Microscopic Colitis

Microscopic Colitis: An Evidence-Based Overview

Microscopic colitis is an often-overlooked cause of chronic diarrhoea, with symptoms that significantly affect quality of life. Despite its subtle presentation, it can be effectively managed with appropriate diagnosis and treatment strategies. This blog delves into what microscopic colitis is, its causes, symptoms, diagnostic methods, treatment options, and the role of probiotics, prebiotics, postbiotics, nutrition, and lifestyle modifications in managing the condition.

What Is Microscopic Colitis?

Microscopic colitis is an inflammatory condition of the colon that causes chronic, watery diarrhoea. Unlike other types of colitis, microscopic colitis doesn’t produce visible abnormalities during a colonoscopy. Instead, diagnosis relies on microscopic examination of colon tissue obtained through biopsies.

There are two main subtypes:

• Collagenous Colitis (CC): Characterised by a thickened layer of collagen beneath the lining of the colon.
• Lymphocytic Colitis (LC): Defined by an increased number of lymphocytes (a type of white blood cell) in the colon lining.

Both subtypes share similar symptoms and treatment approaches.

What Causes Microscopic Colitis?

The exact cause remains unclear, but it’s believed to result from a combination of factors (source):

1. Immune System Dysregulation: Microscopic colitis is considered an autoimmune-related condition, often occurring alongside other autoimmune diseases like celiac disease, thyroid disorders, and rheumatoid arthritis. A retrospective study found autoimmune disorders were present in 40% of patients with lymphocytic colitis (source).
2. Medications: Certain drugs have been linked to the development of microscopic colitis, including:
   • NSAIDs (e.g., ibuprofen)
   • Proton pump inhibitors (PPIs)
   • SSRIs (antidepressants)
   • Beta-blockers
3. Infections: Past gastrointestinal infections may trigger immune responses that lead to chronic inflammation.
4. Genetic Predisposition: Family history of inflammatory bowel conditions increases risk.
5. Bile Acid Malabsorption: Excess bile acids can irritate the colon lining, contributing to symptoms.
6. Smoking and alcohol consumption.
7. Obesity.
8. Appendicitis.
9. Dysbiosis – an imbalance in the gut microbiome.
10. Autoimmune disease – such as ankylosing spondylitis (AS), psoriasis, Hashimoto’s disease, Graves–Basedow disease, and type 1 diabetes.

Gut Microbiome And Microscopic Colitis

Research shows that infections, particularly with certain bacteria and viruses, significantly raise the risk of developing MC, especially collagenous colitis (CC):

• Clostridioides difficile (C. difficile): People who’ve had a C. difficile infection are three times more likely to develop CC, with this increased risk lasting for at least three years.
• Other Triggers: Infections from noroviruses, Escherichia species (E. coli), and bacteria like Campylobacter concisus and Campylobacter jejuni are also linked to MC, though to a lesser extent.

These microorganisms can trigger inflammation by:

• Producing pro-inflammatory cytokines (chemical signals that promote inflammation).
• Reducing beneficial bacteria in the gut, which normally help maintain intestinal health.

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The Importance of Protective Gut Bacteria

Healthy gut bacteria, such as Lactobacillus, Bifidobacterium, and Akkermansia muciniphila, play a crucial role in defending the gut. They help:

• Produce lactic acid and bacteriocins (natural antimicrobial substances)
• Generate short-chain fatty acids (SCFAs) that strengthen the gut lining
• Support the intestinal barrier, preventing harmful substances from entering the bloodstream

Research has shown that the most consistent result among the studies was a decreased Akkermansia genus in faecal samples (source).

When these protective bacteria are reduced, the gut becomes more vulnerable to inflammation and damage.

Microscopic Colitis After Fecal Microbiota Transplantation (FMT)

Although rare, some cases of MC have been reported following fecal microbiota transplantation (FMT), a procedure where healthy bacteria from a donor’s stool are transplanted into the patient’s gut to treat conditions like C. difficile infections.

Researchers believe this may happen because:

• In people with abnormal immune responses, the sudden introduction of new bacteria may trigger immune cells (like lymphocytes) to move into the gut and cause inflammation.
• The rapid increase in bacterial diversity might lead to an overproduction of bacterial byproducts (metabolites), which could contribute to gut inflammation.

Symptoms of Microscopic Colitis

An increased incidence of bile salt diarrhoea and coeliac disease is associated with microscopic colitis. (source)

Microscopic colitis symptoms overlap with those of IBS and up to 50% of patients with this disease meet the Rome III criteria for IBS. A recent meta-analysis of microscopic colitis in IBS patients shows an MC prevalence of 7.1–7.4%. On the other hand, the prevalence of microscopic colitis in patients with diarrhoea from other causes was as high as 10.9% (source).

While symptoms can vary, the hallmark feature is chronic, non-bloody, watery diarrhoea, which may occur several times daily. Additional symptoms include (source):

• Nocturnal bowel movements.
• Abdominal pain and cramping.
• Urgency to defecate.
• Fecal incontinence.
• Bloating and gas.
• Unintentional weight loss (in severe cases).
• Fatigue.

Symptoms may fluctuate, with periods of remission and flare-ups, sometimes triggered by certain foods, stress, or medications.

Bile Acid Malabsorption (BAM) and Microscopic Colitis

About 4 in 10 people with microscopic colitis also experience a condition called bile acid malabsorption (BAM).

What Are Bile Acids?

Bile acids (or bile salts) are substances that help your body digest fats. When you eat, especially fatty foods, your liver and gallbladder release bile acids into the upper part of your digestive system. These bile acids break down fats as the food moves through your small intestine.

Normally, when bile acids reach the end of the small intestine, most of them are reabsorbed into the body and sent back to the liver through the bloodstream to be reused.

What Happens in BAM?

In bile acid malabsorption, the gut doesn’t properly reabsorb these bile acids. Instead, they travel into the colon, where they can irritate the lining of the bowel. This irritation disrupts the colon’s ability to absorb water effectively, leading to the production of large amounts of watery diarrhoea—a common symptom in both BAM and microscopic colitis.

In simple terms, BAM causes your body to lose too much water in your stool, resulting in chronic diarrhoea.

How Is Microscopic Colitis Diagnosed?

“General practitioners and gastroenterologists should always take microscopic colitis into consideration when diagnosing a patient with chronic diarrhoea.” (source)

Accurate diagnosis involves several steps:

1. Medical History and Physical Exam: Assessment of symptoms, medication use, and underlying conditions.
2. Stool Tests: To rule out infections, parasites, and inflammatory markers.
3. Colonoscopy with Biopsies: While the colon appears normal, multiple biopsies from different sections are critical. Histological examination reveals characteristic features of collagenous or lymphocytic colitis.
4. Blood Tests: To check for associated autoimmune conditions, anemia, or signs of malnutrition.

Treatment Options for Microscopic Colitis

Management focuses on symptom relief, reducing inflammation, and addressing underlying causes.

1. Medication Management

• Anti-Diarrhoea Agents: Loperamide helps control diarrhoea in mild cases.
• Bile Acid Binders: Cholestyramine is effective if bile acid malabsorption is involved.
• Anti-Inflammatory Drugs: Budesonide, a corticosteroid with minimal systemic effects, is the first-line treatment for moderate to severe cases.
• Biologics: Infliximab, Adalimumab, and Vedolizumab.

2. Discontinuation of Triggering Medications

If symptoms coincide with the use of certain drugs (e.g., NSAIDs, PPIs, selective serotonin-reuptake inhibitors), discontinuation can lead to improvement (source).

The Role of Probiotics, Prebiotics, and Postbiotics

Emerging evidence suggests that modulating the gut microbiota may benefit patients with microscopic colitis.

Probiotics

Probiotics, particularly strains like Lactobacillus and Bifidobacterium, help:

• Reduce intestinal inflammation
• Improve gut barrier function
• Modulate immune responses

A review by Selvamani et al. (2022) highlighted the potential of probiotics in managing inflammatory bowel diseases, including microscopic colitis, although more targeted studies are needed.

Recommended product: Advanced Acidophilus and Bifido & Fibre. These two strains of probiotic has been found to be helpful in micrscopic colitis (source). An open labelled study in 30 patients from India, with the probiotic mixture VSL#3, suggested that the probiotic could induce short-term clinical response and improve associated symptoms (source).

To understand how to choose the right probiotic read our article The Best Probiotic For Gut Health.

Prebiotics

Prebiotics feed beneficial gut bacteria, promoting a balanced microbiome. However, they may worsen symptoms like bloating in sensitive individuals.There is currently no evidence on the use of prebiotics in microscopic colitis but it would seem logical to consider them. Prebiotics may support rebalancing of the gut microbiome and support gut lining integrity – both may be beneficial to the condition.

Postbiotics

Postbiotics are bioactive compounds produced by probiotic bacteria, such as short-chain fatty acids (SCFAs), which:

• Support anti-inflammatory pathways.
• Enhance gut barrier integrity.
• Reduce oxidative stress.

A recent review published in 2024 discussed how postbiotics may offer therapeutic benefits, particularly in inflammatory bowel diseases (source).

The most researched postbiotic is butyrate. You can learn all about butyrate in our blog What Is Butyrate.

Diet and Microscopic Colitis: What You Need to Know

When it comes to microscopic colitis, there’s no one-size-fits-all diet. While there’s no strong evidence that specific foods trigger symptoms for everyone, some people do notice that certain foods make their symptoms worse. Common triggers include fatty foods, spicy dishes, and foods high in fiber, but reactions can vary from person to person.

Many people with microscopic colitis have questions about gluten and dairy. Here’s what you should know:

Should I Avoid Gluten?

People with microscopic colitis are over 50 times more likely to have celiac disease compared to the general population. Celiac disease is an autoimmune condition where your body can’t tolerate gluten, a protein found in wheat, barley, and rye.

To find out if you need to avoid gluten:

Your doctor will order a blood test to check for celiac disease.
If the test is positive, they may recommend an upper gastrointestinal (GI) endoscopy with a biopsy to confirm the diagnosis.
It’s important not to start a gluten-free diet before these tests, as it could affect the results.

Should I Avoid Dairy?

If your diarrhoea gets worse after consuming dairy products like milk, cheese, or yogurt, you might be lactose intolerant. This means your body has trouble digesting lactose, a natural sugar found in dairy.

How to find out:

• Keep a food diary to track what you eat and how you feel after meals.
• A doctor may suggest a lactose breath test to confirm lactose intolerance.

Important Advice

Before making any major changes to your diet, talk to your doctor or a dietitian. They can help you:

• Identify food triggers without unnecessary restrictions
• Ensure you’re still getting all the essential nutrients
• Plan balanced meals if you need to avoid gluten or dairy

Personalising your diet with professional support can help you manage symptoms effectively while maintaining good nutrition.

Calcium

A study by Sandler et al. explored how diet, particularly calcium intake, affects the risk of developing microscopic colitis (MC). The researchers found that people who consumed more calcium had a lower risk of developing MC. In fact, those with the highest calcium intake had a risk factor of 0.22, compared to a risk factor of 1.0 in those who consumed the least calcium (source).

The amount of calcium linked to the greatest reduction in risk was about 1,055 mg per day for men and 800 mg per day for women (source).

So, how does calcium help?

• Supports Gut Bacteria: Higher calcium intake appears to boost the levels of Actinobacteria, a type of beneficial bacteria that helps maintain a strong and healthy gut lining.
• Reduces Inflammation: Calcium also promotes the production of short-chain fatty acids (SCFAs), which are important for gut health. SCFAs support the metabolism of colon cells, have anti-inflammatory properties, and help protect against the development of MC (source).

In simple terms, getting enough calcium in your diet may help keep your gut healthy and lower your risk of microscopic colitis.

Lifestyle Strategies

• Stress Management: Chronic stress exacerbates gut inflammation. Techniques like mindfulness meditation, yoga, and CBT have shown benefits.
• Regular Exercise: Promotes healthy gut motility and reduces inflammation.
• Adequate Hydration: Essential to counteract fluid loss from diarrhea.

When to Seek Medical Advice

While microscopic colitis is rarely life-threatening, seek medical attention if you experience:

• Severe dehydration
• Significant weight loss
• Blood in stools
• Persistent or worsening symptoms despite treatment

Final Thoughts

Microscopic colitis is a manageable condition with the right approach. Combining medical therapy with dietary strategies, microbiome modulation, and lifestyle changes offers the best outcomes. Continued research into probiotics, prebiotics, and postbiotics holds promise for future therapies.

For personalised management, consult a healthcare professional specialising in gastrointestinal disorders.