The Overlap of Bile Acid Malabsorption & IBS

Bile acid malabsorption (often called bile acid diarrhea) is a condition where the body either produces too much bile acids or does not properly reabsorb bile acid in the small intestine, causing urgent, watery diarrhea. Because bile acid malabsorption’s symptoms are so similar to IBS-D, the diagnosis can often be missed.

What is bile acid malabsorption?

With regular digestion, the human body does an excellent job of making and storing bile acids and releases them from the gallbladder each time we eat to help us absorb fat and fat-soluble vitamins. About 97 percent of the bile acids we produce get reabsorbed at the very end of the small intestine (called the terminal ileum), where it meets the beginning of the colon. They can be used over and over as long as they continue to be reabsorbed. Talk about efficiency!

The absorption of bile acids is an important step, as bile acids that do not get absorbed move forward into the colon and can cause irritation. In some individuals, absorption of bile at the terminal ileum is poor, whereas, in others, they produce too much bile acid for their body to absorb all at once. This causes bile acid malabsorption (BAM) and subsequently, diarrhea. Other, secondary causes of BAM include having previous damage to the small intestine from conditions like celiac disease, inflammatory bowel disease, previous bowel surgeries, or small intestinal bacterial overgrowth (SIBO). For some people, bile acid malabsorption can also occur without a known cause.

Similarities between bile acid malabsorption and IBS

Bile acid malabsorption and diarrhea-predominant IBS have overlapping symptoms, making it difficult for physicians to initially diagnose this condition. Both BAM and IBS-D are characterized by:

• Urgency
• Watery diarrhea
• Bloating gas
• Abdominal pain

Most gastroenterologists will rule out other conditions via colonoscopy and other tests before diagnosing IBS or BAM. We frequently see patients diagnosed with IBS-D who may actually have BAM that was missed during screening and diagnosis. This is because the two conditions present VERY similarly.

To make matters more complicated, it is possible to have both diagnoses! Some studies report up to 50 percent of those with functional diarrhea or IBS-D have bile acid malabsorption.

Management options for bile acid malabsorption

Treatment options for BAM include a combination of pharmacological and lifestyle/diet changes.

The most reliable treatment for BAM is the use of bile acid sequestrant drugs. These medications bind to the unabsorbed bile acids in the colon and allow us to excrete them in our stool, preventing pulling water into the bowel and causing diarrhea. The dose of these medications can change depending on the individual, their specific symptoms, and even what they eat.

Although there is a diagnostic test for BAM, it isn’t often available outside of research. In many cases, it is safe and effective to treat empirically by simply trialing the use of a bile acid sequestrant drug. If an individual responds positively, we can observationally say that they experience bile acid malabsorption.

How Can Diet Help with Bile Acid Malabsorption?

Although bile acid sequestrant drugs are the powerhouse for treating BAM, dietary modifications can also help to improve chronic diarrhea associated with BAM. In particular, the following strategies have been linked to improved symptom outcomes in bile acid malabsorption:

• A diet low in poorly absorbed and highly fermentable carbohydrates (FODMAPs).
• Use of bulk-forming fiber supplements such as psyllium husk, a diet low in dietary fat - with less fat to “mop-up”, we release fewer bile acids and therefore have fewer symptoms associated with poor bile acid reabsorption. 
• Small, frequent meals as opposed to large meals.

Getting the Care You Need

You are an empowered partner in your own healthcare and you DO get a say. If you experience chronic, watery diarrhea, oily/greasy stool, and cramping talk to your doctor about the possibility of bile acid malabsorption.

It is also recommended to work with a registered dietitian to make sustainable dietary changes that will help to reduce secretions in the gut caused by excess bile acids.