
• Ready-packaged foods, cakes, biscuits

Tip: limiting fermentable foods is a key part of this approach, but only for as long as your dietitian advises, because many of these foods are also nutritious.

4. SIBO-friendly foods

To ease symptoms, gut-friendly, low-fermentable foods are generally chosen.

Low-FODMAP and SIBO-friendly foods:

1) Protein sources

• Chicken, turkey, red meat, fish
• Eggs

2) Less fermentable vegetables

• Carrot, courgette, potato, cucumber, spinach
• Lettuce, green beans

3) Low-FODMAP fruits

• Strawberries, blueberries, kiwi
• Banana, lemon, orange

4) Healthy fats and carbohydrates

• Olive oil, coconut oil
• White rice, quinoa, gluten-free oats

Tip: to be gentler on your digestive system, you can use light cooking methods such as boiling and steaming.

5. Supplements

Some people with SIBO are advised by their doctor to take supplements alongside dietary changes. Which supplements, if any, suit you, and in what form, should be decided only with your doctor, as some of them can make symptoms worse or interact with medication. Please do not start any supplement or probiotic on your own.

6. A sample day for a SIBO-friendly, low-FODMAP diet

Sample one-day low-FODMAP menu:

Tip: everyone's gut is different, so keeping a food diary can help you see which foods make your symptoms worse.

Looking after your gut health with a SIBO diet

• A low-FODMAP approach may help ease symptoms in some people when followed under professional guidance.
• Reintroducing foods in time helps you keep a varied diet and support gut balance.
• Watching your eating carefully helps you spot the foods that trigger your symptoms.

Remember: a SIBO diet needs an individual eating plan. To find the right approach, please work with a dietitian and a gastroenterologist.

This article is for general information only; please consult your doctor and dietitian about your own situation.