Bile Acid Malabsorption (BAM): Symptoms, Causes, and Management in the UK

Bile Acid Malabsorption (BAM), also known as Bile Acid Diarrhoea (BAD), is a digestive condition that occurs when the body fails to reabsorb bile acids correctly. Bile acids are produced in the liver and stored in the gallbladder. When you eat, these acids are released into the small intestine to help digest fats. Normally, around 95% of these acids are reabsorbed at the end of the small intestine (the terminal ileum) and returned to the liver.

In patients with BAM, these acids remain in the large intestine. Because bile acids are irritants, they cause the colon to secrete water and salts, leading to urgent, watery stools. In the UK, health experts estimate that a significant number of people living with chronic diarrhoea may have BAM rather than traditional Irritable Bowel Syndrome (IBS).

The primary symptom of BAM is chronic, watery diarrhoea that persists for weeks or months. Unlike some other gut concerns, BAM symptoms are often very specific in their presentation:

• Urgency: A sudden, intense need to use the toilet.
• Watery Stools: Stools are often pale, greasy (steatorrhoea), or very yellow.
• Postprandial Pain: Abdominal cramping shortly after eating, especially fatty meals.
• Bloating and Wind: Excess gas due to the presence of acids in the colon.
• Accidents: Faecal incontinence can occur due to the extreme urgency.

It is important to note that symptoms may be mistaken for IBS-D. However, BAM symptoms often occur regardless of stress levels and are more directly linked to fat intake.

Medical professionals in the UK categorise BAM into three distinct types based on the underlying cause:

Type 1: Secondary to Ileal Disease

This occurs when the terminal ileum (the end of the small intestine) is damaged or removed. Common causes include Crohn’s disease or surgical resection.

Type 2: Primary (Idiopathic) BAM

This is the most common form seen in UK GP surgeries. There is no obvious damage to the bowel, but the body produces too much bile acid or the reabsorption mechanism simply fails. This is the type most frequently misdiagnosed as IBS.

Type 3: Other Gastrointestinal Conditions

This can occur due to other digestive issues such as coeliac disease, chronic pancreatitis, or following gallbladder removal (cholecystectomy).

If you present with chronic diarrhoea, your GP will likely first rule out infections, coeliac disease, and inflammatory bowel disease through blood and stool tests. According to NICE (National Institute for Health and Care Excellence) guidelines, the gold standard for diagnosing BAM in the UK is the SeHCAT scan.

The SeHCAT test involves swallowing a small capsule containing a synthetic bile acid. A scan is performed, and then repeated seven days later to see how much of the bile acid your body has retained. A retention rate of less than 15% is usually indicative of BAM. While the SeHCAT test is not available in every single UK hospital, it remains the most reliable diagnostic tool compared to 'trial by medication'.

Management of BAM focuses on reducing the amount of bile acid reaching the colon and neutralising what does get through. The two main pillars of treatment are:

• Low-Fat Diet: Since bile acids are released to digest fat, eating less fat (typically less than 40g per day) reduces bile acid production. It is often helpful to work with a registered dietitian.
• Bile Acid Sequestrants: These are medications that bind to bile acids in the gut, preventing them from irritating the colon. Common examples in the UK include colestyramine (often a powder mixed with water or juice), colesevelam (tablets), and colestipol.

Many patients find that their symptoms improve significantly within days of starting sequestrant medication, which can be life-changing for those who have suffered from chronic diarrhoea for years.

If you are experiencing persistent changes in your bowel habits, it is essential to seek medical advice. You can speak to a GP online to discuss your symptoms in a calm, private environment. An online doctor can help by:

• Reviewing your symptom history to see if they align with BAM or IBS.
• Ordering private blood tests to rule out coeliac disease or anaemia.
• Discussing whether a referral for a SeHCAT scan or to a gastroenterologist is appropriate.
• Providing advice on lifestyle adjustments and low-fat dietary changes.

Seeking help early can prevent complications like dehydration or nutrient malabsorption and help you regain control over your daily life.