What is the best SIBO diet, and how does it differ from a regular IBS diet? Learn about symptoms, risk factors, and management strategies for this debilitating digestive disorder.

Thanks so much to my intern, Yasmine Cheang, RDN, for researching and writing this post!

What is SIBO?

 SIBO stands for small intestinal bacterial overgrowth. As the name suggests, high levels of bacteria, typically seen in the large intestine, also occur in the small intestine. As these bacteria eat undigested carbohydrates in the small bowel and form gas, extreme bloating is commonly experienced (1). 

Photo of a woman in a pink sweater and white tank top holding her belly that's in pain from SIBO symptoms.

Risk Factors

SIBO has been linked to a variety of health conditions. These include small bowel diverticulosis and Crohn’s disease; abdominal surgeries such as gastrojejunostomy; and gastric bypass surgeries for weight loss (1).

In addition, certain conditions result in nerve damage or muscle dysfunction, causing food to move too slowly through our digestive tract– another chance for bacterial growth and SIBO (1)! These conditions include irritable bowel syndrome (IBS), diabetes, hypothyroidism, and scleroderma (1).

Other factors that can also slow transit time are structural problems (e.g., adhesions and strictures in the intestines), medications (e.g., opioids and antidiarrheals), aging, and being female (1).

Also, people with cirrhosis and pancreatic insufficiency have lower bile acid and digestive enzyme levels. As a result, the body cannot digest some food, which feeds gut bacteria. Another SIBO risk factor is immune-related conditions, such as IgA deficiency, HIV, and bacterial peritonitis (1).

Lastly, some evidence has linked proton pump inhibitors (PPI) to SIBO risk, but further research is needed to conclude the relationship. PPIs reduce stomach acid, which generally helps kill harmful bacteria in our food. The low stomach acid level may allow more bacteria to survive when passing through our gut (1).

Symptoms

Symptoms of SIBO resemble those of digestive disorders, especially IBS. IBS patients are prone to have an imbalanced gut microbiome, resulting in SIBO-related issues such as slow gut movement, autoimmunity, and low bile salts (2).

The most typical SIBO symptoms include extreme bloating, distension, diarrhea, abdominal pain, gas, and flatulence (1). In addition, as bacteria in the small bowel can lower nutrient absorption, malnutrition and weight loss can result.

Diagnosis

SIBO is commonly diagnosed with breath testing for increased hydrogen produced by small bowel bacteria. However, methane gas formed by methanogenic archaea (not bacteria) is also measured to indicate IMO (intestinal methanogen overgrowth).

Comparing the two, SIBO is linked to IBS-Diarrhea and IBS with mixed bowel habits, whereas IMO is linked to IBS-constipation as methane gas slows intestinal transit (1,2).

A new breath test also measures hydrogen sulfide, which may cause diarrhea in SIBO patients. Other tests that may aid in the diagnosis, although not commonly used, include blood, fecal fat, and endoscopy for small bowel aspirate and culture. 

SIBO Treatment

As SIBO is often a secondary condition, it is crucial to address the underlying cause, which may be difficult in some cases. Antibiotics, such as Rifaximin, are often used as a first-line SIBO treatment,

As antibiotics also eliminate the good bacteria in the large intestine, probiotics help restore gut microbiota and GI functions in SIBO patients (3). Some studies have shown positive results of probiotics on SIBO treatment and symptoms (4, 5, 6, 7). However, high-quality research on probiotics for SIBO is limited (3). 

In one study, guar gum, a soluble dietary fiber, increased the effectiveness of antibiotics by over 20%. In addition, it serves as a prebiotic to promote beneficial gut bacterial growth, which may improve SIBO outcomes in the long term(8).

Another study shows that herbal antimicrobials may be an alternative to antibiotic treatment. Some examples of the herb combination tested include oregano oil, berberine, wormwood, and thymus Vulgaris. The recommendation of herbal supplements for SIBO patients, however, requires more research (9).

Lifestyle Tips

It is beneficial to regulate the MMC (migrating motor complex) for slow gut motility. MMC is a normal process that helps “sweep” undigested food particles through the small intestine. It is activated by a hormone called motilin, leading to contractions to move foods along the digestive tract (10).

In individuals without IBS or SIBO, it generally takes 90-120 minutes between meals for the MMC process to happen. However, this process is impaired in many individuals with SIBO; thus, prokinetics, which helps gut motility, may help prevent SIBO recurrence. Prescription prokinetics include low-dose erythromycin and prucalopride. Milder OTC prokinetics that may aid gut motility are Iberogast and supplements with ginger or 5-HTP.

In addition, lifestyle changes, as recommended below, may encourage better gut motility.

  • Space meals ~4-5 hours apart to allow the MMC to work.
  • Consider time-restricted feeding if appropriate.
  • Practice mindful eating at mealtimes.
  • Chew food thoroughly to stimulate digestive enzymes (see this post: 8 Tips to Improve Digestion Naturally)
  • Schedule regular meditation sessions into your routine for stress management, or try the Nerva app for gut-directed hypnotherapy.

SIBO Diet

Overhead photo of colorful low FODMAP food for a SIBO diet.
Photo

What diet should you follow if you have SIBO?

In addition to the SIBO treatment and lifestyle habits, dietary changes may help you manage your SIBO symptoms better. Therefore, various specific diets have been suggested for SIBO patients.

Low FODMAP Diet

This is an elimination diet developed at Monash University for people with IBS. High FODMAP foods are avoided for several weeks, then reintroduced to identify trigger foods. Examples of high FODMAP foods are wheat bread/products, cabbage, onion, and apples. They are relatively difficult to digest; therefore, they serve as foods for bacteria to grow! As most IBS patients have SIBO, the overlapping symptoms of these conditions are likely to improve with SIBO eradication. (2).

(Learn more: What is the FODMAP diet? The definitive guide to feeling better with IBS)

Low Fermentation Diet

The low fermentation diet, developed at Cedars Sinai Medical Center, is similar to a low-FODMAP diet, with the idea of avoiding most fermentable carbohydrates, but not all. These foods mainly include those that contain artificial sweeteners, lactose, fructose, and sugar alcohols. Meal spacing is also crucial on this diet. Unfortunately, there is little research on the effectiveness of a low fermentation diet on SIBO. 

Specific Carbohydrate Diet

A specific carbohydrate diet (SCD) may help people with inflammatory bowel diseases (Crohn’s disease and ulcerative colitis) (12). The SCD diet eliminates foods with some types of complex carbohydrates (e.g., all grains, sugars, artificial sweeteners) that can increase inflammation (12). In theory, the SCD helps restore gut microbiome balance (12). However, it may be more restrictive than necessary yet does not limit all fermentable carbohydrates; therefore, it may not benefit SIBO patients. 

Elemental Diet

The elemental diet emphasizes predigested foods to reduce the transit time of food passing through the small intestine. Although this liquid formula diet helps reduce SIBO symptoms, it is generally the last resort treatment option. It can be challenging to follow for the recommended 2-3 weeks, and it doesn’t necessarily address the root cause(s) of SIBO (11). 

So, what SIBO diet should you follow?

The American College of Gastroenterology suggests that SIBO patients limit fermentable foods, fiber, and sweeteners such as sugar alcohols (1). This guideline is very much consistent with a low FODMAP diet. Although more research for its use on SIBO is needed, it is a practical, evidence-based approach for most IBS patients. Therefore, it is generally recommended as a starting point when managing SIBO (1). 

EA’s Note: As the SIBO diet treatment plan varies among individuals, it is best to consult a gastroenterologist and a registered dietitian for personalized guidance to ensure effectiveness and proper nutrition. Here at Spicy RD Nutrition, I aim to help you enjoy the least restrictive diet possible while achieving symptom control. Click here to schedule a consultation!

SIBO Diet Low FODMAP Recipes

colorful healthy new year salad with avocado, tomato, lettuce, pine nuts, and red cabbage.

If you have decided to follow a TEMPORARY low FODMAP diet as part of your SIBO treatment, here are a few recipes for you to try!

Breakfast

(Check out this post for more low FODMAP breakfast recipes!)

Lunch & Dinner

Snacks & Dessert

Also, be sure to check out my low FODMAP Cookbooks & 4-Week Meal Plan!

Any questions about SIBO diet and treatment? Leave a comment and let me know! Managing SIBO can be a long process, but better health IS possible! Schedule a session with me today!

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