Bile Is a Hormone, Not Soap | The Angry Gut, Chapter 23

What does bile do · Gallbladder

What Does Bile Do? It Gives Your Liver Its Orders

Bile emulsifies fat, but its main job is signaling: it tells your liver when to stop and your gut hormones when to fire. Remove the reservoir and the timing changes, which is measurable in some ways and not others.

What does bile do? Almost every answer you have been handed is about grease: bile breaks up fat so you can absorb it. That is true and it is the small half of the job. Bile also carries instructions, and the organ it instructs is your liver. Bile Is a Hormone, Not Soap, the Chapter 23 video for The Angry Gut by Dr. Gurpreet Singh Padda, MD, MBA, MHP, and Ami Michelle Grimes, works through the biology. The measuring question is the one worth bringing to an appointment: which parts of this can be put on a number, and which cannot.

What does bile do? It sends instructions, not just detergent

Put a primary bile acid onto human ileal tissue, the last stretch of small intestine, at a dose an ordinary meal produces, and the gene for a hormone called FGF19 switches on 350-fold. In a living person that signal runs on a clock: it climbs after eating, peaks 90 to 120 minutes behind the meal-driven rise in bile acids, and tells the liver to ease off. Fast, and the rhythm disappears.

Notice the direction of the conversation. The gut measures what arrived and tells the organ upstream how much to send next. Your gut is the first brain here, and the liver is taking orders from it, not the other way around. Nothing about that arrangement fits the schoolroom picture of bile as a fluid pushed downhill to dissolve a fried egg.

Why this reaches your blood sugar and your appetite

The same molecule hits a second receptor on the hormone cells of the bowel. When a bile salt was placed against those cells in ten people with obesity and type 2 diabetes, blood glucose fell by up to 3.8 mmol/l and the food eaten at the next unrestricted meal fell by up to 47%. Two days of an oral bile acid in healthy women raised brown fat activity and whole-body energy expenditure.

The cleanest proof that this is signaling rather than digestion is a binding resin that stays in the lumen. Nothing about it enters the bloodstream, so it never reaches the pancreas. Pooled across 17 trials, in a combined 2,950 patients, it still pulled down HbA1c, the average blood sugar reading, by half a percentage point, 0.55% to be precise. A substance your body cannot take up, acting on a receptor in your intestine, moved your blood sugar.

There is a behavioral layer under all of this, and it was prescribed. For decades anyone with a touchy gallbladder was told to keep fat low and keep the organ quiet. Fat arriving in the duodenum is the signal that empties a gallbladder, so a quiet one is a full one, and bile that sits still concentrates. The advice produced the stasis that the surgery later collected.

What changes after gallbladder removal?

The gallbladder is not a bag. Its lining carries the message for that same hormone at roughly 250-fold the level of the nearby small intestine. Remove it and bile acid production rises at least two-fold while the daily rhythm of the hormone flattens out.

The symptom that follows is a timing problem rather than a hormone shortage, and that distinction has been tested directly: when investigators looked for a link between the hormone content of the removed gallbladder and anyone’s bowel habit, they did not find one. What changes is delivery. A gallbladder saves bile between meals and releases it as a bolus when fat arrives; without one, bile trickles all day into a bowel built to receive it in pulses, more of it passes downstream, and the colon reads bile acids as an order to secrete water. That is the loose, urgent stool after a fatty meal.

Then the number that should embarrass the system. Among 9,439 people who had the operation, 202, or 2.1%, were ever investigated for diarrhea afterward. Of those who were tested, 62.8% had bile acid diarrhea, which is named, testable and treatable. Those figures come from an audit of patients a clinician already suspected, so they describe how rarely the question gets asked rather than how common the condition is.

The bile tests are real, and they are not Measura tests

Measura [Cardiometabolic and Autonomic Health Analysis] is built around blood work, body composition and resting metabolism, plus vascular, autonomic, small-fiber, balance and cognitive measurement. Bile acid testing is not in that library, and neither is gallbladder imaging, the nuclear scan that reports an ejection fraction, or breath testing. Those belong to your physician and a gastroenterologist, and the retention scan used in Europe is not licensed in the United States, which is why an American conversation often ends up being about a supervised trial of a binder with a defined endpoint instead. Any of that is a prescribing decision for your own doctor, not something to start or stop on your own.

What can be measured in the same person

What Measura can do is measure the terrain that grew the stone in the first place and the consequences you are living with now. Bile acids sit inside energy regulation, so the metabolic picture is not a side issue here.

Laboratory panels document fuel handling, inflammation and liver and kidney status in blood, which is where the stone-growing terrain shows up.
Bioimpedance body composition separates muscle from fat, so months of restricted eating and avoided meals can be seen rather than guessed at. Body composition, not BMI explains why that distinction matters.
Indirect calorimetry measures what you burn at rest instead of estimating it, which matters when weight has drifted since the operation.

None of those results is a diagnosis. They go to your physician, alongside the bowel history, so the decisions get made with numbers in the room.

What to ask for at your next visit

When the stool change began: before the operation, weeks after it, or months after it.
Whether your original pain was the classic biliary pattern or an atypical one.
If an ejection fraction was measured, what it was and which infusion protocol produced it.
Whether testing for bile acid diarrhea is available where you live, and if not, what a supervised trial with a stop date would look like.
Whether your metabolic picture has ever been measured, not just your gallbladder. Insulin resistance and metabolic health covers that ground.

Every study behind these numbers, with its limits stated, is in the book companion for The Angry Gut. The version written for physicians is the screening view of post-surgical complications.

Frequently asked questions

Can Measura test my bile acids or my gallbladder?

No. Bile acid testing, gallbladder ultrasound and the nuclear scan that produces an ejection fraction are different tests, arranged by your physician or a gastroenterologist. What can be measured here is the metabolic, vascular, autonomic and body-composition picture in the same person, which is where the terrain behind gallstones shows itself. See what Measura actually measures.

Why would loose stools start months after gallbladder surgery?

Because the change is in timing rather than in an organ failing. Without a reservoir, bile arrives steadily instead of in a burst after fat, more of it reaches the colon, and the colon answers bile acids by secreting water. The interval before symptoms appear varies, which is one reason the connection gets missed. How long that gap runs before anyone tests is in the screening view of post-surgical complications.

Does bile really affect blood sugar and weight?

The signaling does. In ten people with obesity and type 2 diabetes a bile salt lowered glucose and cut how much they ate at the following meal, and a binder confined to the bowel moved HbA1c by 0.55% in a pooled analysis covering 2,950 patients across 17 trials. That is why the metabolic picture belongs in this conversation. Read about metabolic rate and energy.

Is an irritable bowel label ever wrong after this operation?

It can be incomplete. In one audit only 2.1% of 9,439 people who had the operation were ever investigated for diarrhea, and most of those tested turned out to have bile acid diarrhea. A label that closes the file is different from a label that opens a test, and the questions you bring matter. See questions worth asking your doctor.

What should I bring to the visit?

A dated timeline of the stool change, the operation date, your original pain pattern, any ejection fraction result, your full medication list and a note of which foods trigger symptoms. Preparation changes what a single appointment can settle, and it keeps the conversation on measurement rather than on labels. Read how to prepare.

What is the main function of bile?

Bile emulsifies fat, but its main job is signaling. After a meal, bile acids reaching the last stretch of small intestine switch on a hormone called FGF19, which peaks 90 to 120 minutes behind the meal-driven rise in bile acids and tells the liver to ease off. The same molecules act on the hormone cells of the bowel, which is how bile reaches your blood sugar and your appetite.

Where is bile stored?

In the gallbladder. It saves bile between meals and releases it as a burst when fat arrives in the duodenum, the first part of the small intestine. Without a gallbladder, bile trickles into the bowel all day instead of arriving in pulses, more of it passes downstream, and the colon reads bile acids as an order to secrete water. That is the loose, urgent stool after a fatty meal.

Measure the terrain, not just the organ

Ask about laboratory, body composition and resting metabolism testing so your physician can see the metabolic picture behind your gallbladder history in numbers.

Send a message

4477 Woodson Rd, Suite 201, St. Louis, MO 63134. Monday to Friday, 9:00 a.m. to 5:00 p.m. Please do not send symptoms, diagnoses or images through a web form — a website form is not a secure medical channel. Send your name and number and we will call you back.

References

Zhang, J. H., Nolan, J. D., Kennie, S. L., Johnston, I. M., Dew, T., Dixon, P. H., Williamson, C., & Walters, J. R. F. (2013). Potent stimulation of fibroblast growth factor 19 expression in the human ileum by bile acids. American Journal of Physiology. Gastrointestinal and Liver Physiology, 304(10), G940-G948. https://doi.org/10.1152/ajpgi.00398.2012
Lundåsen, T., Gälman, C., Angelin, B., & Rudling, M. (2006). Circulating intestinal fibroblast growth factor 19 has a pronounced diurnal variation and modulates hepatic bile acid synthesis in man. Journal of Internal Medicine, 260(6), 530-536. https://doi.org/10.1111/j.1365-2796.2006.01731.x
Adrian, T. E., Gariballa, S., Parekh, K. A., Thomas, S. A., Saadi, H., Al Kaabi, J., Nagelkerke, N., Gedulin, B., & Young, A. A. (2012). Rectal taurocholate increases L cell and insulin secretion, and decreases blood glucose and food intake in obese type 2 diabetic volunteers. Diabetologia, 55(9), 2343-2347. https://doi.org/10.1007/s00125-012-2593-2
Hansen, M., Sonne, D. P., Mikkelsen, K. H., Gluud, L. L., Vilsbøll, T., & Knop, F. K. (2017). Bile acid sequestrants for glycemic control in patients with type 2 diabetes: A systematic review with meta-analysis of randomized controlled trials. Journal of Diabetes and Its Complications, 31(5), 918-927. https://doi.org/10.1016/j.jdiacomp.2017.01.011
Barrera, F., Azócar, L., Molina, H., Schalper, K. A., Ocares, M., Liberona, J., Villarroel, L., Pimentel, F., Pérez-Ayuso, R. M., Nervi, F., Groen, A. K., & Miquel, J. F. (2015). Effect of cholecystectomy on bile acid synthesis and circulating levels of fibroblast growth factor 19. Annals of Hepatology, 14(5), 710-721. https://pubmed.ncbi.nlm.nih.gov/26256900/
Farrugia, A., Attard, J. A., Hanmer, S., Bullock, S., McKay, S., Al-Azzawi, M., Ali, R., Bond-Smith, G., Colleypriest, B., Dyer, S., Masterman, B., Okocha, M., Osborne, A., Patel, R., Sallam, M., Selveraj, E., Shalaby, S., Sun, W., Todd, F., … Arasaradnam, R. P. (2021). Rates of bile acid diarrhoea after cholecystectomy: A multicentre audit. World Journal of Surgery, 45(8), 2447-2453. https://doi.org/10.1007/s00268-021-06147-8
Wedlake, L., A’Hern, R., Russell, D., Thomas, K., Walters, J. R. F., & Andreyev, H. J. N. (2009). Systematic review: The prevalence of idiopathic bile acid malabsorption as diagnosed by SeHCAT scanning in patients with diarrhoea-predominant irritable bowel syndrome. Alimentary Pharmacology & Therapeutics, 30(7), 707-717. https://doi.org/10.1111/j.1365-2036.2009.04081.x