≡ Menu


Diarrhea and IBS


Having diarrhea predominant irritable bowel syndrome (IBS-D) means you are chronically affected by frequent abdominal pain and urgent episodes of diarrhea (loose/watery stools). Often times you may experience gas and bloating as well.

These urgent episodes of diarrhea really can really affect your life, as you may have to plan activities around where the nearest bathroom is, or even miss out altogether.

IBS-D is a multi-factorial condition, meaning it may be caused by a few, or an interplay of a few, different causes.

Some common causes of IBS-D include:

  • Intestinal Dysbiosis
  • Small Intestine Bacterial Overgrowth (SIBO)
  • Bile Acid Malabsorption
  • Parasites
  • Food intolerances/malabsorption

Intestinal Dysbiosis

Intestinal dysbiosis refers to an alteration or imbalance of the microbes in your digestive tract. (Learn more about dysbiosis here).

Dysbiosis has been repeatedly reported in IBS-D patients, and it has been shown that IBS-D patients have a lower level of microbial diversity compared to healthy individuals. (1)

Decreased populations of beneficial bacteria in IBS-D patients, allows for a proliferation of more pathogenic species such as proteobacteria, streptococci and clostridia. These bacteria can damage the gut lining and alter anion secretions leading to more water entering the colon.

Bile Acid Malabsorption (BAM)

Bile acids are known as endogenous laxatives (endogenous meaning originating from within the body) because they trigger propulsive contractions in the bowel and bring water into the colon. (2)

In fact, a condition called bile acid malabsorption (BAM) is known to cause chronic diarrhea. This condition is caused by excess bile salts entering the colon rather than being absorbed in the small intestine, increasing the reabsorption of water and colonic movement, which results in diarrhea.

Studies show that bile acid malabsorption (BAM) accounts for at least 30% of patients diagnosed with functional diarrhoea and IBS-D. (3)

In healthy people, the primary bile acids are dehydroxylated in the colon by your microbiota. In people with bile acid diarrhea, dehydroxylation is decreased and the concentration of bile acids in the colon is markedly elevated leading to increased motility, water excretion and diarrhea.

A study of fecal samples from people with IBS-D found a significant increase in fecal primary bile acids compared to healthy controls. Researchers in this study also found dysbiosis, characterised by an increase of E.coli, a decrease in bifidobacteria, and a decrease in bacteria from the Leptum group. The Leptum group contains the bacteria responsible for the dehydroxylation of bile acids. (4)


Small Intestine Bacterial Overgrowth (SIBO) is, as its name implies, an overgrowth of bacteria in the small intestine, and studies implicate it as a potential cause of IBS-D. (Learn more about SIBO here)

A study on the role of SIBO in 87 patients with chronic diarrhea reported that SIBO was present in 33% of patients compared to 0% in healthy controls. (5)

Researchers have found that patients with SIBO had significantly elevated unconjugated bile acid levels in their stools (6), and another study found a predominance of bacteria in the small intestine that metabolise bile salts to unconjugated bile salts in patients with IBS-D. (7)

In addition, due to this overgrowth in the small intestine, particles of food that would normally be fermented by the bacteria in the large intestine begin to ferment in the smaller confines of the small intestine, producing excessive quantities of hydrogen and/or methane gas. The gases also have an effect on bowel motility, with excessive hydrogen production having a strong link to diarrhea. (8)


A chronic parasite infection can mimic many of the same symptoms of IBS-D. Medical investigators in Australia have found the parasite D. fragilis in patients suffering from IBS like symptoms. (9)

Many of the clinical symptoms associated with IBS are non-specific and have also been reported in patients infected with D. fragilis and B. hominis.  Anecdotal evidence suggests that many patients infected with these parasites are indeed being misdiagnosed as having IBS”. (10)

A study carried out in Norway on 82 patients that had been infected with Giardia showed that 66 of them (81%) had symptoms of IBS 12 to 30 months after they initially got the Giardia infection. The most common symptom subtype was diarrhoea-predominant IBS (47%). (11)

Food Intolerance/Malabsorption

An intolerance to gluten, lactose, or eggs may also be contributing to your diarrhea. As could malabsorption of certain carbohydrates and/or fats. A trial of eliminating these foods from your diet, and/or keeping a food diary will help you pinpoint which foods may be contributing to your symptoms. (Learn more about food and IBS here)

How do I find out what’s causing my diarrhea?

As you can see, the cause of your diarrhea can be complex and may involve a number of factors. To find an effective solution to your diarrhea it is vital to find its root cause. Based on your presenting symptoms and history, there are a number of lab tests we may use to find the cause of your symptoms, including:

How is it treated?

Once we have a better idea of whats causing your diarrhea, we begin a treatment plan using diet, herbal medicines, nutritional supplements,  and lifestyle changes. This plan works by:

  • Removing foods from your diet that cause inflammation, feed the wrong bacteria/yeasts/parasites and irritate the gut wall.
  • Removing any abnormal growth of bacteria, yeasts and/or parasites in your gut.
  • Restoring beneficial bacteria and re-establishing healthy bacterial balance in your gut.
  • Reducing inflammation and repairing the lining of your gastrointestinal tract.

What next?

To learn more about the testing and treatment options available to you we recommend you take a free 15 minute phone consultation with our Naturopath. During this call you can learn more about our treatments and have any questions you may have answered. This call is to determine if we are a good fit for one another rather than a history or complete consultation. There is no obligation, and no strings attached.

It is quick and easy to book your free 15-minute phone consultation using our online calendar. Just click the link below, choose a date and time convenient for you, enter your details, and our Naturopath will call you at your chosen time. Book here




  1. Ian M Carroll, et al. Molecular analysis of the luminal – and mucosal – associated intestinal microbiota in diarrhea predominant irritable bowel syndrome. Am J Gastrointest Liver Physiol Nov 2011; 301 (5): G799- G807.
  2. Bajor A, Gillberg PG, Abrahamsson H. Bile acids: Short and long term effects in the intestine. Scand. J. Gastroenterol 2010; 45: 645-664.
  3. DiBaise JK, et al. Bile Acids: An Underrecognized and Underappreciated Cause of Chronic Diarrhea. Practical Gastroenterology 2012; 32-44.
  4. Duboc, et al. Increase in fecal primary bile acids and dysbiosis in patients with diarrhea-predominant irritable bowel syndrome. Neurogastroenterol Motil (2012) 24, 513–e247.
  5. Teo M, et al. Small bowel bacterial overgrowth is a common cause of chronic diarrhea. J. Gastroenterol. Hepatol. 2004; 19 (8): 904-9.
  6. Masclee A, et al. Unconjugated serum bile acids as a marker of small intestinal bacterial overgrowth. Eur. J. Clinical Invest. 1989; 19 (4): 384-9.
  7. Dukowicz AC, et al. Small Intestinal Bacterial Overgrowth a comprehensive review. Gastroenterol. Hepatol. 2007; 3 (2): 112-122.
  8. 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.
  9. Giacometti A, Cirioni O, Fiorentini A, Fortuna M, Scalise G (1999). “Irritable bowel syndrome in patients with Blastocystis hominis infection”. Eur. J. Clin. Microbiol. Infect. Dis. 18 (6): 436–9. 33.
  10. Borody TJ, Warren EF, Wettstein A, Robertson G, Recabarren P, Fontela A, Herdman K, Surace R, 2002. Eradication of Dientamoeba fragilis can resolve IBS-like symptoms. J Gastroenterol Hepatol 17 (Suppl): A103.
  11. Hanevik K, Dizdar V, Langeland N, Hausken T. Development of functional gastrointestinal disorders after Giardia lamblia infection. BMC Gastroenterol. 2009; 9: 27.


The Digestive Wellness Clinic
12 Junction St Woollahra, NSW 2025 Tel: (02) 8001 6344