Why Diarrhea Keeps Coming Back (Even When You’re Doing Everything Right)

And the overlooked driver most people miss

You Fix Your Diet… And It Still Happens

You clean up your food. You try low FODMAP. You cut out triggers.

And yet urgency is still there, loose stools come back, and it feels unpredictable.

At some point, it starts to feel like that old “Diarrhea… Diarrhea…” song we all remember…

“When you’re sliding into first and you feel something burst…”

Except this time, it’s not funny anymore.

This is the moment most people get told, “It’s just IBS.”

But when symptoms don’t respond the way you expect, it raises a more important question:

Are you targeting the right thing?

Because sometimes it’s not about what you’re eating.

It’s about what your body is doing with it.

A Different Way to Think About Diarrhea

Most people think diarrhea is caused by food sensitivities, stress, or “bad digestion.”

But there’s another driver that often gets missed:

Bile acids.

Bile acids are meant to be recycled through a tightly regulated system. When that system breaks down, they can become an irritant instead of a tool for digestion.[1,4]

That shift changes the conversation.

Instead of focusing only on food, it starts to highlight whether your digestive system is functioning the way it’s designed to.

What’s Actually Happening

The Science

Bile acids are produced in the liver and released into the small intestine to help digest fat. Under normal conditions, approximately 95% are reabsorbed in the terminal ileum and returned to the liver in a continuous cycle.[1,4]

When this process is disrupted, excess bile acids can pass into the colon, where they stimulate water and electrolyte secretion and accelerate colonic transit. This can result in diarrhea, urgency, and abdominal discomfort.[1,2,4]

This process is regulated by a feedback system. When bile acids are reabsorbed, they stimulate ileal FGF19 signaling, which suppresses hepatic bile acid synthesis. When that feedback is impaired, bile acid production continues, and excess bile acids continue to reach the colon.[2,4]

Bile acids also interact with the gut microbiome, and bile acid pool composition and microbiome structure appear to influence one another.[1]

Saying It Plainly…

Your body is designed to reuse bile acids in a controlled loop.

When that loop breaks, they end up in the wrong place and irritate your gut.

That irritation pulls in water and speeds everything up, leading to diarrhea and urgency.

This is also why symptoms can feel inconsistent.

You can eat the same meal on different days and have completely different outcomes.

It’s not just the food.

It’s how your body is handling it.

Why This Gets Misdiagnosed as IBS

IBS is diagnosed using symptom-based criteria, not a biological marker.[3]

That means it often becomes a label applied when no clear answer has been identified.

But research tells a different story.

Approximately one-quarter to one-third of patients meeting accepted criteria for IBS-D have bile acid malabsorption, and reviews report evidence of bile acid diarrhea in 25% to 50% of patients with functional diarrhea or IBS-D.[1,4,5]

If no one is looking for it, it gets missed.

Where This Connects to SIBO

Bile acid issues rarely exist on their own.

They often overlap with:

• small intestinal bacterial overgrowth (SIBO)
• microbial imbalance
• impaired motility

These systems interact.

When one is off, it can affect the others.

This is why addressing a single layer does not always fully resolve symptoms.

How Do You Actually Address Bile Acids?

Once you understand what’s actually driving this, treatment becomes more targeted.

But it is important to be clear:

There is not just one fix.

There are three main ways to approach bile acid-related symptoms.

1. Bind the Bile Acids

This is the most direct approach.

There are medications designed to bind bile acids in the gut, preventing them from irritating the colon. For the right patient, this can significantly reduce diarrhea and urgency.

Bile acid sequestrants have been shown to effectively reduce symptoms in patients with bile acid malabsorption.[1,6]

But this approach treats the effect.

It does not explain why the system broke in the first place.

2. Reduce How Much Bile Is Released

Diet can play a role.

Lower-fat dietary intervention has been associated with improvement in urgency, bloating, lack of control, and bowel frequency in patients with bile acid malabsorption.[7]

This can make symptoms more manageable.

But it does not fix the loop.

3. Support the System Around It

This is where most people miss the bigger picture.

Because bile acid issues rarely exist on their own.

They are influenced by:

• the microbiome
• how the gut is moving
• how the gut lining responds

Bile acids interact directly with both microbial activity and intestinal function, which means disruptions in these systems can increase symptom severity.[1,4]

When these systems are off, bile acids are more likely to end up in the wrong place and cause symptoms.

This is also where approaches that support the broader gut environment come in.

For example, Atrantil does not directly alter bile acid recycling, but it helps reduce fermentation, gas, and microbial imbalance, which can improve the overall conditions under which bile acids function.[8,9]

When the environment improves, the system often becomes easier to regulate.

So, How Do You Fix It?

The real answer is:

You don’t just fix bile acids.
You fix the system they are part of.

For some people, that means binding bile acids.

For others, it means reducing the load through diet.

But for many, it means stepping back and looking at:

• How the gut is moving
• How microbes interact
• How the system regulates itself

Because if those layers are not addressed, symptoms tend to come back.

The Real Takeaway

Bile acids are not the only issue.

They are part of a system.

And for many people, symptoms do not come from a single cause but from multiple overlapping factors occurring at the same time.

That is why a cause-based approach works better than guessing.

And why asking “what’s actually driving this?” is the question that changes everything.

When you fix the environment, the system starts to fix itself.

Listen to the Full Podcast

In this episode of the Gut Check Project, Dr. Ken Brown breaks down why IBS is overused, how bile acids contribute to symptoms, and what clinicians often miss.

References

1. Camilleri M. Bile acid diarrhea: pathophysiology, diagnosis, and management. Gut Liver. 2015 May;9(3):332-40. doi:10.5009/gnl14358.
2. Walters JRF, Tasleem AM, Omer OS, Brydon WG, Dew T, le Roux CW. A new mechanism for bile acid diarrhea: defective feedback inhibition of bile acid biosynthesis. Clin Gastroenterol Hepatol. 2009 Nov;7(11):1189-94. doi:10.1016/j.cgh.2009.04.024.
3. Lucak S. Diagnosing irritable bowel syndrome: what’s too much, what’s enough? MedGenMed. 2004 Mar 12;6(1):17.
4. Camilleri M. Advances in understanding of bile acid diarrhea. Expert Rev Gastroenterol Hepatol. 2014 Jan;8(1):49-61. doi:10.1586/17474124.2014.851599.
5. Slattery SA, Niaz O, Aziz Q, Ford AC, Farmer AD. Systematic review with meta-analysis: the prevalence of bile acid malabsorption in the irritable bowel syndrome with diarrhea. Aliment Pharmacol Ther. 2015 Jul;42(1):3-11. doi:10.1111/apt.13227.
6. Wilcox C, Turner J, Green J. Systematic review: the management of chronic diarrhea due to bile acid malabsorption. Aliment Pharmacol Ther. 2014 May;39(9):923-39. doi:10.1111/apt.12684.
7. Watson L, Lalji A, Bodla S, Muls A, Andreyev HJN, Shaw C. Management of bile acid malabsorption using low-fat dietary interventions: a useful strategy applicable to some patients with diarrhea-predominant irritable bowel syndrome? Clin Med (Lond). 2015 Dec;15(6):536-40. doi:10.7861/clinmedicine.15-6-536.
8. Brown K, Scott-Hoy B, Jennings L. Efficacy of a Quebracho, Conker Tree, and M. balsamea Willd blended extract in a randomized study in patients with irritable bowel syndrome with constipation. J Gastroenterol Hepatol Res. 2015;4(9):1762-7. doi:10.17554/j.issn.2224-3992.2015.04.560.
9. Brown K, Scott-Hoy B, Jennings LW. Response of irritable bowel syndrome with constipation patients administered a combined quebracho/conker tree/M. balsamea Willd extract. World J Gastrointest Pharmacol Ther. 2016 Aug 6;7(3):463-8. doi:10.4292/wjgpt.v7.i3.463.