# Is IBS caused by bacterial gas? Is testing worthwhile?



## tummyrumbles (Aug 14, 2005)

IBS is characterised by carbohydrate malabsorption and gas.

IBS-constipation patients are believed to be predominantly methane producing whereas IBS-diarrhea patients are hydrogen producing. Both methane and hydrogen are considered possible neurotransmitters and both can affect gut motility. Gas can therefore affect bowel evacuation.

Studies have shown that Methane slows intestinal transit however it is also suggested that methane also triggers non-propulsive or segmental contractions - i.e. hyperperistalsis or hypermotility, and that this may be responsible for the slowing of overall gut transit.

http://ajpgi.physiology.org/content/290/6/G1089

Hydrogen doesn't cause osmotic diarrhea (which is due to malabsorbed carbohydrates and their by-products) however is believed to cause gas, cramping and hypermotility.

Unclear Abdominal Discomfort: Pivotal Role of Carbohydrate Malabsorption

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC4015196/

FODMAPs can induce symptoms of both diarrhea and constipation. The low FODMAP diet is recommended for all IBS patients. FODMAPs may have a laxative effect on some people and a constipating effect on others.

Evidence-based dietary management of functional gastrointestinal symptoms: The FODMAP approach

http://onlinelibrary.wiley.com/doi/10.1111/j.1440-1746.2009.06149.x/full

Fibre, FODMAPs and resistant starch can exacerbate flatulence, constipation and diarrhea for all IBS types.

SIBO testing:

SIBO describes the overgrowth of bacteria in the small intestine. There are suggestions that SIBO underlies IBS however the testing is controversial.

Use and Abuse of Hydrogen breath tests

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC1856094/

This study suggests that SIBO testing has several drawbacks.

The hydrogen breath test alone won't identify methane. There can be false positives due to gastrointestinal motor disorders, delayed gastric emptying and rapid transit through the small bowel. False positives can also occur due to oral bacteria and if the patient failed to adhere to a low fibre diet the previous day. Smoking can also affect the results of the test.

Glucose testing can also result in a false positive in the case of slow intestinal transit.

The author believes that interpretation can be skewed. It is claimed that a positive lactulose test and antibiotics proves the presence of SIBO, however an alternative view is that the positive breath test is due to colonic bacteria.

This study suggests that all current tests are flawed.

Is the &#8230; methane breath test an accurate diagnostic tool for SIBO?

http://gut.bmj.com/content/61/Suppl_2/A248.3.abstract

Is SIBO or dysbiosis testing necessary for IBS? There is no evidence that antibiotics will cure the condition long-term and most SIBO patients relapse under this treatment. A low carbohydrate diet is recommended in both cases and may be a better long-term plan.

A long period of overnight fasting will help. Keeping to 3 meals a day (no grazing) will also help. The migrating motor complex is a fasting, interdigestive process that sweeps bacteria from the small intestine. Many people find that simply eating dinner early and ensuring a long, overnight fast aids a more efficient bowel evacuation the next morning.

Mechanism of Interdigestive Migrating Motor Complex

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3400812/


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