What Is Bile Acid Malabsorption?
Bile Acid Diarrhea (BAD) sometimes called Bile Acid Malabsorption (BAM) is a condition that happens when your intestines can’t absorb bile acids properly, which causes watery diarrhea.
Bile is made in your liver and contains acids, proteins, salts, and more to help break down food and nutrients during digestion. This is released by the gallbladder into the small intestine. In healthy individuals, bile acids are reabsorbed in the large intestine and taken back to the liver. This cycle repeats itself multiple times throughout the day and typically, a very small amount of bile acids stay in the large intestine. Those that do stay will become part of your stool.
For those with BAD, there is a dysfunction in this resorption process, so the large intestine is filled with more bile salts. This increases motility (aka movement) and secretions, which results in urgent diarrhea and abdominal cramping.
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25% to 50% of patients with functional diarrhea or diarrhea-predominant irritable bowel syndrome (IBS-D) also have evidence of BAD, so this is something that could easily be missed with an IBS diagnosis.
There are 4 categories of BAD:
Type 1 includes any ileal disease that would prevent the reabsorption of bile acids from the terminal ileum, including Crohn’s disease, ileal resection, and radiation ileitis.
Type 2 is considered idiopathic, with no clear underlying cause and presents typically as chronic diarrhea or diarrhea-predominant irritable bowel syndrome (IBS-D).
Type 3 results from underlying diseases related to malabsorption such as chronic pancreatitis, celiac disease, and cholecystectomy (removal of the gallbladder), among others.
Type 4 includes conditions that result in excessive bile acid production and release without a clear source of impaired reabsorption, as seen in patients with hypertriglyceridemia or those taking metformin (a medication commonly used for diabetes).
There are currently 3 diagnostic tests for BAD:
Selenium homotaurocholic acid test (SeHCAT) is considered the current gold standard to diagnose BAD and is an ideal test for those with bile acid reabsorption issues - commonly seen with type II BAD. Unfortunately, this is not available in the United States.
Serum biomarkers of hepatic bile acid synthesis are convenient, but lack diagnostic accuracy on their own. Fasting serum C4 is appropriate as a screening tool and is available via commercial testing in the United States
Total and individual fecal BAs are measurements of total and individual fecal bile acids, and provide the most direct method of analyzing bile acids in stool as well as changes or primary and secondary bile acids in the colon. This would be the more direct way to identify BAD in the United States.
In addition to testing, a gastroenterologist would do a thorough assessment to identify what is going on and what the best treatment option(s) would be for you. Treatment may include bile acid binders (known as bile acid sequestrants) and/or FXR antagonists.
Diet can also play a role as fats will increase bile production. A lower fat diet, as well as spreading fats out throughout the day, may help. This would be individualized based on your personal symptoms, so this is best done with a digestive health dietitian. If you’re looking for a dietitian, you can schedule a consult call to see if our team would be the right fit for you!
Sources:
https://patient.info/digestive-health/irritable-bowel-syndrome-leaflet/bile-acid-diarrhoea
https://www.healthline.com/health/bile-acid-malabsorption#diagnosis
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