What is SIBO?

Small intestinal bacterial overgrowth (SIBO) is a medical condition that has diverse co-morbidities that appear with a variety of symptoms that can be primarily gastrointestinal, or not, due to an excessive amount of overgrowth of bacteria inside of the small intestine.

What are the symptoms of SIBO?

SIBO can have many symptoms that replicate other diseases. It is important to rule out the root cause of what may be causing you to feel any of the following concerns with the help of a medical practitioner and/or your Registered Dietitian.

  • Gas

  • Bloating

  • Diarrhea

  • Swollen or distended abdomen

  • Constipation

  • Nausea

  • Fatty Stool

  • Malnutrition from malabsorption

  • Unintentional weight loss

  • Abdominal pain and/or cramping

  • Indigestion

  • Fatigue

  • Loss of appetite

  • Uncomfortable feeling of fullness after eating (abdominal fullness)

How is SIBO diagnosed?

SIBO can be diagnosed a few different ways. Some specialists will perform a breath analysis, an example of this being the lactulose breath test. Doctors may also want to perform some kind of endoscopy to extract a sample or small intestine aspirate, and then test it in a fluid culture.

According to Jin Shi et al. “The gold standard test for SIBO is a duodenal aspirate culture to measure microbial density in the duodenum” (8). Bloodwork is also an important tool to see if you are missing any vital nutrients. SIBO patients often experience vitamin and mineral deficiencies, as well as malabsorption — especially if they’ve been sick for a while. Another option for testing is a Fecal Fat Test. This test looks for undigested fat and/or bile salts in stool. This indicates poor digestion.

Vitamins & minerals at risk of being depleted in SIBO patients, according to Today’s Dietitian: omega-3 fatty acids, vitamins A, D, E, and K, coenzyme Q-10, beta-carotene, as well as reduce stores of vitamin B12 and iron.

What treatments exist for SIBO?

There are few treatments that exist for treating SIBO, however the ones that do exist tend to be mostly successful.

 

Antibiotics

One of the most researched treatment options is antibiotics. There is no standard time length or dosage value, though. This is because every SIBO case is different and may have an underlying issue that needs treatment as well. There are also cases where there is no cure for the root cause of SIBO, in which the patient is usually placed on a low dose antibiotic cocktail, there is still more research that can be done in this area. Rifaximin is the most popular antibiotic drug prescribed to SIBO patients, although ciprofloxacin, norfloxacin, and metronidazole are also given. 

 

Other options

Much of the time if there is an underlying cause that can be cured, it is done alongside antibiotic treatment. It is often suggested to avoid certain medications that can cause a delay in digestion, avoidance of proton pump inhibitors (e.g. prevacid, omeprazole, lansoprazole), reduce or avoid opioids, manage intestinal adhesions, and also managing the intake of high glycemic foods (6). This is an area where nutritional intervention can be really helpful. There are limited dietary recommendations known to manage SIBO, however these options will be discussed further along in the article. If nutritional deficiencies become too severe for normal diet management total parenteral nutrition (TPN) can be prescribed. This is known as nutrition through a vein. 

 

Functional medicines/nutrition

 

There are not enough studies to verify any other alternative or functional medicine. The few that exist include options like: prokinetic agents, probiotics, and herbal combinations. Some studies have shown promising evidence in the antimicrobial properties of a variety of herbs such as black cumin, cinnamon, thyme, garlic, rosemary, mustard, cloves, and rosemary (7). 

 

All in all, SIBO can truly only be cured or managed with the help of a medical professional like a Registered Dietitian or GI specialist.

What diseases/co-morbidities are associated with SIBO?

Having these diseases or health concerns does not mean you definitely have Small Intestinal Bacterial Overgrowth. However, if you are experiencing symptoms like diarrhea, abdominal pain, and bloating with no other explanation, it is worth checking into (8). You may be at greater risk for SIBO if you have any of the following health issues as they are associated with one another and it is highly recommended to be seen by a knowledgeable practitioner to be evaluated for any specific concern. It is best not to attempt to self-diagnose.

  • Irritable bowel syndrome

  • Inflammatory bowel disease

  • Motility disorders

  • Chronic pancreatitis

  • Cirrhosis

  • Various immunodeficiencies

  • H.pylori

  • Papustular rosacea

  • Spinal cord injury with deep vein thrombosis, which is associated with pediatric obesity

  • Nonalcoholic fatty liver disease (NAFLD)

Contributing factors

Certain types of foods are known to increase symptoms associated with SIBO. These foods primarily consist of foods that are high in carbohydrates as they ferment in the small bowel when SIBO is present. These high carbohydrate foods are things like starchy vegetables, fruits, sugars, grains, and dairy. Some foods might trigger a response and others may not. It is on an individual basis.

Some diseases or health conditions can contribute to SIBO. They are listed below: 

  • Diverticulitis

  • Adhesions or scar tissue

  • Ileocecal valve loss

  • Diabetes

  • Celiac disease

  • Crohn’s disease

  • Low stomach acid associated with gastric bypass surgery or prolonged use of medications

  • Small intestine dysmotility (examples include: gastroparesis, intestinal pseudo-obstruction, or hypothyroidism)

  • Structural problems in the small intestine like small bowel diverticulosis or obstructions

Excessive usage of certain medications can also impact your risk of developing SIBO. Excessive usage of opioids is a predisposing condition, as well as overuse of gastric acid suppressants like antacids or proton pump inhibitors (1).

Diet/food recommendations

Diet recommendations do not really vary.

The majority of medical professionals that recommend a diet change to manage SIBO typically will recommend a dairy or lactose free diet due to the fact some people develop lactose intolerance after recovering from SIBO because of the intestinal damage the bacterial overgrowth can cause. The ketogenic diet has been recommended to get rid of high carbohydrate foods and reduce intestinal fermentation. The same idea has been said for the low FODMAP diet.

Some herbal medicine has also been suggested for SIBO patients, however there is not very much research associated with herbal medicine and SIBO. In one study (7), it was found that going from a high fiber diet to a low fiber and high simple sugar diet triggered functional gastrointestinal disorders and lowered the small intestine microbial diversity and raised the permeability of the small intestine. This can explain why it is beneficial to consume a high fiber diet, however there are cases of SIBO even in people that consume a plentiful amount of fiber.

Probiotics?

Probiotics (and prebiotics) have been at the forefront of gut health for the past few years. Some studies find that the use of probiotic use in SIBO is helpful in reducing symptoms, such as abdominal pain, bloating, and diarrhea (9, 10, 11).

There was a comprehensive review done in 2020 regarding probiotic use and SIBO. The review found that it is possible that probiotic use may contribute to an overgrowth of a certain bacteria that is prolific in SIBO (12). However, there needs to be many more studies, done on a large scale, to determine if this is continued to be found. Plus, many individuals who end up taking probiotics for SIBO or with SIBO find that things get worse before they get better, and they report that after continued usage, symptoms usually improve. It’s also good to note, that too much of a good thing is usually just too much. So if you’re currently taking probiotics, get advice from your physician or dietitian regarding the dosage you’re currently consuming.

This post was co-written by aspiring dietitian Adrianna L.

References:

  1. Achufusi, Ted George O et al. “Small Intestinal Bacterial Overgrowth: Comprehensive Review of Diagnosis, Prevention, and Treatment Methods.” Cureus vol. 12,6 e8860. 27 Jun. 2020, doi:10.7759/cureus.8860

  2. Lee, Seok-Hoon et al. “The Therapeutic Effect of a Multistrain Probiotic on Diarrhea-Predominant Irritable Bowel Syndrome: A Pilot Study.” Gastroenterology research and practice vol. 2018 8791916. 6 Dec. 2018, doi:10.1155/2018/8791916

  3. Phan, Joann et al. “Alterations in Gut Microbiome Composition and Function in Irritable Bowel Syndrome and Increased Probiotic Abundance with Daily Supplementation.” mSystems vol. 6,6 (2021): e0121521. doi:10.1128/mSystems.01215-21

  4. Leventogiannis, Konstantinos et al. “Effect of a Preparation of Four Probiotics on Symptoms of Patients with Irritable Bowel Syndrome: Association with Intestinal Bacterial Overgrowth.” Probiotics and antimicrobial proteins vol. 11,2 (2019): 627-634. doi:10.1007/s12602-018-9401-3

  5. Rao, Satish S C, and Jigar Bhagatwala. “Small Intestinal Bacterial Overgrowth: Clinical Features and Therapeutic Management.” Clinical and translational gastroenterology vol. 10,10 (2019): e00078. doi:10.14309/ctg.0000000000000078

  6. Ren, Xuetong et al. “Chinese herbal medicine for the treatment of small intestinal bacterial overgrowth (SIBO): A protocol for systematic review and meta-analysis.” Medicine vol. 99,51 (2020): e23737. doi:10.1097/MD.000000000002373

  7. Saffouri, George B et al. “Small intestinal microbial dysbiosis underlies symptoms associated with functional gastrointestinal disorders.” Nature communications vol. 10,1 2012. 1 May. 2019, doi:10.1038/s41467-019-09964-7

  8. Shi, Jin et al. “Effect of Combined Live Probiotics Alleviating the Gastrointestinal Symptoms of Functional Bowel Disorders.” Gastroenterology research and practice vol. 2020 4181748. 17 Sep. 2020, doi:10.1155/2020/4181748

  9. Chen, Wei Chung, and Eamonn MM Quigley. “Probiotics, prebiotics & synbiotics in small intestinal bacterial overgrowth: opening up a new therapeutic horizon!.” The Indian Journal of Medical Research 140.5 (2014): 582.

  10. Kwak, Dong Shin, et al. “Short-term probiotic therapy alleviates small intestinal bacterial overgrowth, but does not improve intestinal permeability in chronic liver disease.” European Journal of Gastroenterology & Hepatology 26.12 (2014): 1353-1359.

  11. Liang, Sufang, et al. “Effect of probiotics on small intestinal bacterial overgrowth in patients with gastric and colorectal cancer.” Turk J Gastroenterol 27.3 (2016): 227-232.

Achufusi, Ted George O., et al. “Small Intestinal Bacterial Overgrowth: Comprehensive Review of Diagnosis, Prevention, and Treatment Methods.” Cureus 12.6 (2020).

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