SIBO – IBS Researcher

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Table of Contents
What Is SIBO?
Causes Of SIBO
How Common Is SIBO?
SIBO Diagnosis
– Jejunal-Aspiration
– SIBO Breath Test
– Medication Trial
– Probiotics
SIBO Treatment
When To Consider SIBO
Further Reading And References

What Is SIBO?

Small intestine bacterial overgrowth (SIBO) relates to an excessive amount of bacteria in the small intestine. Although an entirely different condition to IBS, symptoms are very similar to IBS including abdominal pain, particularly after eating, bloating, cramps, diarrhoea, constipation, indigestion, gas and a feeling of fullness. (1)

Causes Of SIBO

The small intestine normally harbours lower bacterial content than the oral cavity and the colon. This suppression of bacteria in the small intestine is facilitated by physical and chemical barriers. The presence of an overgrowth of bacteria in the small intestine suggests a loss of these barriers. These include gastric acid, produced by the pancreas and liver to aid digestion of foods, the movements of the small intestine that occur every 90 to 120 minutes in waves during fasting, intestinal barrier integrity, the gut microbiota, and ileocecal valve, which is a barrier at the end of the small intestine that prevents faecal matter or microbiota returning from the colon to the small intestine. (8)

It is only possible to have SIBO if you have one of its root causes. Focus should initially be on treating the cause of SIBO, then tackling the overgrowth of bacteria, otherwise it will keep coming back. Note that the first four causes of SIBO in the list below should be identifiable through a small bowel MRI scan:

Stasis: dysmotility – problems with muscle contraction in the gastrointestinal tract
Surgery (loops, vagotomy, bariatric)
Short Bowel Syndrome
Stuck open ileocecal valve (which sits between the small and large intestine) allowing bacteria from the large intestine to flow back into the small intestine
Achlorhydria – no stomach acid – unlikely if you can experience acid reflux. Additionally a faecal elastase test would show if you aren’t breaking down proteins correctly (which require stomach acid for digestion)
Hypochlohydria – low stomach acid – see above – the only real test is a PH test directly into your stomach, but many practices do not carry this out and home testing is inaccurate
PPIs – proton pump inhibitors for GERD/acid reflux – this is particularly related to long term use
Malnutrition – excess bacteria in the small intestine can compete for nutrients that your body needs
Collagen vascular disease – immune system inflammation e.g. arthritis
Immune deficiency
Advancing Age
Chronic Pancreatitis – this causes constant abdominal pain/fatty stools
Chronic antibiotic use
IgA Deficiency – identified from GP blood tests
Coeliac Disease – identified from GP blood tests
Crohn’s Disease – identified through GP tests and colonoscopy if GP tests indicate referral is needed
NASH – non alcoholic fatty liver disease –identified from GP blood tests
Cirrhosis
Fibromyalgia – widespread pain
Rosacea

(2)

How Common Is SIBO?

There is no clear statistic about how many people in the population are diagnosed with and treated for SIBO (3). My gastroenterologist stated that true SIBO cases are rare. Others state that it is very common – many of these, though, are private practitioners who are making vast sums of money by claiming that they can diagnose and treat it.

SIBO Diagnosis

Jejunal Aspiration

Jejunal Aspiration is the most accurate test for SIBO. This is carried out during endoscopy procedure, where a long tube with a camera is thread down the throat, into the stomach and on to the middle section of the small intestine (jejunum) where a sample is taken. The sample is cultured and evaluated for bacteria.

Although the most accurate test it can have some drawbacks:

Very rarely used, due to invasive nature, time and cost and more risky than other tests though considered safe
Possibility of false negatives from:
- bacteria not overgrown in the location where the sample is taken
- incorrect culture for the bacterial strain present in the sample
- sample compromised by bacteria on the implement due to poor handling or from bacteria in the mouth

(4)

SIBO Breath Test

A SIBO breath test is the most common method used for diagnosis. It involves consuming a sugary drink and collecting samples of your breath at intervals up to 90 minutes. The samples are tested for hydrogen or methane. Hydrogen is produced by bacteria and methane by organisms called archaea in the large intestine and not the small intestine. Finding hydrogen and/or methane suggests misplaced bacteria and/or archaea in the small intestine. The cut off is 90 minutes since it can take up to 2 hours for the sugar solution to reach the large intestine. Hydrogen dominant SIBO tends to be associated with diarrhoea, whilst methane dominant is associated with constipation (5).

However, breath tests are not particularly accurate since:

the sensitivity (accurately diagnosing those with SIBO) and specificity (accurately diagnosing those without SIBO) of the tests range from 44% to 83% indicating that the tests are not reliable
they can produce many false positive results, particularly in those who digest food faster than average
the tests can produce false negatives, often due to gastroparesis (slow emptying of the stomach)
lack of consensus on how to perform the tests
lack of agreement concerning what amount of gas should determine a positive diagnosis

(4)

There is a device called Foodmarble that has a breath analyser, which is similar to the BreathTracker device used for SIBO breath testing (10), but with the addition of FODMAP testing and symptom tracking and other features. However, it would be expected that this device would suffer similar issues to those problems mentioned above. Additionally, FODMAP elimination and reintroduction involves tracking your own reactions to foods in response to consuming specific FODMAPs, so it is unclear what additional benefit would be gained from knowing the amount of gas produced, when you can already feel this from symptoms.

Medication Trial

Trialling medication that is aimed at SIBO, to find out whether it causes a rapid drop off in symptoms. If it does, this suggests a SIBO diagnosis. (4)

Probiotics

Some studies have shown that taking probiotics when you have SIBO can make SIBO symptoms worse (6). This may be due to adding bacteria from probiotics on top of too much bacteria in the small intestine. If you take probiotics and your symptoms get worse and worse over time, whilst allowing enough time for your body to get used to them, this may be an indicator that you have SIBO, but this is only a theory. Similarly, if probiotics make your symptoms better (after a bedding in period), theoretically you may be more likely to have IBS than SIBO.

SIBO Treatment

The most common medication for SIBO is an antibiotic drug called Xifaxan (rifaximin), taken for a two week period, then repeating for another one to two weeks. This antibiotic acts directly on bacteria in the small intestine, rather than being absorbed into the blood stream (4). Rifaximin works best for hydrogen dominant SIBO. Neomycin (another antibiotic), or a combination of rifaximin and neomycin may be better for those with methane dominant SIBO. However research into SIBO treatments is ongoing. (5)

Recurrence rates are extremely high so tackling the underlying cause of SIBO is very important. (5)

There are many nutritional therapists who are diagnosing SIBO and claim that they can treat SIBO. Nutritional Therapy is a practice that is not recognised by the NHS in the UK (7). The Nutritional Therapy courses are run by private bodies and some of the courses have very little in the way of prerequisites to join them, yet the therapists are using medical diagnostic tests, some not verified by proper clinical trials and require a degree in microbiology to interpret them. Unfortunately, these practitioners are over diagnosing people with SIBO. Every one that I spoke to suggested that I had it. I went ahead with the breath testing which came back with a false positive for both hydrogen and methane. I know it was a false positive since none of the treatments worked, including Rifaximin and Neomycin, which I had to obtain via a private prescription. Conveniently they told me how difficult it was to treat, but if I try this or that extortionately priced product, that will cure it, whilst they were also picking up exorbitant fees from me in the process. They took me through a highly restrictive dietary regime either through liquid diets or high protein, low carbohydrate diets which removes feed for the microbiome and increases inflammation in the body. My calprotectin inflammation marker prior to their ‘treatments’ was normal. After their highly restrictive diets, antibiotics and taking natural antimicrobials for an extended period of time, effectively destroying my microbiome, I lost more than a stone in weight (that I could not afford to lose), my calprotectin, inflammation marker, was sky high, to the point my NHS gastroenterologist assumed that I had inflammatory bowel disease and sent me for a colonoscopy. Fortunately, I obtained a different diagnosis and treatment through the NHS.

The use of nutritional therapists to diagnose and treat SIBO should be avoided.

During an interview with Jonathan Wolf of the Zoe personalised nutrition programme, Dr. Will Bulsiewicz, a gastroenterologist and author, suggests that those with SIBO go on a low FODMAP diet initially to reduce gas production from the overgrowth of bacteria in the small intestine. They mention a study found a 29% drop in hydrogen from bacteria after 2 weeks of being on the low FODMAP diet. Gas production was dropped even further to 41% by taking Saccharomyces boulardii in addition to the diet. Saccharomyces boulardii is a beneficial fungus and not a bacteria, so won’t add to the bacteria in the small intestine. The low FODMAP diet is not forever and FODMAPs will need to be gradually reintroduced. Dr. Bulsiewicz also mentions that it is a myth that natural antimicrobial supplements are safer than antibiotics. This is not true since both kill bacteria and supplements are not regulated. There will also be less research into efficacy of and risks associated with these supplements. In summary, he recommends treating with antibiotics, but not dropping fibre since this can adversely impact health. However, going low FODMAP initially, but then ramping up the FODMAPs over time for health reasons and effectively rebuilding the microbiome after any antibiotics. He absolutely does not recommend destroying the microbiome in order to treat SIBO. (9)

When To Consider SIBO

Discuss the possibility of SIBO with your GP or gastroenterologist only, if:

you have one of the causes of SIBO, and/or
a three month trial of a good probiotic like Alflorex gradually make your IBS symptoms much much worse