IBS, a look into the role of bile acids

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Devin Roen is a dietetic intern at the Jill Roberts Center for Inflammatory Bowel Disease

By Devin Roen

Greetings friends!

Who wants to learn about bile acid diarrhea (aptly shortened “BAD”), a condition commonly found in patients with IBS?

Better question: who doesn’t?!

Let’s start with a few basics.

Bile—a digestive juice used to help breakdown fats—is made in the liver and stored in the gallbladder. When you eat something containing fat, your liver pumps bile into the gallbladder and the gallbladder squirts bile onto the fat entering the small intestine.

Bile looks and acts similarly to dish soap, breaking up big fat droplets into smaller blobs. Bippity-boppity-presto, we end up with lots of baby fat droplets that our pancreatic enzymes can further break down into bits small enough for our guts to absorb.

When the bile is no longer needed, it gets reabsorbed in the last part of the small intestine (a.k.a. the ileum) and recycled back to the liver. Once the first of the bile gets reabsorbed, the body sends a signaling molecule (called FGF19) to the liver telling it that it’s time to wrap up bile production.

And they all lived happily ever after… ?

Not always. Things can happen that result in too few or too many bile acids.

Too few bile acids mean we wouldn’t be able to digest fat, and all that fat would end up in the stool leading to some stinky, greasy poo.

On the flip side, too many bile acids in the gut has a well-known laxative effect, pulling water into the gut and causing diarrhea, gas and bloating.

The three main causes of BAD are:

  • Inflammation or resection of the distal ileum (if the bile reabsorption site is out of commission then the bile cannot be reabsorbed/recycled)
  • FGF19 deficiencies (not enough “off switch” to tell the liver to chill out, and it will go on a bile-making frenzy resulting in more bile than we can reabsorb even when the distal ileum is still intact)
  • Gallbladder removal (no collecting pouch to control when and how much bile is pumped into the gut)

There are many triggers for diarrhea, so the best way to find out if bile acids are to blame is to get tested. There are a few different ways to test for BAD, but the main one available in the U.S. involves a 48-hour fecal fat collection. Your doctor can tell you more about this test.

If you test positive for BAD or suspect that you might be at risk for overproducing or under absorbing bile acids, then you might benefit from eating more soluble fiber.* Soluble fiber has many health benefits, one of them being to help mop up excess bile.

Here are a few great sources of soluble fiber: Beans/legumes, oats, some vegetables (e.g. Brussel sprouts, asparagus, potatoes), fruit (e.g. oranges, apples, avocado) and chia seeds.

Want to learn more about BAD and other causes of IBS? Check out this great article from the UK.

FOOTNOTES
*Bile acid diarrhea may require a more aggressive approach involving medications called bile acid sequestrants (e.g. Cholestyramine). These medications work similarly to soluble fiber, by binding excess bile.

+It’s a good idea to discuss these foods with your gastroenterologist or nutritionist as many of them can contribute to abdominal bloating and/or gas. Either way, make sure to introduce them gradually to allow the gut bacteria time to adjust.

DISCLAIMER: This information is for educational purposes only and is not intended as medical advice. Talk with your healthcare provider about any questions you may have related to your condition or your treatment plan.

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