SIBO Testing UK

The SIBO test measures the levels of hydrogen and methane gas in the breath. The presence of these gases in the breath can indicate an overgrowth of bacteria in the small intestine.

IBS Specialists as featured in the Guardian

OCTOBER 2023

SIBO TESTING UK

IBS specialist consulting with a young couple

How do you conduct SIBO testing for Small Intestinal Bacterial Overgrowth?

The test for SIBO has a number of names including:

Hydrogen Breath Test

Hydrogen and Methane Breath Test

Lactulose or Glucose Breath Test

The breath test is often used for patients who have symptoms of IBS such as diarrhoea pain, cramping, bloating, gas or nausea. We can post tests all over the UK and Europe.

What does the test for Hydrogen measure?

The SIBO test measures the levels of hydrogen and methane gas in the breath. The presence of these gases in the breath can indicate an overgrowth of bacteria in the small intestine. The large intestine contains large amounts of bacteria. In some cases these strains of bacteria can migrate to the small intestine causing gas due to the fermentation of carbohydrates.

If Hydrogen and Methane are produced they will diffuse into the blood, and then into the lungs, for expiration.

What is the difference between the Lactulose and Glucose Breath test when testing for SIBO?

 

The lactulose breath test has the advantage that the lactulose is able to travel throughout the entire small intestine. This is important as you will be able to detect if there is bacteria is present in the ileum (the final section of the small intestine) where small intestinal bacterial overgrowth often occurs. However for some people, the speed at which food move through their intestines can be very rapid, causing lactulose to reach the colon too quickly. This can sometimes result in a false positive result.

A false positive result may occur if you have frequent diarrhea or know that you tend to experience a faster transit time. Lactulose can have a laxative effect on the body and can indeed increase transit time and help with constipation. This may be why some people feel better after the completing the test.

 

 

Should I use a Glucose Breath test instead?

The problem with the glucose breath test is that it is unable to identify the growth of bacteria it in the last section of your small intestine. This means the test may produce a false negative result.

 

 

If my results have a flat-line could this still mean I have a bacterial overgrowth?

There is a still a lot of research to be done but it appears that for some patients there is a third gas called Hydrogen Sulfide that may be linked to small intestinal bacterial overgrowth. This test should be available in the UK shortly.

 

 

Does the Breath test include Hydrogen Sulfide?

There is another gas called Hydrogen Sulfide that may also be linked with Small Intestinal Bacterial Overgrowth.

Hydrogen sulfide is recognized by its distinct rotten egg odor, unlike hydrogen and methane, which are odorless. While humans produce only small amounts of this gas, certain bacteria can generate excessive hydrogen sulfide. This overproduction is linked to symptoms such as diarrhea, abdominal pain, and rectal urgency, stemming from an imbalance in sulfate-reducing organisms that produce hydrogen sulfide.

If you have many of the symptoms of SIBO such as wind, flatulence or bloating or you have noticed an unpleasant smell similar to sulphur then hydrogen sulfide overgrowth might be an issue. We recommend herbal antibiotics  and eating low-sulphur foods  to help you. Some patients who experience body pain, diarrhoea, constipation, bladder irritation, tingling and numbness in their extremities, as well as sulphur smelling gas may have indeed have Hydrogen Sulfide overgrowth.

Chalk board with SIBO written on it

What is the cost of a Hydrogen breath test?

The cost of a test for SIBO is £165.

Can the Hydrogen Breath test be conducted at Home?

The Hydrogen test kit can easily be conducted at home, we ship all over the UK.

We also have a clinic in Harley Street in central London. One of our team can also make home visits if you prefer.

What happens when my results are ready?

The results take approximately five days and as soon as they are ready we will e-mail them to you.

SIBO specialist sitting with her patient

Do you have SIBO Specialists?

Once your results are back, our SIBO specialists that will discuss your individual treatment plan. You will receive tailored recommendations based on any predisposing factors that may be contributing to the condition. This will include herbal treatment and dietary changes.

How is the SIBO Breath Test carried out?

The first step involves following a low-fibre diet for at least one day and fasting for 14 hours overnight. You will then need to drink a solution called Lactulose or Glucose. This is a very sweet solution that tastes like sugar. Breath samples are taken at 20 minute intervals for the period of 3 hours. The SIBO breath test is very easy to complete. If you do this test at home we will send you a you tube video to follow step-by-step.

Who should conduct a TEST for SIBO?

Research indicates that SIBO and IBS share a number of common symptoms including bloating, diarrhoea, wind and pain (Source PubMed)

Moreover in 2020 (Source PubMed), a study indicated that 62.3 % of patients who conducted a lactulose breath test had previously been diagnosed with IBS.

About 35.5% of IBS-D cases are associated with SIBO. On the other hand, when IBS is primarily characterized by constipation (IBS-C) or a mix of symptoms (IBS-M), the connection with SIBO is lower, at 22.5% and 25.2%, respectively.

Here’s the catch: The NHS, as of now, doesn’t routinely test for SIBO. However, if you’ve received an IBS diagnosis, it’s a crucial step to consider. Understanding the potential SIBO link to IBS may be the key to improving your digestive health.

In my clinical experience, at least 40% of patients who have IBS and have taken the SIBO test do test positive for SIBO.

What is SIBO?

Small intestinal bacterial overgrowth (SIBO) is a painful condition of the gut caused by the presence of excessive numbers of bacteria in the small intestine. The small intestine is where most of the digestion and absorption of food and nutrients happens. Unlike the colon which is part of the large intestine and proliferates with bacteria, the small intestine is normally sparsely populated by bacteria. Bacterial overgrowth can happen when bacteria move from the large intestine to the small intestine or when naturally occurring bacteria in the small intestine grow out of control.

In a healthy individual, the body will try and remove large concentrations of bacteria from the small intestine using a migrating motor complex, MMC to sweep out the bacteria. SIBO can develop when the normal control mechanisms that keep the growth of bacteria in check are disrupted.

Causes of SIBO

A common cause of SIBO may be due to the production of low levels of stomach acid. If you have experienced chronic or acute stress, for prolonged periods of time, you may not have produced adequate amounts of hydrochloric acid as needed.

The medical term is known as Achlorhydria (lack of Hydrochloric acid). If you had an Helicobacter pylori infection yoy may be at risk of low stomach acid Source Pubmed. In a healthy person production of HCl (stomach acid) may help eradicate any incoming bacteria. 

For some people SIBO can develop after use of medications that reduce stomach acid production. These include proton pump inhibitors such as Omeprazole, Lansoprazole. Source PubMed. The over-use of these medications may cause bacterial overgrowth in the duodenum and stomach. Proton pump inhibitors may also accelerate the intestinal transit causing diarrhoea. Source PubMed

Another cause may be due to food poisoning- If you have had Campylobacter or Acute Gastroenteritis this may affect or damage the MMC – motor migrating complex. The MMC is a little bit like a wave or a broom stick that clears out bacteria into the large intestine. If it is not working properly you are more likely to have an overgrowth of bacteria. Research indicates that the malfunctioning of the MMC may be occur post food poisoning.

  • Pancreatic exocrine insufficiency, (lack of pancreatic enzymes). If you are not producing adequate amounts of enzymes to break down your food, this deficiency may lead to a bacterial overgrowth
  • There are many medical conditions that have been linked with SIBO. These include gastroparesis (delayed stomach emptying), irritable bowel syndrome, Crohn’s disease, coeliac disease and small bowel dysmotility. Motility is a big issue for patients with SIBO- either too fast or too slow
  • Other conditions include people with a suppressed immune system
  • Decrease in Bile acids – this is because bile acids may prevent the growth of bacteria
  • Stress because it reduces the motility of the intestine potentially causing an overgrowth
  • Problems with your IIleocecal Valve-the latter prevents a backflow of bacteria from large intestine to small intestine
  • There may be some adhesions or strictures that have formed after surgery that cause the bacterial overgrowth. This may happen with patients who have Appendicitis, Endometriosis, Cancer, or inflammatory bowel disease.

Symptoms of SIBO

The signs and symptoms of SIBO are non-specific and are similar to other digestive disorders such as irritable bowel syndrome (IBS), lactose intolerance and fructose malabsorption. Common complaints include:

  • Abdominal pain and discomfort
  • Bloating
  • Indigestion
  • Diarrhoea
  • Constipation
  • Unintentional weight loss
  • Inability to tolerate high fibre foods including vegetables, broccoli, beans, lentils, onions and garlic
  • Belching
  • Excessive gas and flatulence
  • Anxiety or brain fog
  • Malabsorption, Anemia-  (Iron, B12, Ferritin deficiency)
  • Leaky gut leading to joint pain, or body pain rashes on skin and severe food intolerances
  • Rosacea

Does the NHS test for SIBO?

The answer is Yes and No. SIBO is becoming more mainstream, however the NHS still does not routinely pinpoint SIBO symptoms. If you are offered SIBO testing it will be via a gastroenterologist and there may be long waiting times on the NHS.

The majority of SIBO diagnostics conducted on the NHS tends to use glucose as the sugar solution. This may be problematic and produce false negatives. Glucose is usually absorbed within the upper portion of the small intestine (only the top two feet ) so if hydrogen and/or methane are detected in this test it indicates an overgrowth in upper end of the small intestine, closest to the stomach.

The problem with the glucose breath test is that is unable to identify the growth of bacteria it in the last section or distal end of your small intestine. This means the test may produce a false negative result.

Because of the large amount of symptom overlap of SIBO with other gastrointestinal conditions like IBS, it is important that proper testing is done to ensure a correct diagnosis and treatment. If symptoms point to SIBO, then a breath test is usually requested.

 

Do you have questions or would to see how we can assist you?

Are there any other tests that be conducted to test for SIBO?

The gold standard to detect small intestinal bacterial overgrowth is an invasive test whereby an endoscope is used to collect a fluid sample from your small intestine. This fluid is then tested in a laboratory.

SIBO Treatment & Eradication

How is Small Intestinal Bacterial Overgrowth Treated?

Typically herbal antibacterials and antibiotics are used for the treatment of small intestinal bacterial overgrowth as well as a low-Fodmap diet. However we have found that the low-Fodmap diet does not work for many patients and have devised a low-fermentable low sugar diet that may be of greater benefit.

What is your approach to eradicating SIBO?

The first step is understanding the specific causes of the bacterial overgrowth as they are different for every individual.

For example did you have food poisoning or gastroenteritis before your symptoms started? Were you in a car crash? Do you also have a fungal overgrowth? Is the Ileocecal valve the cause the bacterial overgrowth?

Do you also have food intolerances? Do you have Histamine issues? Do you have intestinal permeability /leaky gut? Have you had surgery? Are proton pump inhibitors such as Omeprazole, Lanzoprazole part of the puzzle? Is upper and lower motility the cause of your SIBO? Have you been under acute stress?

All of the these factors need to be taken into consideration and will be explored in detail before making any recommendations.

We have found that speaking to a professional will greatly improve patient outcome.

Sometimes we recommend blood testing to to assess malabsorption and vitamin and mineral deficiencies and stool tests to assess fat malabsorption.

We never use a blanket protocol, we offer a tailored solution to every patient. During the initial consultation, we will listen carefully to your specific set of symptoms and medical history before devising a tailored treatment plan. If you have already conducted a SIBO test or other tests we will certainly review those as well.

SIBO Natural Treatment

The treatment of Small Intestinal Bacterial Overgrowth (SIBO) can be managed through both herbal treatments and antibiotics.

Our clinical approach is based on using herbal treatments, prokinetics and dietary modifications.

The key to successful treatment is try to understand each person’s individual causes for SIBO and tailoring a plan that is suited to their medical history.

For both types of SIBO, Hydrogen dominant and Methane dominant we use herbal antimicrobials, these are natural treatments and include supplements such as Atrantil, Allicin, Oregano and Berberine. The key is to select the appropriate dose and supplements based on the patients medical history.

Can I get Rifaximin from my GP?

Obtaining Rifaximin through your general practitioner (GP) can often be a challenging process. It typically necessitates a referral to a

Gastroenterologist, which may result in considerable waiting times and associated expenses. In addition to the cost of a private

Gastroenterologist consultation, you will be required to cover the expenses associated with antibiotics. Using herbal antibiotics may be a much faster route and offer an economical alternative.

Antibiotics may have side effects such as gastrointestinal upset, allergic reactions, and disruptions to the natural gut microbiome. Herbal treatments, when used appropriately, are often associated with fewer and milder side effects.

Unfortunately side-effects can also occur with herbal antibiotics if the dosage is too high or if they are mixed inappropriately. Moreoever there can be interactions with medications. We have also found that the quality of supplements found on the high street is variable so would recommend booking in a consultation with our SIBO specialists.

Less damage to the Gut Microbiome

Unlike antibiotics, certain herbs like berberine and oregano oil are less likely to harm your gut’s healthy bacteria. This means they have a milder impact on your overall gut health.

Long-Term Management of SIBO

Herbal treatments may be more suitable for individuals who require long-term management of SIBO, as antibiotics are typically used for shorter durations due to concerns about antibiotic resistance and the gut microbiome.

Combination Therapy

In some cases, a combination of herbal and antibiotic treatments may be considered for SIBO, as this can capitalize on the benefits of both approaches.

The choice between herbal an antibiotic treatments may also depend on an individual’s overall health including any pre-existing conditions or allergies.

What about antibiotics?

Antibiotics such as Rifaximin are used to treat Small Intestinal Bacterial Overgrowth. However there are two key issues:

  1. They may have significant side-effects
  2. They are fairly difficult to get hold of in the UK as GPs do not routinely prescribe them. Patients will typically need to find a Gastroenterologist that specialises in SIBO.
  3. They are very expensive

The good news is that research indicates that the efficacy of herbal antibiotics is equivalent to Rifaximin for the treatment of Small Intestinal Bacterial Overgrowth. Clinically this is what we have witnessed.

Herbal antibiotics are readily available and can be bought over the counter from professional supplement shops. Below is a list of the most effective SIBO supplements that we frequently use in our clinic.

Herbal Antibiotics

Oregano Oil: Oregano oil contains compounds like carvacrol and thymol, which have antimicrobial properties that can help reduce bacterial overgrowth.

Berberine: Berberine, found in herbs like goldenseal and Oregon grape, has been shown to inhibit the growth of pathogenic bacteria in the gut.

Neem: Neem, a tree native to India, has antibacterial properties and may help control SIBO.

Peppermint Oil: Peppermint oil can relax the muscles of the small intestine and alleviate symptoms like bloating and abdominal pain.

Allicin: Allicin and Allimed are often used for Methane dominant SIBO and may help with reducing archaea. This supplement is based from Garlic; however the fermentable element has been removed and even if garlic is a high-fodmap foods, many people can tolerate it.

Atrantil: Atrantil is very effective for wind and bloating. There can be interactions with medications such as blood thinners, anti-depressants.

What supplements are best for Hydrogen Sulfide SIBO?

Typically we find Oregano oil to be of the greatest benefit.

Biofilm Disruptors

Biofilm disruptors such as Lactoferrin and NAC have also been of benefit. Biofilms are groups of microorganisms such as bacteria and fungus, that are protected by a layer slime. This makes antimicrobia and antibiotic therapy very difficult. However using a biofilm disruptor can help infiltrate these organisms and then clear out the leftover matrix, minerals, and bacterial DNA of the organisms.

Candida and SIBO can co-exist- SIFO AND SIBO

In some cases candida and yeast infections may co-exist, (Small Intestinal Fungal Overgrowth) and it will be important to address both by taking anti-fungals as well. Grapefruit Seed, Caprylic acid have often helped enormously. a very common comorbidity for SIBO sufferers, affecting around half of SIBO cases (5).

How long will it take to treat SIBO?

The duration of treatment will vary greatly from each individual. On average 4-8 weeks is needed. Some patients respond after just 3-4 weeks, other may need 3 rounds of anti-microbials. Sometimes you will find that your SIBO symptoms disappear and then slowly return after three months. We also recommend taking some prokinetics, possibly some hydrochloric acid if needed or bitters.

Is there a cure for SIBO?

In many cases, SIBO can be successfully treated by directly addressing the bacterial overgrowth. The most common first-line antibiotic prescribed is Rifaximin. The problem with antibiotics is that they are not always initially effective with one study finding that in people with SIBO-related IBS, two-thirds had to be retreated with Rifaximin, with some needing re-treatment up to 5 times. This raises the very serious concern of developing bacterial antibiotic resistance.

We have successfully used herbal treatments such as oil of oregano, lemon balm, and red thyme oil, we have found these to be an effective alternative treatment for SIBO. A 2014 study found that herbal treatments were just as effective as the antibiotic Rifaximin in treating SIBO. And from the same study, herbal treatments were just as effective as triple antibiotic therapy in people that did not respond to rifaximin.

What types of Dietary modifications do you recommend?

One of the key components of managing SIBO naturally is adjusting your diet. The goal is to reduce foods that encourage bacterial overgrowth while promoting a balanced gut microbiome.

Some of the diets that we may use include the Low FODMAP Diet: Fermentable oligosaccharides,disaccharides, monosaccharides, and polyols. (FODMAPs) are types of carbohydrates that can exacerbate SIBO symptoms. A low FODMAP diet restricts these compounds and may help alleviate symptoms. This is quite a complex diet and we will simplify it to make it much easier for you to follow and ensure it is taiored for SIBO patients.

Elemental Diet: An elemental diet involves consuming pre-digested nutrients in liquid form, which may give the gut a break from bacterial fermentation and promote healing.

What types of bacteria are present in small intestinal bacterial overgrowth?

According to Dr Pimentel, there are a specific strains of bacteria including Klesbiella Escherichia coli and Enterococcus that may be detected in patients with small intestinal bacterial overgrowth. These are likely linked to IBS-D and Hydrogen dominant SIBO. Unfortunately Klebsiella species, may produce toxins that damage the mucosa. This may lead to malabsorption.

Certain types of bacteria can cause malabsorption in SIBO

Research indicates that fat malabsorption or bile acid diarrhea may be linked to a predominance of bacteria that metabolize bile salts to unconjugated or insoluble compounds.

Certain types of bacteria can cause bloating without diarrhea in SIBO

It appears that some patients who experience bloating without diarrhea have an abundance of microorganisms that metabolize carbohydrates to short-chain fatty acids and gas.

Is there a link Between SIBO and IBS?

Is there a link between Irritable Bowel Syndrome and SIBO?

The causes of irritable bowel syndrome are still unknown. However without a doubt, symptoms of SIBO and IBS are very similar. earlier, SIBO is frequently found in 30-85% of patients fulfilling criteria of irritable bowel syndrome (30%-85%)[9-11,14,15,]. Dr Pimental believes that SIBO is the primary cause of irritable bowel syndrome.

What is the link between and intestinal methanogen overgrowth and SIBO with constipation?

However if you suffer with IBS-C, Irritable bowel syndrome with constipation, this may be due to an organism named Methanobrevibacter smithii. This is classified as an archaeon and actually overgrows outside of the small intestine and is referred to as intestinal methanogen overgrowth.

Is there a link with Coeliac disease and SIBO?

A wide range of 9% to 55% (10) of patients have been diagnosed with SIBO as a complication of coeliac disease. If you are not responding to a gluten-free diet you may wish to test for SIBO.

Is there a link with Chrons disease and SIBO?

SIBO is found in about 25% of patients with Crohn’s disease (11,12) . In fact the symptoms of SIBO are very similar to Crohn’s disease ( increased bowel movements and lower body weight).

Is there a link between malabsorption and SIBO?

We often also recommend that a vitamin and mineral blood test is conducted to detect any nutrient deficiencies such as B12, folate and iron deficiencies. In some cases we also recommend a stool evaluation to test for fat malabsorption.

Prokinetics

These can also very important as well when treating SIBO. The term prokinetic means simply to promote movement and, in the context of the gastrointestinal tract. These are not be confused with laxatives. A prokinetic is useful to stimulate the MMC complex- motor migrating complex and is best taken at bed before fasting and help clear bacteria out of the small intestine.

Some examples include:

  • Ginger root and ginger formulas (1000 mg )
  • Motility activator-This is less likely to cause side-effects with patients who have acid reflux.
  • Pure encapsulations-MotilPro
  • Bio-Mi Kinetic

The Importance of Diet and SIBO

Dietary changes are also an important part of managing SIBO. Because bacteria feed on carbohydrates, then a diet that aims to reduce these can help. A low FODMAP diet is sometimes recommended to treat SIBO and which also has proven effective in treating IBS. FODMAPs are short-chain carbohydrates such as lactose, fructose, fructans (long chains of fructose molecules) and sugar alcohols that are commonly present in dairy products, grains, legumes and certain fruits and vegetables. The reduction in fermentable carbohydrates in the diet helps to starve excess bacteria of their important food source.

Following the low FODMAP diet for extended periods of time may lead to a reduction of healthy gut bacteria know as Bifidobacteria. Therefore it is important after treatment SIBO and following a low-fodmap diet to take probiotics to replenish the concentration of healthy gut bacteria (7). The low FODMAP may also results in calcium deficiency.

The elemental diet is another option for people with SIBO. The diet supplies nutrients in an easy-to-digest form. The easier and quicker digestion and absorption of nutrients mean there is less available for bacteria to feed off. In a 2-week study of people with SIBO-related IBS trialling an elemental diet, 80 percent returned a normal lactulose breath test after 1 month.

With SIBO, different dietary changes work for different people. That is where working with an experienced nutritionist to assist in tailoring changes to your diet to manage symptoms of SIBO can be of help.

The SIBO breath test (Small Intestinal Bacterial Overgrowth) is also an excellent test that is now available and is also of tremendous benefit to IBS sufferers.

 

Do you have questions or would to see how we can assist you?

References

1. Clin Gastroenterol Hepatol. – Breath testing for small intestinal bacterial overgrowth: maximizing test accuracy.

2. Wur J Gastroenterol Hepatol. – Breath tests in the diagnosis of small intestinal bacterial overgrowth in patients with irritable bowel syndrome in comparison with quantitative upper gut aspirate culture.

3. Gut Liver. – Small Intestinal Bacterial Overgrowth and Irritable Bowel Syndrome: A Bridge between Functional Organic Dichotomy.

4. Dig Dis Sci. – Comparison of scintigraphy and lactulose breath hydrogen test for assessment of orocecal transit: lactulose accelerates small bowel transit.

US National Library of Medicine – Small Intestinal Bacterial Overgrowth: A Comprehensive Review.

US National Library of Medicine – How to Interpret Hydrogen Breath Tests.

Springer Link – Effects of Rifaximin Treatment and Retreatment in Nonconstipated IBS Subjects.

US National Library of Medicine – Herbal Therapy Is Equivalent to Rifaximin for the Treatment of Small Intestinal Bacterial Overgrowth.

US National Library of Medicine – Efficacy of the low FODMAP diet for treating irritable bowel syndrome: the evidence to date.

Springer Link – 14-Day Elemental Diet Is Highly Effective in Normalizing the Lactulose Breath Test

7. US National Library of Medicine – Staudacher HM, Whelan K: Altered gastrointestinal microbiota in irritable bowel syndrome and its modification by diet: probiotics, prebiotics and the low FODMAP diet.

8. US National Library of Medicine – Lazzini S, Polinelli W, Riva A, Morazzoni P, Bombardelli E: The effect of ginger (Zingiber officinalis) and artichoke (Cynara cardunculus) extract supplementation on gastric motility: a pilot randomized study in healthy volunteers.

9. Pimentel, Am J Gastroenterology 2000, 2003)(Pimentel, 2006)

10. Small intestinal bacterial overgrowth syndrome– World Journal of Gastroenterology Jan Bures, Jiri Cyrany, […], and Marcela Kopacova

11. Castiglione F, Rispo A, Di Girolamo E, Cozzolino A, Man- guso F, Grassia R, Mazzacca G. Antibiotic treatment of small WJG| www.wjgnet.com

12. Lin HC. Small intestinal bacterial overgrowth: a framework for understanding irritable bowel syndrome. JAMA 2004; 292: 852-858 – Lupascu A, Gabrielli M, Lauritano EC, Scarpellini E, San- toliquido A, Cammarota G, Flore R, Tondi P, Pola P, Gas- barrini G, Gasbarrini A. Hydrogen glucose breath test to detect small intestinal bacterial overgrowth: a prevalence case-control study in irritable bowel syndrome. Aliment Pharmacol Ther 2005; 22: 1157-1160

13. pimentel M, Chow EJ, Lin HC. Eradication of small inte- stinal bacterial overgrowth reduces symptoms of irritable bowel syndrome. Am J Gastroenterol 2000; 95: 3503-3506

14. Ford AC, Spiegel BM, Talley NJ, Moayyedi P. Small intestinal bacterial overgrowth in irritable bowel syndrome: systematic review and meta-analysis. Clin Gastroenterol Hepatol 2009; 7: 1279-1286

15. Mann NS, Limoges-Gonzales M. The prevalence of small intestinal bacterial overgrowth in irritable bowel syndrome. Hepatogastroenterology 2009; 56: 718-721

16. Gastroenterology – William L Hasler, M.D: Lactulose breath testing, bacterial overgrowth, and IBS: just a lot of hot air?

17. Curr Opin Gastroenterol. 2014 May; 30(3): 332–338.  – Bile Acids and the Gut Microbiome – Jason M. Ridlon,1,2 Dae Joong Kang,1 Phillip B. Hylemon,1,2 and Jasmohan S. Bajaj2,3,*