IBS Is No Joke: IBS from Small Intestine Bacterial Overgrowth (SIBO); Causes and Treatment

IBS or irritable bowel syndrome is a common problem affecting between 7% and 10% of the world's population.  IBS affects twice as many women as it does men, and most people who suffer from it don't see a doctor for their symptoms.  The symptoms include pain, gas, cramping or bloating, and diarrhea or constipation. Every case of IBS is different, but symptoms are thought to be triggered by certain foods, stress, hormonal changes, or medications.

Ordinary standard of care includes dietary restrictions and lifestyle changes, stress-management techniques, In some severe cases, medicine for pain, diarrhea, or constipation is needed to give the IBS patient comfort. There are also other natural treatments for IBS.  The following video details some more holistic solutions for IBS:

Often, uncovering and removing hidden food intolerances, adding mindfulness to a rushed approach to meals, or restoring production of digestive acid or enzymes is the key to resolving IBS. But what about those cases in which bloating, abdominal pain, constipation, or diarrhea remain unchanged?
After serious diagnoses are ruled out, what could be another source of these IBS symptoms?

Small intestine bacterial overgrowth (SIBO) is a condition in which abnormally large numbers of symbiotic bacteria are present in the small intestine. SIBO is a common cause of IBS – in fact it is involved in over half the cases of IBS and as high as 84% in one study using breath testing as the diagnostic marker.1,2  Eradication of this overgrowth leads to a 75% reduction in IBS symptoms.4 Bacterial overgrowth leads to impairment of digestion and absorption and produces excess quantities of hydrogen and/or methane gas. These gases are not produced by human cells but are the metabolic product of fermentation of carbohydrates by intestinal bacteria. When symbiotic bacteria (oral, small intestine or large intestine) multiply in the small intestine to the point of overgrowth, IBS is likely to occur in that patient. Hydrogen/methane breath testing is the most widely used method of testing for this overgrowth.  hydrogen/methane breath testing is the most common method of assessing SIBO. Instrumentation is available from Quintron Instrument Company in Milwaukee, Wisconsin. It provides a device called the Breathtracker, which is used to measure these gases following a 24-hour prep diet and an overnight fast.  Stool sample testing is of no value in diagnosing SIBO.

Symptoms of SIBO include:

•    bloating/ abdominal gas 

•    flatulence, belching

•    abdominal pain, discomfort, or cramps

•    constipation, diarrhea or a mixture of the two

•    heartburn

•    nausea

•    malabsorption: steatorrhea, anemia

•    systemic symptoms: headache, joint/muscle pain, fatigue, rosacea

Other diseases associated with SIBO include hypothyroidism, lactose intolerance, Crohn's disease, systemic sclerosis, celiac disease, chronic pancreatitis, diabetes with autonomic neuropathy, fibromyalgia and chronic regional pain syndrome, hepatic encephalopathy, nonalcoholic steatohepatitis, interstitial cystitis, restless leg syndrome, and acne rosacea.5–17 

There are two main pathophysiological issues involved in SIBO and related to IBS. 

First, bacteria can ferment food meant for the host simply by their inappropriate location in the small intestine, which allows them premature exposure to host nutrition. Bacterial fermentation produces hydrogen and/or methane gas. Bacterial gas leads to the IBS symptoms of bloating, pain, altered bowel movements, eructation and flatulence (Figure 1). The quantity of gas may be extensive, causing bloating/distention.26 Excess gas can then exit the body as flatulence or eructation. The intestines are sensitive to pressure and therefore the pressure of distention can lead to abdominal pain. In addition, visceral hypersensitivity, a feature of IBS, may create a lower threshold for pain/discomfort and a hyperresponsiveness of muscular contraction in response to the gas, leading to cramps in some.27,28 The gases also affect bowel motility with hydrogen having a greater association with diarrhea and methane having an almost exclusive association with constipation.29,30 Methane has been shown to slow gastrointestinal motility by 59% in animal studies, and the volume of methane overproduction correlates with the severity of constipation.31,32 Therefore when both hydrogen and methane are present, diarrhea, constipation, or a mixture of both can be present based on the relative amounts of gases.29 The bacterial consumption and uptake of host nutrients, such as B12 and iron, can lead to macrocytic and/or microcytic anemia or chronic low ferritin, in addition to general malabsorption and malnutrition in more severe cases.8,33 The increased motility of diarrhea may also induce malabsorption. Finally, continuous fermentation of host nutrition by repeated exposure to daily meals, perpetuates bacterial overgrowth and its symptoms, creating a vicious cycle (Figure 1).

Figure 1

Second, bacteria damage the digestive and absorptive structure and function of the small intestine. This occurs because, unlike the large intestine, the small intestine is not designed for large colonization. The damage leads to both gastrointestinal and systemic symptoms.   Key damaging factors are: bacterial deconjugation of bile, which creates fat malabsorption (steatorrhea, fat-soluble vitamin deficiency); bacterial digestion of disaccharide enzymes, which furthers carbohydrate malabsorption, fermentation, and gas; and increased intestinal permeability (leaky gut), which leads to systemic symptoms and allergies.34–38

PREVENTION AND HOLISTIC TREATMENTS FOR SIBO

An important protective mechanism against SIBO is proper small intestine motility because stasis promotes bacterial growth.18 Also key in prevention is normal gastric HCl, pancreatic, and gall bladder secretions, since hydrochloric acid, enzymes, and bile are bactericidal/static.19

Hydrochloric acid or herbal bitter supplements encourage hydrochloric acid (HCl) secretion and may be used to decrease the load of incoming bacteria.39 When considering HCl supplementation, Heidelberg testing for HCl level and function is the gold standard and allows individualization of dosing.  

Probiotics are a controversial intervention in SIBO because lactobacilli have been cultured in SIBO and there is concern about adding to the bacterial overload, particularly in this situation of dysfunctional MMC.25 Despite this, the few studies that have focused directly on SIBO have shown good results, with a SIBO eradication rate of 47% from Bacillus clausii as the only treatment, and a clinical improvement rate of 82% from Lactobacillus casei and plantarum, Streptococcus faecalis, and Bifidobacter brevis (Bioflora) as the only treatment.40.41 Probiotic yogurt containing Lactobacillus johnsonii normalized cytokine responses – reducing the low-grade chronic inflammation found in SIBO, after 4 weeks.42 

A key point for the use of probiotic supplements in SIBO is to avoid prebiotics as main ingredients. Prebiotics are fermentable food for bacteria that can exacerbate symptoms during active SIBO and encourage bacterial growth post SIBO. Common prebiotics found in probiotic supplements include FOS (fructooligosaccharide), inulin, arabinogalactan, and GOS (galactoligosaccharide). Prebiotics may be tolerated in small amounts used as base ingredients, but this depends on the individual.

Brush border healing supplements may be given to assist the repair of small intestine tissue. While mucilaginous herbs are traditionally employed for this purpose (licorice, slippery elm, aloe vera, marshmallow), their use is controversial post SIBO, due to their high level of mucopolysaccharides, which could encourage bacterial regrowth. Specific nutrients that have been used to repair damaged samll intestine tissue include colostrum: 2–6 g q.d., L-glutamine: 375 mg–1500 mg q.d., zinc carnosine: 75–150 mg q.d., vitamins A and D, often given as cod liver oil: 1 Tbs q.d., curcumin: 400 mg–3 g q.d., resveratrol: 250 mg–2 g q.d., glutathione (oral liposomal): 50–425 mg q.d. or glutathione precursor N-acetylcysteine 200–600 mg q.d. Supplements are given for one to three months, though may be continued long term for general benefit. 

The recommended diet is (Specific Carbohydrate Diet or Gut and Psychology Syndrome Diet) for all SIBO patients. 41,42,43 Since bacteria use carbohydrates as their energy source and ferment them to gas, a low-carbohydrate diet can directly reduce symptoms by decreasing the amount of gas produced.44Reducing carbohydrates may also reduce the overall bacterial load as the food supply shrinks, though formal studies to validate this are lacking. These diets decrease polysaccharides, oligosaccharides, and disaccharides by eliminating all grains, starchy vegetables, lactose, sweeteners other than honey, and in the beginning, beans. Many patients experience a rapid and significant decrease in symptoms after starting a SIBO diet. The Specific Carbohydrate Diet (SCD) has been reported to have an 84% success rate for inflammatory bowel disease, a condition commonly associated with SIBO.44,45 

REFERENCES

1.   Peralta S et al. Small intestine bacterial overgrowth and irritable bowel syndrome-related symptoms: experience with Rifaximin. World J Gastroenterol. 2009 Jun 7;15(21):2628–2631.


2.   Lin HC et al. Small intestinal bacterial overgrowth: a framework for understanding irritable bowel syndrome. JAMA. 2004 Aug 18;292(7):852–858.


3.   Pyleris E et al. The prevalence of overgrowth by aerobic bacteria in the small intestine by small bowel culture: relationship with irritable bowel syndrome. Dig Dis Sci. 2012 May;57(5):1321–1329.


4.   Pimentel M et al. The effect of a nonabsorbed oral antibiotic (rifaximin) on the symptoms of the irritable bowel syndrome: a randomized trial. Ann Intern Med. 2006 Oct 17;145(8):557–563.


5.   Lauritano EC et al. Association between hypothyroidism and small intestinal bacterial overgrowth. J Clin Endocrinol Metab. 2007 Nov;92(11):4180–4184. 


6.   Almeida JA et al. Lactose malabsorption in the elderly: role of small intestinal bacterial overgrowth. Scand J Gastroenterol. 2008;43(2):146–154.


7.   Klaus J et al. Small intestinal bacterial overgrowth mimicking acute flare as a pitfall in patients with Crohn's Disease. BMC Gastroenterol. 2009 Jul 30;9:61.


8.   Marie I, Ducrotté P, Denis P, Menard JF, Levesque H. Small intestinal bacterial overgrowth in systemic sclerosis. Rheumatology (Oxford). 2009 Oct;48(10):1314–1319. Epub 2009 Aug 20.


9.   Rubio-Tapia A et al. Prevalence of small intestine bacterial overgrowth diagnosed by quantitative culture of intestinal aspirate in celiac disease. J Clin Gastroenterol. 2009 Feb;43(2):157–161.


10. Mancilla AC et al. [Small intestine bacterial overgrowth in patients with chronic pancreatitis].Rev Med Chil. 2008 Aug;136(8):976–980. 


11. Ojetti V et al. Small bowel bacterial overgrowth and type 1 diabetes. Eur Rev Med Pharmacol Sci. 2009 Nov–Dec;13(6):419–423.


12. Goebel A et al. Altered intestinal permeability in patients with primary fibromyalgia and in patients with complex regional pain syndrome. Rheumatology (Oxford). 2008 Aug;47(8):1223–1227. 


13. Gupta A et al. Role of small intestinal bacterial overgrowth and delayed gastrointestinal transit time in cirrhotic patients with minimal hepatic encephalopathy. J Hepatol. 2010 Nov;53(5):849–855.


14. Shanab AA et al. Small intestinal bacterial overgrowth in nonalcoholic steatohepatitis: association with toll-like receptor 4 expression and plasma levels of interleukin 8. Dig Dis Sci. 2011 May;56(5):1524–1534. 


15. Weinstock LB, Klutke CG, Lin HC. Small intestinal bacterial overgrowth in patients with interstitial cystitis and gastrointestinal symptoms. Dig Dis Sci. 2008 May;53(5):1246–1251. 


16. Weinstock LB, Walters AS, Restless legs syndrome is associated with irritable bowel syndrome and small intestinal bacterial overgrowth. Sleep Med. 2011 Jun;12(6):610–613. 


17. Parodi A et al. Small intestinal bacterial overgrowth in rosacea: clinical effectiveness of its eradication. Clin Gastroenterol Hepatol. 2008 Jul;6(7):759–764.


18. Husebye E. The patterns of small bowel motility: physiology and implications in organic disease and functional disorders. Neurogastroenterol Motil. 1999 Jun;11(3):141–161.


19. Bures J. 2010 Small intestinal bacterial overgrowth syndrome. World J Gastroenterol. 2010 Jun 28;16(24):2978–2990.


20. Pyleris E et al. The prevalence of overgrowth by aerobic bacteria in the small intestine by small bowel culture: relationship with irritable bowel syndrome. Dig Dis Sci. 2012 May;57(5):1321–1329.


21. Williams C et al. Occurrence and significance of gastric colonization during acid-inhibitory therapy. Best Pract Res Clin Gastroenterol. 2001 Jun;15(3):511–521.


22. Machado WM et al. The small bowel flora in individuals with cecoileal reflux. Arq Gastroenterol. 2008 Jul–Sep;45(3):212–218.


23. Khoshini R, Dai SC, Lezcano S, Pimentel M. A systematic review of diagnostic tests for small intestinal bacterial overgrowth. Dig Dis Sci. 2008 Jun;53(6):1443–1454.


24. Pimentel M. Gut microbes and irritable bowel syndrome [webcast]. July 20, 2012. GI Health Foundation. http://www.gihealthfoundation.org/coe/ibs/webcast/2012/july/MPimentel/?link=2012/
july/MPimentel&cme_proj_id=12&actionPage=topics/Gut_Microbes_and_
IBS/request-for-credit.cfm?cme_proj_id=12.

25. Bouhnik Y et al. Bacterial populations contaminating the upper gut in patients with small intestinal bacterial overgrowth syndrome. Am J Gastroenterol. 1999 May;94(5):1327–1331.

26. Youn YH, Park JS, Jahng JH, et al. Relationships among the lactulose breath test, intestinal gas volume, and gastrointestinal symptoms in patients with irritable bowel syndrome. Dig Dis Sci. 2011 Jul;56(7):2059–2066. Epub 2011 Jan 15.


27. Elsenbruch S. Abdominal pain in irritable bowel syndrome: a review of putative psychological, neural and neuro-immune mechanisms. Brain Behav Immun. 2011 Mar;25(3):386–394. Epub 2010 Nov 20.


28. Pimentel M. A New IBS Solution. Sherman Oaks, CA: Health Point Press; 2006.


29. Pimentel M, Mayer AG, Park S, Chow EJ, Hasan A, Kong Y. Methane production during lactulose breath test is associated with gastrointestinal disease presentation. Dig Dis Sci. 2003 Jan;48(1):86–92.


30. Kunkel D et al. Methane on breath testing is associated with constipation: a systematic review and meta-analysis. Dig Dis Sci. 2011 Jun;56(6):1612–1618.

 
31. Pimentel M, Lin HC, Enayati P, et al. Methane, a gas produced by enteric bacteria, slows intestinal transit and augments small intestinal contractile activity. Am J Physiol Gastrointest Liver Physiol. 2006 Jun;290(6):G1089–G1095. Epub 2005 Nov 17.


32. Chatterjee S et al. The degree of breath methane production in IBS correlates with the severity of constipation. Am J Gastroenterol. 2007 Apr;102(4):837–841.


33. Singh VV, Toskes PP. Small bowel bacterial overgrowth: presentation, diagnosis, and treatment.Curr Treat Options Gastroenterol. 2004 Feb;7(1):19–28.

34. DiBaise JK. Nutritional consequences of small intestinal bacterial overgrowth. Prac Gastroenterol. 2008;69:15–28. 


35. Prizont R. Glycoprotein degradation in the blind loop syndrome: identification of glycosidases in jejunal contents. J Clin Invest. 1981 Feb;67(2):336–344.


37. Lauritano EC, Valenza V, Sparano L, et al. Small intestinal bacterial overgrowth and intestinal permeability. Scand J Gastroenterol. 2010 Sep;45(9):1131–1132.


36. Resnick C. Nutritional protocol for the treatment of intestinal permeability defects and related conditions. Nat Med J. March 2010.

38. Bowman, G. The Gut, the Brain and the Functional GI Disorders. Functional Gastroenterology Seminar: Level 1. Winter 2010, p. 19. 

39. Gabrielli M, Lauritano EC, Scarpellini E, Lupascu A, Ojetti V, Gasbarrini G, Silveri NG, Gasbarrini A. Bacillus clausii as a treatment of small intestinal bacterial overgrowth. Am J Gastroenterol. 2009 May;104(5):1327–8. Epub 2009 Apr 7.


40. Soifer LO, Peralta D, Dima G, Besasso H. 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 Gastroenterol Latinoam. 2010 Dec;40(4):323–7.


41. Schiffrin EJ, Parlesak A, Bode C, Bode JC, van't Hof MA, Grathwohl D, Guigoz Y. Probiotic yogurt in the elderly with intestinal bacterial overgrowth: endotoxaemia and innate immune functions. Br J Nutr. 2009 Apr;101(7):961–6.

42. Gottschall E. Breaking the Vicious Cycle. Baltimore, ON: Kirkton Press Ltd.; 1994.


43. Campbell-McBride N. Gut and Psychology Syndrome. Cambridge: Medinform Publishing; 2004.
44. Ong DK, Mitchell SB, Barrett JS, et al. Manipulation of dietary short chain carbohydrates alters the pattern of gas production and genesis of symptoms in irritable bowel syndrome. J Gastroenterol Hepatol. 2010 Aug;25(8):1366–1373.


45. Nieves R, Jackson RT. Specific carbohydrate diet in treatment of inflammatory bowel disease.Tenn Med. 2004 Sep;97(9):407.