A Comprehensive Guide to Inflammatory Bowel Disease: Symptoms, Causes, Diagnosis, Treatment & Prevention

Inflammatory bowel disease (IBD) is the name given to a group of conditions that cause chronic inflammation in the gut. The prevalence of IBD is increasing across the world in both adolescents and adults, and it can result in pain, uncomfortable symptoms, and a reduction in quality of life.

In this article, we’ll look closely at what IBD is, the causes, symptoms, and what you can do to treat or prevent it.

What is inflammatory bowel disease (IBD)?

Inflammatory bowel disease is an umbrella term for a group of chronic, long-term conditions that cause recurring inflammation in the gastrointestinal (GI) tract. The term is mainly used to describe two conditions; ulcerative colitis and Crohn’s disease.

When the inner lining of the gut, also known as the intestinal mucosa, becomes inflamed it can cause several debilitating symptoms, such as abdominal pain, diarrhoea, weight loss, and an exaggerated immune response.

IBD is a lifelong condition that often emerges in early life, the prevalence of which has grown substantially since the latter half of the 20^th century, with Europe and North America reporting the highest rates. Generally, IBD is considered idiopathic, so the actual cause is unknown, but research is bringing to light some potential factors involved in the pathogenesis of the disease[i].

Types of inflammatory bowel disease

The two main types of IBD are ulcerative colitis and Crohn’s disease.

Ulcerative colitismainly affects the colon.

Crohn’s diseasecauses inflammation along any part of the gastrointestinal tract or digestive system.

There are also subtypes of these diseases which may be categorised by where they occur or by how it is examined. For example, microscopic colitis requires a microscope to be seen[ii].

What’s the difference between IBD and irritable bowel syndrome (IBS)?

There may be some confusion about the difference between IBD and IBS because both are digestive conditions but they are distinct. The table below helps to classify the differences between IBS and IBD.

IBS	IBD
Syndrome or group of symptoms	Disease
Does not cause inflammation	Causes severe inflammation and permanent damage to the intestines
No sign of abnormality or disease in diagnostic examination	Disease is visible during diagnostic examination
No increased risk of colon cancer	Associated with an increased risk for colon cancer

 

What’s the prevalence of IBD?

Research is continuing to show a rise in the prevalence of inflammatory bowel disease. According to the EFCCA, 10 million people across the world are living with IBD[iii].

Symptoms of IBD

The symptoms of IBD can vary from person to person, depending on where and how severe the inflammation is. Some of the common symptoms include:

• Diarrhoea
  • With or without blood
  • With or without mucous
  • May occur at night
  • Incontinence is common
• Abdominal pain
• Cramping
• Bloating
• Extreme urgency to go to the toilet
• Weight loss
• Anaemia
• Some people with ulcerative colitis can experience constipation if the disease affects their rectum
• Feeling or being sick (Crohn’s disease)

IBD symptoms are not just limited to the digestive tract. For example, some skin problems can occur before any symptoms associated with the gastrointestinal system appear. Common manifestations include erythema nodosum (EN) which affects between 3 and 10% of ulcerative colitis patients and 4-15% of Crohn’s disease patients. EN appear as bruise-like nodules on the skin which can be very painful[iv].

Another manifestation of IBD is in the eye, with approximately 10% of people with IBD experiencing eye issues[v]. Most of the eye problems linked with IBD are treatable and are not associated with a significant risk of vision loss.

Types of eye disorder associated with IBD are:

• Uveitis – painful inflammation of the middle layer of the eye wall called the uvea. Symptoms may include pain, blurred vision, redness, and sensitivity to light. If untreated, uvea may progress to glaucoma and vision loss.
• Keratopathy – abnormality of the cornea that usually occurs in people with Crohn’s disease. Doesn’t usually require treatment because it is not associated with pain or vision loss.
• Episcleritis – a condition where the outer coating of the white of the eye, called the episcleral, becomes inflamed. Symptoms include pain, redness, and inflammation.
• Dry eyes – a deficiency in vitamin A may cause dry eyes and an increased risk of infection due to a lack of tear production. Vitamin A supplements may help to resolve dry eyes^iv.

Causes of IBD

The exact cause of inflammatory bowel disease is unknown but there are believed to be several different factors that could contribute to its development.

Let’s take a look at some of the reasons why you might develop diseases such as Crohn’s or ulcerative colitis.

Genetics

There is some evidence that suggests IBD is hereditary. For example, some studies show that between 5% and 20% of people with IBD who have a parent, child, or sibling with ulcerative colitis or Crohn’s disease, also have it[vi].

A review by Graham & Xavier (2020) revealed that IBD is a complex genetic disease that results from a combination of multiple genetic and environmental factors that can upset the immune-microbiome axis[vii].

The immune system

The immune system could also play a key role in the development of IBD. The immune system is the body’s main defence against opportunistic pathogens responsible for causing infection and disease.

So, if an infection enters the GI tract, the immune system is responsible for triggering a response to remove it from the body, which may include inducing inflammation. Once the infection has cleared, the inflammation should go away if you are otherwise healthy.

However, in IBD patients, inflammation occurs without the presence of an infection, causing the immune system to attack its own cells. Some research shows that the development of autoimmune disease is slightly greater in Crohn’s disease than ulcerative colitis[viii].

It’s important to remember that the development of IBD is complicated, but studies show that proinflammatory mediators have a key role in its onset. Th17 cells, specific immune cells usually involved in an inflammatory response against extracellular pathogens, play an important part in the stimulation and maintenance of colonic inflammation in people with IBD[ix]. Therefore, some researchers are focused on better understanding the role of Th17 cells in the development of IBD in an attempt to develop a targeted and effective treatment.

Smoking

Believe it or not smoking is one of the main risk factors for developing Crohn’s disease. Yet, it is shown to lower the risk of ulcerative colitis – this is not a positive for smoking as it has numerous negative health outcomes.

A 2020 study in Taiwan involving 700 IBD patients assessed the effect of smoking on the development and disease outcomes. The results showed that smoking prevalence was lower in ulcerative colitis patients, and although these patients had fewer hospital admissions, they had higher cancer and mortality rates compared to non-smokers. 

The study also found that smoking Crohn’s disease patients had higher rates of stricturing diseases and an increased risk of requiring surgery compared to non-smokers. So, although smoking may lower the occurrence of ulcerative colitis, it is associated with a greater cancer and mortality risk. While for Crohn’s disease, smoking can mean patients are more likely to require surgery for their condition[x].   

Environmental factors

As well as genetics, immunity, and smoking, the environment could also contribute to the development of inflammatory bowel disease.

Kaplan et al. (2010) demonstrated that although being exposed to air pollution isn’t associated with the incidence of inflammatory bowel disease, residential exposures to sulphur dioxide (SO₂) and nitric oxide (NO2) could increase the risk of early onset ulcerative colitis and Crohn’s disease.

In 2014, Salim et al., hypothesised that the ingestion of air pollutants could initiate and accelerate the onset of inflammatory digestive diseases by altering the gut microbiome. The researchers suggested that this could happen via a combination of ways, including by increasing gut permeability, slowing down gut motility, and altering the composition of the microbiome[xi].

Pollution is not the only environmental factor that could play a part in the development of IBD, diet has also been implicated. Chiba et al. (2019) believe that diet induced dysbiosis is the most common environmental cause of IBD. For example, diets that are high in animal protein and low in fibre, like the Western diet, are associated with reduced microbial diversity which could increase the risk of developing chronic diseases, including IBD[xii]. Furthermore, a review by Rizzello et al. (2019) found that diet plays a key role in the development of inflammatory bowel disease, highlighting that certain food groups trigger inflammation. The review also found that individuals living in industrialised countries may also be more susceptible to IBD because of their genetic background and dietary choices[xiii].

Diagnosing IBD

To diagnose IBD, doctors must examine and analyse the clinical symptoms of the disease, often, at first by asking questions about your medical history and your bowel movements. This helps to build a picture of what you are experiencing on a daily basis and if you may be at greater risk because one of your relatives has been diagnosed with IBD. Your doctor may also ask you about your diet, activity status, and your daily routine before arranging some tests.

Blood and stool tests

Blood and stool tests may be used to help in the initial diagnosis. Some biomarkers found in these samples can be good indicators for the presence of inflammation. These tests may not tell you what is causing the inflammation to occur, but they may help your doctor determine if further testing is needed to see where it is coming from.

Some of the blood biomarkers of inflammation are c-reactive protein (CRP) and erythrocyte sedimentation rate (ESR). While calprotectin and lactoferrin are proteins found in your poo that can indicate gastrointestinal inflammation.

Endoscopy

Endoscopy examinations can play an important role in the diagnosis of IBD, help to rule out other conditions, and establish whether you have ulcerative colitis or Crohn’s disease[xiv].

An endoscopy is where a long, thin tube with a tiny camera on the end is inserted into your body to see inside. There are several types which may be used, such as:

• An upper GI endoscopy where a thin, flexible tube with a light and camera called an endoscope, is inserted through your mouth and down the oesophagus into your stomach and the duodenum. This diagnostic procedure is often used if Crohn’s disease is suspected.
• A colonoscopy involves inserting a similar tube into the body via your anus. This procedure allows the doctor to inspect the full length of your large intestine. Often, you will receive a sedative to help you relax.

X-ray and barium enema

X-rays are an effective way to see inside the body and can be useful for detecting blockages in the intestines. For a barium study, you’ll be given a contrast material to drink before the procedure. The barium is usually a chalky or milky liquid and while it is flowing through your GI tract, a series of x-rays will be taken[xv].

CT or MRI scans

As well as x-rays, other imaging methods such as CT or MRI scans can be useful for diagnosing IBD. These types of imaging can help to:

• Distinguish between ulcerative colitis and Crohn’s disease
• Monitor and track IBD manifestations outside the colon
• Visualise penetrating complications outside the bowel wall
• Monitor disease progression when a person diagnosed with IBD is experiencing symptoms[xvi]

CT or computerised tomography scans use x-rays and computers to provide detailed images of the structures inside the body, including organs, blood vessels, and bones[xvii]. Magnetic resonance imaging or MRI scans, on the other hand, use magnetic fields and radio waves to generate detailed images of inside the body[xviii].

What treatments are available for IBD?

There are several treatment options available for IBD, ranging from conventional therapies like medication through to new therapeutic strategies as well as education and dietary changes.

Medication

Pharmacological treatments are a first step in managing IBD for many people, particularly anti-inflammatory drugs which help to reduce the inflammation within the GI tract. The problem with these is some people can experience side effects which may mean the treatment isn’t suitable for them.

The pharmacological interventions that could be prescribed include:

• Corticosteroids
• Aminosalicylates
• Immunomodulators
• Biologics

Lifestyle changes

Lifestyle changes are important if you are diagnosed with IBD and can help to control the symptoms of the disease.

Exercise

Being active may be linked to a lower risk of developing IBD, especially Crohn’s disease. However, for people who have already been diagnosed, the disease can be so debilitating that it affects their fitness and ability to participate in physical activity. For example, approximately half of IBD patients report that IBD affects their fitness and between 15% and 40% are obese[xix].

Yet, research shows that moderate-intensity exercise is safe and may have benefits for people who do not have severe IBD[xx]. This type of exercise can have an anti-inflammatory effect within the body by reducing fat and the circulating levels of pro-inflammatory cytokines. In IBD specifically, moderate-intensity exercise can reduce the expression of TNF-α and IL-1β, both of which are believed to play a significant role in disease progression.

Activities could include:

• Walking
• Yoga
• Pilates
• Cycling
• Dancing
• Swimming

Diet

The food you eat could increase or even decrease your risk of developing IBD. That’s why it is important to analyse what you eat. At Layer Origin Nutrition, we offer a free Picture-based Food Frequency Nutrition Assessment & Personalised Recommendations to give you a comprehensive overview of your nutrient intake.

The Western diet, for example, is believed to increase circulating levels of pro-inflammatory cytokines as well as change the composition of the gut microbiome, resulting in low-grade, chronic inflammation in the gut. A diet that is high in pro-inflammatory foods is a risk factor in the development of ulcerative colitis[xxi] and Crohn’s disease[xxii].

Because diet has such a significant role in microbial composition within the gut, it is considered an important contributory factor for the development and maintenance of disease. However, some diets have been investigated for their beneficial effects on disease with mixed results. These include:

• The specific carbohydrate diet (SCD) – isn’t recommended for IBD patients.
• The Mediterranean diet – research has shown improvements in quality of life in IBD patients, including a reduction in flare-ups. The diet also has many other health benefits.
• The low Fodmap diet – often recommended for people with IBS but not currently IBD. Further research is needed to evaluate the efficacy of a low FODMAP diet to control gut inflammation.
• The gluten-free diet – some research shows no significant difference in IBD in people who followed a gluten free diet and those who did not[xxiii].

Keep a food diary to help identify any triggers that may be contributing to flare-ups or the onset of symptoms. If you spot any patterns, you may be able to begin eliminating trigger foods from your diet.

Supplements

Recent research supports the use of prebiotics, probiotics, and other dietary supplements in response to gut dysbiosis. But there are limited guidelines in response to IBD. Nutrient deficiencies are common in IBD patients with over 50% of people reporting them. Although deficiency is more common in Crohn’s disease than ulcerative colitis, the most common are:

• Iron
• Vitamin B12
• Vitamin D
• Vitamin K
• Folic acid
• Selenium
• Zinc
• Vitamin B6
• Vitamin B1

Iron deficiency is the most common cause of anaemia in IBD patients[xxiv]. Supplementation may be required to help resolve the deficiency and, in some cases, may help to improve the outcome of IBD[xxv].

Some people choose to try omega-3 fatty acids, which are essential fatty acids that you must acquire from your diet. There are two important omega-3s called eicosapentaenoic acid (EPA) and docosahexaenoic acid (DHA). Both are important in lowering acute inflammation and may be useful in the treatment and management of IBD.

But that’s not all. In recent years, supplementation to target the gut has also gained traction, mainly because of the vital role the gut microbiome plays in our health and disease status. Dysbiosis has been associated with the erratic immune responses witnessed in inflammatory diseases, including IBD as well as rheumatoid arthritis and psoriasis.

For this reason, pre- and probiotics have been studied for their potential therapeutic use in such disease states. However, current guidelines for their use in the treatment of IBD are lacking because of study limitations, such as small sample sizes[xxvi]. Thus, more research is needed to fully determine the role specific prebiotics, probiotics, and synbiotics can play in the treatment of IBD. Yet, there are some early promising results with some specific probiotic strains in ulcerative colitis, like VSL#3 and Escherichia coliNissle 1917[xxvii].

Human milk oligosaccharides for IBD

Human milk oligosaccharides (HMOs) are a specific type of prebiotic, abundant in human breast milk. Although HMOs have numerous health benefits for the infant microbiome, more recent research shows that they have magic powers for adults, too.

The research is in its early stages for IBD, but a recent 2023 case study found that a HMO based synbiotic formulation with probiotics, like Lactobacilliand Bifidobacteria,could provide a holistic approach for IBD remission[xxviii].

Furthermore, because IBD is a multifactorial disease that is often associated with changes in the composition of the gut microbiome, targeting specific areas of the gut can be useful. For example, an imbalanced gut can mean a low production of health-promoting short-chain fatty acids (SCFAs), particularly butyrate which is renowned for its anti-inflammatory properties. Changes in butyrate can affect the outcomes of target IBD drug therapy[xxix], but low levels may also contribute to an inflamed state. And although butyrate supplementation on its own is unlikely to cure IBD, it may help to correct some of the immune abnormalities and improve the gut barrier dysfunctions associated with IBD.

What’s this got to do with butyrate? Well, HMOs help to feed gut bacteria species, like Bifidobacteria which produce SCFAs that butyrate-producers thrive on. This process is known as cross-feeding, and nourishing butyrate-producers means their activity will increase, resulting in higher butyrate production and could help to restore some balance to the gut environment.

If you’re looking to support the health of your gut, check out our range of HMO products in our shop!

Surgery

Surgery is sometimes a necessary treatment for IBD and can mean the partial or full removal of the inflamed bowel. There are different types of surgery that target different areas of the colon or the different types of inflammatory disease.

Because IBD patients have a higher risk of colorectal cancer, it’s likely your doctor will  regularly monitor you with routine colonoscopies. These will also allow them to see how the disease is progressing or how well it is being managed. Your doctor will discuss any surgery requirements with you.

Can you prevent inflammatory bowel disease?

If you have inherited IBD, then it is not possible to prevent its development. However, there are things you can do to help reduce your risk or to help manage its severity. These include:

• Following a fibre and nutrient rich diet
• Participating in regular exercise
• Quitting smoking

Summary

Inflammatory bowel disease (IBD) is an umbrella term for a group of diseases that are responsible for chronic inflammation in the digestive tract. The two main diseases are ulcerative colitis and Crohn’s disease.

IBD can cause a variety of uncomfortable symptoms and can be as far reaching as the eyes and skin. Although the exact cause of IBD is unknown, there are several different contributory factors that have been identified, including genetics, lifestyle, and environmental.

An imbalanced gut microbiome has been shown to increase the likelihood and severity of gut inflammation. You can help to support the balance of your colonic ecosystem by eating a fibre rich diet, getting plenty of exercise, an

 

Written by: Leanne Edermaniger, M.Sc. Leanne is a professional science writer who specializes in human health and enjoys writing about all things related to the gut microbiome. 

 

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