Bacteria in your small intestine is normal, but bacterial overgrowth can cause serious problems. Small Intestinal Bacterial Overgrowth, known as SIBO, is a digestive disorder where the small intestine has excess bacteria. Unlike the large intestine, which contains the majority of our gut bacteria, known as the gut microbiota, the small intestine should not have a ton of bacteria. The excess bacteria then ferment with food particles and nutrients in the small intestine and can cause an arrangement of problems. SIBO symptoms mainly affect the gut. Pain in the stomach, diarrhea, bloating, indigestion, and gas can all be symptoms of SIBO¹. It is estimated that more than 15% of Americans and 20% of Canadians are affected by SIBO². 

A proper diet is essential in treating SIBO. The bacteria mainly eat carbohydrates, especially certain fibers, so the recommended diet plans limit carbohydrate intake, limiting the bacteria's food supply and reducing the bacteria. Insoluble fiber is the only carbohydrate that the bacteria don’t eat much of ³.  Insoluble fibers, such as cellulose, are generally poorly fermented by gut microbes, but their presence in the diet increases gut transit rate and thus reduces the amount of time available for colonic bacterial fermentation of non-digested foodstuff. Research has shown that the Low FODMAP Diet, Specific Carbohydrate Diet (SCD), the Gut and Psychology Syndrome Diet (GAPS Diet), or a combination of these along with drinkable probiotics or capsules, are effective in treating SIBO and its symptoms. 

Low FOODMAP Diet

The low FODMAP diet limits the intake of food compounds called FODMAPs, temporarily. These short-chain carbohydrates are poorly absorbed by the small intestine and can cause digestive discomfort. Because this specific diet is very restrictive, it is only recommended as a temporary solution and not a long-term diet. FODMAP stands for Fermentable, Oligosaccharides, Disaccharides, Monosaccharides, and Polyols and are short-chain carbohydrates that are poorly absorbed and fermentable. Common FODMAPs include fructose (sugar in most fruits and vegetables), lactose (sugar in dairy), fructans (a chain of sugars in vegetables and grains), galactans (found in legumes), and polyols (sugar alcohols like sorbitol). 

The low FODMAP diet is a three-phase diet completed over a couple of months. The first phase is a complete restriction of high FODMAP foods. Phase 2 begins introducing different FODMAP groups, one at a time, to figure out which foods trigger symptoms. Phase 3, modifies and adapts the FODMAP diet to create a personalized diet based on an individual’s trigger foods. 

This specific diet has been found to significantly improve symptoms such as abdominal pain and bloating and can be useful for those with SIBO^4,5,6,7..

Specific Carbohydrate Diet

The Specific Carbohydrate Diet (SCD) is a diet that only allows the consumption of simple sugar carbohydrates called monosaccharides. The monosaccharides have a single molecule structure that allows easy absorption through the intestine wall. The complex carbohydrates, disaccharides, and polysaccharides are removed from the SCD diet because they are harder to digest and feed harmful intestinal bacteria, causing them to overgrow and cause inflammation in the gastrointestinal tract. Eating nutrient-rich and easily-digestible foods can improve the balance of bacteria in the gut microbiota⁸. Due to its positive impact on gut health for people with specific health conditions, SCD is also famous for those following a leaky gut syndrome diet. 

Allowed foods on the SCD: Fresh vegetables and fruits (if they have no added sugar), unprocessed meat, fish, and chicken, eggs, homemade yogurts, oils, nuts, some legumes (lentils and lima beans), spices, very dry wine, and the occasional gin, bourbon, or vodka⁹. 

Restricted foods on the SCD: All grains, starchy vegetables (such as potatoes, yams, and corn), added sugar, high lactose dairy (milk and processed cheeses), processed meats and fish, dried and canned fruits, some legumes (soy, canned beans, pinto beans, etc.), beer, coffee, liqueurs, and juice boxes⁹. 

The diet restores the balance of bacteria in the gut microbiota by starving out the harmful bacteria, which reduces inflammation in the gut. 

Because SCD avoids grains and starches, it's also an important diet for those looking for celiac disease foods to avoid. 

Gut and Psychology Syndrome Diet

The Gut and Psychology Syndrome (GAPS) is a condition that establishes a connection between the digestive tract and the brain. The GAPS diet was derived from the SCD diet and focuses on removing foods that are difficult to digest while focusing on nutrient-dense foods to heal the intestinal lining. Created by Dr. Natasha Campbell-McBride, the GAPS protocol is separated into three parts designed to improve the gut lining, rebalance the gut microbiota in the gastrointestinal tract, and support the immune system. 

The diet part of the GAPS protocol is broken into the Introduction diet and the Full GAPS diet. Both diets restrict all grains, commercial dairy, starchy vegetables, and refined carbohydrates. If following the GAPs diet, the majority of food eaten daily should be meats, fish, eggs, fermented dairy, and vegetables (some cooked and some raw). Fruit should be removed from the diet for a few weeks, and when introduced back, should only be eaten as a snack between meals. The GAPS diet focuses on homemade meat stock, soups, stews, and natural fats as staples¹⁰. In the GAPS introduction diet, it is essential to introduce probiotics at the beginning. Think about including an evidence-based probiotic like BIO-K+® to your meal plan. 

What Can You Eat on SIBO Diet?

Following one of the specific SIBO diets, low FODMAP diet, SCD, or the GAPS diet, all have lists of the foods you are allowed to eat with SIBO. The three diets, all differing slightly, will help guide you through what foods they allow. If creating your own plan, be aware of which foods can cause your SIBO symptoms to flare and think about avoiding those and eating more of what your body can tolerate. 

Some carbohydrates, simple sugars such as glucose and fructose, are absorbed quickly before they get fermented so they can be allowed in diets even though they contain fermentable carbohydrates. Ripe fruit, non-starchy vegetables, and nuts are allowed in the diet and also contain nutritional properties. 

What about probiotics? Antibiotics are usually prescribed when treating SIBO to work alongside your diet. When taking antibiotics, you should consider adding a probiotic like BIO-K+® to your daily routine to help restore the balance of your gut microbiota. Probiotics are considered to be “good bacteria” that can be consumed for health benefits. They are made up of single strains or a combination of strains that can improve gut health by decreasing inflammation, strengthening the gut lining, and supporting the immune system¹¹. For these reasons, the best diet for Crohn's disease and SIBO often includes probiotics. 

Research has shown that taking daily SIBO probiotics can alter gut microbiota and reduce SIBO. A small study of patients with irritable bowel syndrome who also had SIBO found that taking a daily probiotic could change the fermentation patterns and reduce SIBO¹¹.  

In one study in 2010, it was found that probiotics can be more effective than antibiotics¹². 82% of the patients that received probiotics reported improvements. Those who took antibiotics only reported a 52% improvement. 

Consider adding an evidence-based supplement such as Bio K+ probiotics to your diet to help heal your gut microbiota and reduce SIBO. 

What Foods Should be Avoided with SIBO?

Fermentable carbohydrates and saccharides should be avoided with SIBO. Fermentable is what the bacteria eat. Limiting fermentable carbohydrates and saccharides will starve the intestinal bacteria and balance out the bacteria in the gut microbiota. Fermentable carbohydrates and saccharides include starch (grains, beans, starchy vegetables), resistant starch (whole grains, seeds, legumes), soluble fiber (grains, beans, nuts, and seeds), and sugar (sweeteners). 

If you follow one of the SIBO diets, low FODMAP diet, SCD, or the GAPS diet, they have lists of specific foods you should avoid. Each diet differs slightly. If creating your own plan, be aware of which foods can cause your symptoms to flare and think about avoiding those. Do not hesitate to consult a registered dietitian before starting a new restrictive diet to avoid any nutritional deficiencies and adapt the plan to your needs.

Can You Eat Potatoes on SIBO Diet?

Depending on which diet you are following, potatoes are either recommended or not recommended to eat. Potatoes are starchy vegetables that are allowed on the low FODMAP diet but on the foods to avoid list for both the SCD and GAPS diet. When creating your own SIBO diet plan, keep track of how potatoes make you feel. If they trigger symptoms, it might be best to avoid them. If your body can tolerate potatoes, then you may want to include them in your diet plan. 

Can You Eat Bananas with SIBO?

The short answer? Yes, you can eat bananas with SIBO. However, the low FODMAP diet, the SCD, and the GAPS diet all differ in banana consumption recommendations. If you are following the low FODMAP diet, an unripe, green banana may be eaten while a ripe banana may not. An unripe banana is low in oligo-fructans and safe for the low FODMAP diet. As the banana ripens, the level of oligo-fructans increases, making the banana no longer low FODMAP compliant¹³. A third or lesser of a ripe banana might be tolerated. On the other hand, the GAPs diet recommends only eating ripe bananas that have brown spots on the skin.  With the SCD, bananas can be consumed as long as they are not canned, and no additional sugar has been added. 

Acids naturally found in bananas can dissolve harmful bacteria and suffocate it out of the body. 

Meal Ideas

Here are some fun SIBO diet recipes to get you started on your new SIBO diet.  

Breakfast: Frittatas filled with eggs, fresh veggies, and ham (if you are eating meat, leave out if not!), fruit smoothies with chia seeds, and homemade yogurt. 

Lunch: Tuna salad on a bed of lettuce, homemade, dairy-free butternut squash soup, and a chopped salad with salmon, hard-boiled eggs and tomatoes. 

Dinner: Almond crusted chicken with broccoli, zucchini noodles with either meatballs and tomato sauce or in a beef stir-fry, and homemade chicken soup. 

Sources: 

• ¹“Small Intestinal Bacterial Overgrowth Syndrome.” World Journal of Gastroenterology, U.S. National Library of Medicine, pubmed.ncbi.nlm.nih.gov/20572300/.
• ²“IBS or Small Intestinal Bacterial Overgrowth?” Gastrointestinal Society, 24 Mar. 2020, badgut.org/information-centre/a-z-digestive-topics/ibs-or-small-intestinal-bacterial-overgrowth/.
• ³Grace, E., et al. “Review Article: Small Intestinal Bacterial Overgrowth – Prevalence, Clinical Features, Current and Developing Diagnostic Tests, and Treatment.” Wiley Online Library, John Wiley & Sons, Ltd, 20 Aug. 2013, onlinelibrary.wiley.com/doi/full/10.1111/apt.12456.
• ⁴“Extending Our Knowledge of Fermentable, Short-Chain Carbohydrates for Managing Gastrointestinal Symptoms.” Nutrition in Clinical Practice : Official Publication of the American Society for Parenteral and Enteral Nutrition, U.S. National Library of Medicine, pubmed.ncbi.nlm.nih.gov/23614962/.
• ⁵“Fermentable Oligosaccharides, Disaccharides, Monosaccharides and Polyols: Role in Irritable Bowel Syndrome.” Expert Review of Gastroenterology & Hepatology, U.S. National Library of Medicine, pubmed.ncbi.nlm.nih.gov/24830318/.
• ⁶“Low FODMAP Diet: The D.I.Y Beginner's Guide (Plus PDFs).” Diet vs Disease, 10 July 2019, www.dietvsdisease.org/diy-low-fodmap-diet/.
• ⁷“Reduction of Dietary Poorly Absorbed Short-Chain Carbohydrates (FODMAPs) Improves Abdominal Symptoms in Patients With Inflammatory Bowel Disease-A Pilot Study.” Journal of Crohn's & Colitis, U.S. National Library of Medicine, pubmed.ncbi.nlm.nih.gov/21172242/.
• ⁸Breaking the Vicious Cycle - The Specific Carbohydrate Diet, www.breakingtheviciouscycle.info/home/.
• ⁹“Specific Carbohydrate Diet (SCD) for Gut Health: Does It Really Help?” Diet vs Disease, 12 Aug. 2019, www.dietvsdisease.org/specific-carbohydrate-diet/.
• ¹⁰“Home.” International Nutrition, Inc., www.gapsdiet.com/home.html.
• ¹¹“Probiotic Effects on Intestinal Fermentation Patterns in Patients with Irritable Bowel Syndrome.” World Journal of Gastroenterology, The WJG Press and Baishideng, 28 Aug. 2008, www.ncbi.nlm.nih.gov/pmc/articles/PMC2742929/.
• ¹²“Comparative Clinical Efficacy of a Probiotic vs. an Antibiotic in the Treatment of Patients with Intestinal Bacterial Overgrowth and Chronic Abdominal Functional Distension: a Pilot Study.” Acta Gastroenterologica Latinoamericana, U.S. National Library of Medicine, Dec. 2010, www.ncbi.nlm.nih.gov/pubmed/21381407.
• ¹³“Update: Bananas Re-Tested!” Bananas and FODMAPs - A Blog by Monash FODMAP | The Experts in IBS - Monash Fodmap, Monash Fodmap, 16 May 2017, www.monashfodmap.com/blog/update-bananas-re-tested/.