What to Eat When You Have SIBO

Small intestinal bacterial overgrowth (SIBO) is a condition where excessive gut bacteria are present in the small intestine. There are different SIBO diets used to help reduce related symptoms and complications, including abdominal bloating, cramping, diarrhea, nutritional deficiencies, weight loss, and more. Though nutritional strategies may be part of a comprehensive treatment plan, there is limited evidence to support any single SIBO diet.

The goal of treating SIBO is not to entirely eliminate gut bacteria, but rather restore a normal balance of it.

Antibiotics, such as Xifaxan (rifaximin), are usually the cornerstone of SIBO treatment. But since SIBO is common in people with other gastrointestinal disorders such as Crohn's disease and irritable bowel syndrome (IBS), addressing these underlying conditions is also important, as they can compound symptoms and encourage bacteria overgrowth in the small intestine.

A SIBO diet can play a role in this by hindering gut bacteria from multiplying, reducing inflammation, and addressing nutritional deficiencies.

Two common SIBO diet treatments include the elemental diet and the low-FODMAP diet. Use of these nutritional protocols may depend on the severity of your symptoms.

An elemental diet is a liquid diet typically used for patients who have compromised digestive systems. However, the diet is getting some new attention as a possible treatment for small intestinal bacterial overgrowth (SIBO). Although it remains somewhat controversial, some research has indicated that an overgrowth of bacteria within the small intestine is responsible for IBS symptoms in some individuals.

The elemental diet is being looked at as a possible adjunct to antibiotics for the following reasons:

• The nutrients in an elemental diet are believed to be completely absorbed in the very first part of the small intestine, which reduces the number of food components available to bacteria.
• Elemental diets have been shown to reduce the number of gut bacteria. Therefore, it is theorized that it may be useful for clearing out bacteria from the small intestine.
• Researchers from the one clinical trial published to date on the subject theorize that the elemental diet may increase the amount of bile released from the gallbladder. This effect would, theoretically, strengthen the small intestine's cleansing wave, reducing bacteria levels.
• These same researchers also propose that the effects of the diet on the immune cells within the lining of the intestines may also serve to eradicate small intestine bacteria.

The diet used in the trial evaluated the effect of nutrition on the level of lactulose in the breath—a measure thought to reflect the presence of excessive amounts of bacteria in the small intestine. Information was also gathered as to the effect of the diet on IBS symptoms.

In the study, 93 IBS patients who had abnormal results on the lactulose breath test (LBT) restricted their diet to an elemental diet formulation for a period of two weeks. Those who continued to show abnormal LBT results after the two weeks were advised to continue for an additional week.

After the first two weeks, normal LBT tests were seen in 80% of patients. The number increased to a total of 85% after inclusion of those who followed the diet for the additional week.

Data was more limited as to the effect of the diet on clinical symptoms, although the study reports increased improvement in IBS symptoms in patients with a normal LBT at the end of the study regardless of IBS sub-type, as compared to those who continued to show elevated LBT results.

There are other studies that have investigated the use of the elemental diet for Crohn's disease, another condition that often accompanies SIBO. There is mixed evidence supporting its use.

The author of one published report notes that compliance with the diet is a barrier. Many patients find the taste of the diet to be unpalatable and others find it unsustainable to adhere to a liquid diet for long enough for the diet to be effective. The author adds, however, that most patients who have experienced difficulties with pharmacological treatments are willing to accept the inconvenience involved in order to see improvement.

The low-FODMAP diet is more commonly used to treat SIBO symptoms. FODMAPs are a group of carbohydrates that include:

• Fermentables
• Oligosaccharides (comprised of fructans and galactans)
• Disaccharides (milk sugar lactose)
• Monosaccharides (fructose)
• Polyols (sugar alcohols such as sorbitol, mannitol, xylitol, and maltitol)

FODMAPs are poorly absorbed by the small intestine and are known to aggravate symptoms of irritable bowel syndrome. Researchers have found that when people with IBS follow a diet low in FODMAPs, many experience significant symptom relief.

With SIBO, two of the various FODMAP types, lactose, and fructose, may be absorbed poorly due to inflammation along the lining of the small intestine. In addition to these two, other non-absorbed FODMAPs may be fermented by the bacteria residing inappropriately in the small intestine, leading to bloating and other digestive symptoms.

The low-FODMAP diet may be helpful for SIBO because the reduction in carbohydrate consumption might "starve" the bacteria in the small intestine.

Some research suggests that the low-FODMAP approach may be beneficial. But more research is needed to know for sure if the treatment is effective enough to be recommended as a standard approach. In 2018, authors of a study published in Gastroenterology Clinics of North America stated that the role of dietary changes in the management of SIBO is still poorly understood. 

Additionally, there is some speculation that the low-FODMAP diet may reduce the effectiveness of antibiotics if a person is taking them for the management of SIBO. Therefore, it is generally recommended that a person eat a normal diet while on the antibiotic and then follow the low-FODMAP diet after the medication course has been completed as a way to prevent future SIBO recurrences.

Your healthcare provider will provide recommendations regarding the best SIBO diet for you. The low-FODMAP diet and elemental diet are possible treatments.

The elemental diet involves complete dietary restriction to a specific liquid formulation. The diet gets its name from the fact that nutrients are introduced into the body in as close to their elemental—or primary— form as possible.

The length of time that you stay on an elemental diet depends on your symptoms and on your compliance with the program. One of the biggest challenges of the elemental diet is giving up solid food.

According to one published report, only about 25% of patients are willing to restrict their nutritional intake to liquid feeding for long enough to see results. But several studies report that those who are compliant see results in two to three weeks.

Some people who are not able to adopt a full elemental diet may, with their doctor's OK, use a partial elemental diet and combine the liquid feeding with foods that are known to be tolerable. A partial elemental diet is sometimes also used for long-term maintenance. But working closely with your healthcare professional is essential to maintain proper nutrition.

The elemental diet is administered as a beverage that you drink, or it may be administered through a feeding tube. The amount of liquid administered is slowly increased over the first few days to reduce unwanted side effects such as diarrhea or abdominal pain.

Each formulation contains nutrients in an easily digestible form. Typical formulations include:

• Essential and non-essential amino acids
• Glucose (an easily digested carbohydrate)
• Vitamins (fat- and water-soluble)
• Minerals
• Electrolytes
• A small amount of fat (less than 1%)

There are different commercial variations of the elemental diet that can be purchased online. The powdered mixes contain only essential nutritional ingredients and provide 150 to 300 calories or more. Your healthcare provider will help you determine how much to use to get adequate nutrition.

No artificial flavor or color is added to elemental diet mixes (which are combined with water), so the beverage has a bland taste that many people find unpalatable. Some experts suggest adding ice to give it texture so it is easier to consume.

Because the elemental diet can be inconvenient and unappetizing, it is generally used as a last resort. However, if SIBO symptoms are severe enough, an elemental diet might be worth it to you.

On this diet, you'll avoid high-FODMAP foods during an elimination phase. At the end of this phase, you slowly introduce each FODMAP type back into your diet—one by one—to accurately pinpoint which FODMAPs cause SIBO symptoms.

The elimination phase can last from two to eight weeks. During this time, you are likely to experience a decrease in symptoms. The next phase, called the reintroduction process, is extremely important. The time needed for this phase varies widely, depending on your symptoms.

Not every FODMAP type is a problem for every person. It is recommended that you pick one FODMAP sub-group at a time to test the effect of each group on your body. Plan to test each group for a week before moving onto the next group.

This diet is not intended for long-term use. Many high-FODMAP foods are actually very good for overall health. A lot of them are considered prebiotics, meaning that they enhance a healthy balance of gut bacteria. Thus, the reintroduction phase and continued re-testing of foods are extremely important to ensure you are eating a varied diet without re-experiencing symptoms.

During the elimination phase, you will avoid foods that are high in FODMAPs. Foods that are non-compliant during this time will contain one of five types of FODMAPs:

• Fructans: Fructans are non-digestible and are found primarily in wheat, many vegetables, and some food additives, including inulin.
• Fructose: Fructose is the sugar found in many fruits, honey, and high-fructose corn syrup.
• Galactans: Also called galactooligosaccharides or GOS, galactans can be found in legumes, including beans, chickpeas, and lentils.
• Lactose: Lactose is the sugar found in milk and other dairy products.
• Polyols: These are sugar alcohols with names that typically end in "- ol." They are found naturally in some fruits, such as blackberries, and vegetables, such as cauliflower and mushrooms, and are often used as artificial sweeteners.

Almost every food group (fruits, vegetables, grains, etc.) contains foods that are high in FODMAPs and foods that are low in FODMAPs.

When following this diet, it is smart to work with a registered dietitian who specializes in SIBO diets to help you choose the best compliant foods for you. Below is a list of sample foods in each group that may be on your compliant or non-compliant list.

Remember that during the elimination phase, you can eat any food that is low in FODMAPs. The list above is just a sample of the foods that are available to you based on information developed by Monash University in Australia, a leader in research on this topic.

The timing of your meals and snacks is not a factor when following both the elimination and reintroduction phase. You can consume food according to a schedule that works best for you. However, since re-introducing FODMAP foods may cause symptoms to occur, you may want to introduce them at a time when you are at home and can be comfortable.

Many people with SIBO have other conditions including celiac disease, chronic pancreatitis, cirrhosis of the liver, Crohn's disease, diverticulitis, diabetes, and other disorders. It is also very common for people with these conditions and with SIBO to experience malnutrition.

For example, fat-soluble vitamins (vitamins A, D, E, and K) may not be properly absorbed if you have SIBO. Those with SIBO may also have an iron deficiency or a vitamin B12 deficiency.

For this reason, it is strongly advised that you work with your healthcare provider and with a nutrition professional to manage SIBO and any underlying condition. Your treatment will be tailored to accommodate your specific symptoms and may include supplementation.

When following the FODMAP diet, most experts recommend keeping a food diary. A simple diary will help you get a better sense of the relationship between the foods that you eat and the symptoms that you experience.

You will also want to gather resources so that you can evaluate the FODMAP content of each food that you choose. The low-FODMAP smartphone app from the researchers at Monash University is a must-have. It can also be helpful to purchase some low-FODMAP cookbooks and find low-FODMAP recipes online.

Lastly, remember that the low-FODMAP diet is not designed to be a permanent eating plan. Many foods that are high in FODMAPs are also foods that are good for your health. Therefore, you will want to be sure to keep re-introducing new foods into your diet at regular intervals to see if your sensitivities have changed. Your food diary will help to guide you through this process.

A SIBO diagnosis can be frustrating, but thankfully the condition is becoming more widely recognized so that proper treatment is easier to find. Work closely with your healthcare team to get personalized advice. Once your nutritional needs are met, you are likely to regain energy and feel more comfortable. Keep in mind that SIBO can fluctuate over time, so you may be able to take a break from treatment for months, or even years, at a time. Be sure to discuss recurring symptoms with your doctor so that flare-ups can be treated promptly.