Small intestinal bacterial overgrowth

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Small intestinal bacterial overgrowth (SIBO) is an excessive population of bacteria in the small intestine. Unlike the large intestine, which is has a very high population of bacteria, the small intestine ordinarily has a very low population of bacteria in healthy people. SIBO is highly prevalent in ME/CFS patients, for whom it appears to cause or worsen symptoms. Treatment often improves ME/CFS symptoms.

Prevalence[edit | edit source]

The rate of a positive lactulose test is low in healthy adults (0 to 20%).[1]

Comorbidities[edit | edit source]

Anecdotal reports suggest a high prevalence of SIBO among CFS patients. One study found 77% of CFS patients had SIBO and eradication lead to decrease in symptoms.[2] Patients with CFS have alterations in microbiota, including lower levels of bifidobacteria and SIBO.[3]

Several studies have shown that up to 84% of patients with irritable bowel syndrome have SIBO[1] and that symptoms improve after treatment[4][5], while others fail to replicate these results[6][7].

One study found that a 100% of fibromyalgia patients tested positive to a lactulose breath test, indicating SIBO, and that the degree of abnormality on the breath test correlated with the amount of pain reported.[4]

Risk factors[edit | edit source]

Diagnosis[edit | edit source]

SIBO is usually diagnosed via a Lactulose breath test. Sometimes it is diagnosed using a bacterial culture. But this is rare due to the difficulty and cost of retrieving a sample from the small intestine. SIBO cannot be diagnosed via stool testing.

Pathophysiology[edit | edit source]

SIBO appears to caused increased intestinal permeability, also known as Leaky Gut. It is believed that this enables lipopolysaccharides from bacteria, food particles, and other undesirable substances to enter the blood stream, ultimately leading to an inflammatory response.

Bacteria commonly implicated in SIBO include Escherichia coli, Streptococcus, Lactobacillus, Bacteroides and Enterococcus.[8] Higher levels of Enterococcus and Stretptococcus have been found in ME/CFS patients.[9]

Health complications[edit | edit source]

The symptoms of SIBO can vary greatly depending on the severity and the species of bacteria populating the small intestine.[7] Symptoms include bloating, abdominal distension, abdominal pain or discomfort, diarrhea, fatigue, weakness, and brain fog.

It causes increased permeability of the small intestine.[citation needed] It can cause malabsorption of nutrients including iron and Vitamin B12, resulting in microcytic anemia or megaloblastic anemia.

Nutritional deficiencies[edit | edit source]

Vitamin B12 malabsorption may be caused by competitive uptake of B12 by bacteria in the small intestine.[1] It can also cause excess folic acid due to synthesis by bacteria in the small bowel.[10]

In severe cases, malabsorption of fat-soluble vitamins (A,D,E and K) due to the deconjugation of bile salts can cause neuropathies and immune dysfunction.

SIBO can also cause carbohydrate and protein malabsorption.[1]

Treatment[edit | edit source]

Treatment generally involves some combination of antibiotics, dietary changes, pro-kinetic agents, and probiotics. Treatment via antibiotics is most common[citation needed].

Antibiotics[edit | edit source]

Any antibiotic that is active in the small intestine may potentially affect the bacterial flora and therefore SIBO. However, certain antibiotics are used preferentially when treatment is explicitly targeting SIBO. These antibiotics may be synthetic or herbal, though synthetic antibiotics appears to be used most often.

Synthetic[edit | edit source]

  • Rifxaimin is the most commonly used antibiotic used for SIBO treatment. It is effective on hydrogen producing bacteria, but not methane producing bacteria. Only a small percentage of the drug is absorbed by the body, and its activity is mostly limited to the small intestine. [11]
  • Neomycin is sometimes given in addition to Rifaximin when methane-producing bacteria are present. [12] However, one study comparing two herbal formulations to standard treatment found herbs to be as or more effect as antibiotics for eradicating SIBO.[13]
  • Metronidazole

Herbal[edit | edit source]

Diet[edit | edit source]

Diets have been used and/or shown to be helpful in treating or controlling SIBO include:

Pro-kinetic Agents[edit | edit source]

Experts also recommend the use of prokinetic drugs or herbs for those for whom dysmotility is an issue.[1] These agents include:

Probiotics[edit | edit source]

The role of probiotics in treatment is controversial.

One school of thought is that SIBO is not due to a "bad" bacteria, but rather a simple overgrowth of ordinary / healthy bacteria. Therefore, it would follow that probiotics would be counterproductive to treating and managing SIBO.

Another school of thought is that SIBO is caused or worsened by the presence of a "bad" bacteria, or a bad mix of bacteria. Therefore, it would follow that probiotics that increase the level of "good" bacteria, or promote a healthier mix of bacteria, would be helpful in treating or managing SIBO. Lactobacillus casei has been found to improve breath hydrogen scores after six weeks of treatment.[14] There is also evidence for VSL #3 in the treatment of SIBO.[15] However, some probiotics may exacerbate SIBO, in particular those containing D-Lactate producing strains.

Increasing Stomach Acid[edit | edit source]

In cases where SIBO is caused by low stomach acid, treatment may include dietary supplements that increase stomach acid, such as Betaine Hydrochloride.

See also[edit | edit source]

Learn more[edit | edit source]

References[edit | edit source]

  1. 1.00 1.01 1.02 1.03 1.04 1.05 1.06 1.07 1.08 1.09 1.10 Dukowicz, AC; Lacy, BE; Levine, GM (February 2007), "Small Intestinal Bacterial Overgrowth", Gastroenterology & Hepatology, 3 (2): 112–122, PMID 21960820
  2. Pimentel, M; Hallegua, D; Chow, EJ; et al. (April 1, 2000), "Eradication of small intestinal bacterial overgrowth decreases symptoms in chronic fatigue syndrome: A double blind, randomized study", Gastroenterology, 118 (4): 414, doi:10.1016/S0016-5085(00)83765-8
  3. Logan, Alan C; Venket Rao, A; Irani, Dinaz (June 2003), "Chronic fatigue syndrome: lactic acid bacteria may be of therapeutic value", Medical Hypotheses, 60 (6): 915–923, PMID 12699726
  4. 4.0 4.1 Pimentel, M; Wallace, D; Hallegua, D; et al. (April 2004), "A link between irritable bowel syndrome and fibromyalgia may be related to findings on lactulose breath testing", Annals of the Rheumatic Diseases, 63 (4): 450–452, doi:10.1136/ard.2003.011502, PMID 15020342
  5. Lin, HC (August 18, 2004), "Small intestinal bacterial overgrowth: A framework for understanding irritable bowel syndrome", JAMA, 292 (7): 852–858, doi:10.1001/jama.292.7.852
  6. Walters, B; Vanner, SJ (July 2005), "Detection of bacterial overgrowth in IBS using the lactulose H2 breath test: comparison with 14C-D-xylose and healthy controls", The American Journal of Gastroenterology, 100 (7): 1566–1570, doi:10.1111/j.1572-0241.2005.40795.x, PMID 15984983
  7. 7.0 7.1 Parisi, Giancarlo; Leandro, Gioacchino; Bottona, E; et al. (November 2003), "Small intestinal bacterial overgrowth and irritable bowel syndrome", The American Journal of Gastroenterology, 98 (11): 2572–2573-2574, doi:10.1111/j.1572-0241.2003.08686.x, PMID 14638371
  8. Bouhnik, Yoram; Alain, Sophie; Attar, Alain; et al. (May 1999), "Bacterial populations contaminating the upper gut in patients with small intestinal bacterial overgrowth syndrome", The American Journal of Gastroenterology, 94 (5): 1327–1331, doi:10.1111/j.1572-0241.1999.01016.x
  9. Sheedy, John R; Wettenhall, Richard EH; Scanlon, Denis; et al. (July 2009), "Increased d-lactic Acid intestinal bacteria in patients with chronic fatigue syndrome", In Vivo, 23 (4): 621-8, PMID 19567398
  10. Camilo, E; Zimmerman, J; Mason, JB; et al. (April 1996), "Folate synthesized by bacteria in the human upper small intestine is assimilated by the host", Gastroenterology, 110 (4): 991–998, PMID 8613033
  11. Bures, Jan; Cyrany, Jiri; Kohoutova, Darina; et al. (June 28, 2010), "Small intestinal bacterial overgrowth syndrome", World Journal of Gastroenterology : WJG, 16 (24): 2978–2990, doi:10.3748/wjg.v16.i24.2978, PMID 20572300
  12. Low, Kimberly; Hwang, Laura; Hua, Johnson; Zhu, Amy; Morales, Walter; Pimentel, Mark (September 2010). "A combination of rifaximin and neomycin is most effective in treating irritable bowel syndrome patients with methane on lactulose breath test". Journal of Clinical Gastroenterology. 44 (8): 547–550. doi:10.1097/MCG.0b013e3181c64c90. ISSN 1539-2031. PMID 19996983.
  13. Chedid, Victor; Dhalla, Sameer; Clarke, John O; et al. (May 2014), "Herbal Therapy Is Equivalent to Rifaximin for the Treatment of Small Intestinal Bacterial Overgrowth", Global Advances in Health and Medicine, 3 (3): 16–24, doi:10.7453/gahmj.2014.019, PMID 24891990
  14. Barrett, Jacqueline S; Canale, Kim EK; Gearry, Richard B; et al. (August 28, 2008), "Probiotic effects on intestinal fermentation patterns in patients with irritable bowel syndrome", World Journal of Gastroenterology : WJG, 14 (32): 5020–5024, doi:10.3748/wjg.14.5020, PMID 18763284
  15. Meier, Rémy; Burri, Emanuel; Steuerwald, Michael (September 2003), "The role of nutrition in diarrhoea syndromes", Current Opinion in Clinical Nutrition and Metabolic Care, 6 (5): 563–567, doi:10.1097/01.mco.0000087972.83880.d3, PMID 12913674

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From MEpedia, a crowd-sourced encyclopedia of ME and CFS science and history.