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What is Inflammatory Bowel Disease (IBD)?

What is Inflammatory Bowel Disease (IBD)?

Inflammatory bowel disease (IBD) is the term for a group of gastrointestinal conditions, all of which – as the name suggests – causes inflammation of the digestive tract. This inflammation causes a number of digestive upsets, most commonly including diarrhoea and abdominal pain. However, the symptoms can vary greatly from one person to the next and can range from mild to severe.
If you have IBD you’ll typically have periods when you have few or no symptoms – called remission – alternating with other times when your symptoms are more severe and persistent, called a flare-up. But while IBD is a lifelong condition it doesn’t usually shorten life expectancy. If you manage your symptoms well you may be able to keep flare-ups to a minimum and have long remission periods when you have a normal quality of life.
The two main types of IBD are Crohn’s disease and ulcerative colitis. Of these, ulcerative colitis is the most common, affecting about one in 400 people in the UK (Crohn’s disease, on the other hand, affects around one in 700) (i).
Both of these main types of IBD have similar symptoms, so their treatments are similar too. But whether you’re diagnosed with ulcerative colitis or Crohn’s disease will depend on which part of your digestive tract is affected:

  • In ulcerative colitis, only the large intestine – or colon – is affected.

  • Crohn’s disease can affect any part of the digestive tract, from the mouth to the anus (though according to the NHS the most common part affected is the last section of the small intestine (ileum) or the large intestine (colon) (ii)).


What causes Inflammatory Bowel Disease (IBD)?

We don’t know the exact cause of IBD, but these days it’s mostly thought that it’s a result of a combination of genetic, immune system and environmental causes.
The inflammation in IBD is thought to be caused by the immune system overreacting to foreign invaders such as bacteria, viruses, fungi and other microorganisms. Normally, the immune system launches an attack on potentially harmful microorganisms to stop them doing any further damage to the body. But if you have IBD your immune system responds inappropriately, causing more harm than good.
Why anyone’s immune system might react in this way could be because they have inherited genes that make them susceptible to IBD. In fact experts reckon that as many as one in four people with IBD have a family history of the disease (iii).
Meanwhile certain environmental factors are often thought to be triggers for these inappropriate immune responses. Triggers can include things like stress, depression, having an inactive lifestyle (iv) and eating a diet high in fat and processed foods (v).

What are the most serious complications of IBD?

As well as having the symptoms of IBD, people with the condition also have a higher risk of developing bowel cancer. So if you’ve been diagnosed with IBD – especially ulcerative colitis – your doctor will usually recommend regular bowel cancer screening. Other possible complications can include the following:

  • Weight loss and malnutrition caused by poor absorption of food

  • Bowel obstruction (stricture) caused by narrowing of the bowel (this is more common in Crohn’s disease than ulcerative colitis) 

  • Anaemia

  • Fistulas (abnormal passages) and ulceration around the anus

  • Toxic megacolon (an enlarged, swollen colon that’s more common in ulcerative colitis than Crohn’s disease)

  • Perforated or ruptured bowel wall

  • Problems affecting other parts of the body, including the joints, skin, eyes, liver and bones


Are there treatments for Inflammatory Bowel Disease?

We still don’t have a cure for IBD, but there are treatments that aim to relieve the symptoms and keep those affected in remission for as long as possible.

Diet and lifestyle   

If you’re diagnosed with IBD your doctor or specialist may recommend dietary changes that could be helpful. This may, for instance, include reducing the amount of fibre in your diet and having more frequent, smaller meals. Some people are advised to follow a low-residue diet, which is a very restricted diet with low amounts of fibre. If you’re on a low-residue diet you will probably have to take vitamin and mineral supplements to make up for the nutrients you’re missing.
Other things that may be helpful include drinking plenty of fluids, staying physically active, avoiding your triggers whenever possible, giving up smoking and finding ways to manage your stress levels.


There are several medicines that doctors prescribe for patients with IBD, including drugs that help reduce inflammation in the digestive tract, immune suppressing medicines to stop the immune system over-reacting, antibiotics, corticosteroids and antibody-based treatments that target certain parts of the immune system (biologic therapy).


Some people with IBD need surgery because their symptoms don’t improve or no longer improve when they take medicines, or because their digestive system has been so badly damaged it needs to be repaired. According to the NHS, the number of people with IBD who eventually need surgery for their condition includes one in five people with ulcerative colitis and up to 75 per cent of people with Crohn’s disease (v). 

What is ulcerative colitis?

You can get it at any age but most people with ulcerative colitis develop the condition when they’re relatively young – most cases are first diagnosed in people aged between 15 and 25 years old (vi). It affects men and women equally, but some people are more likely to develop it than others, including:

  • People living in urban rather than rural areas

  • People from developed rather than developing countries

  • People of white European descent, especially those with Ashkenazi Jewish ancestors (from Eastern Europe and Russia), and black people

There are different types of ulcerative colitis depending on how much of the colon is affected. For instance, if you have proctitis, only the rectum is affected by inflammation. Left-sided (distal) colitis, on the other hand, is where inflammation affects the rectum as well as the left side of the colon. Extensive or total colitis (pancolitis) is where most or all of the colon is affected.

What are ulcerative colitis symptoms?


  • Recurring diarrhoea, often with blood, mucus and pus

  • Abdominal pain, including severe cramps

  • Frequent bowel movement

Less common symptoms can include tiredness and fatigue, nutritional deficiencies (which can lead to conditions such as anaemia), poor appetite and weight loss, joint pain, mouth ulcers, eye irritation and areas of painful, swollen, red skin. Severe cases of ulcerative colitis can also cause a fast or irregular heartbeat, shortness of breath and fever.

When should you see your doctor about ulcerative colitis?

If you have any of the symptoms of ulcerative colitis it’s important to see your GP for a diagnosis. They will usually arrange for you to have tests at a hospital that examine your colon. If you’re diagnosed with ulcerative colitis, the treatment you’ll get will depend on how bad your condition is.
For more information about ulcerative colitis, including how the symptoms are treated, read our guide

What is Crohn's Disease?

Like ulcerative colitis, Crohn’s disease is most commonly (but not always) diagnosed in younger people – usually those aged between 15 and 30 (vii). One in 10,000 people are diagnosed with Crohn’s disease every year in the UK, with smokers and people who’ve recently had their appendix removed among those most likely to develop it. And like ulcerative colitis it’s also more common in white people of European descent, including those descended from Ashkenazi Jews (viii).

What are the symptoms of Crohn's Disease?


  • Symptoms vary from one person with Crohn’s disease to the next, ranging from mild to severe. Some of the most common include:

  • Diarrhoea and abdominal pain

  • Tiredness and fatigue

  • Weight loss and loss of appetite

  • Mouth ulcers

  • General feelings of being unwell

Some symptoms are a result of your body not digesting food and absorbing nutrients effectively, and there’s also a risk that you may develop anaemia from losing blood with diarrhoea.
Also like ulcerative colitis there are different types of Crohn’s disease, which are named according to which part or parts of the digestive tract are inflamed:

  • Crohn’s colitis (colon)

  • Ileal Crohn’s (ileum – the final part of the small intestine)

  • Gastroduodenal Crohn’s disease (stomach and duodenum – the first part of the small intestine)

  • Jejunoileitis (jejunum – the upper half of the small intestine)

  • Perianal Crohn’s (anus)

These different types of Crohn’s disease can cause different symptoms. The main symptom of Crohn’s colitis, for instance, is often blood-stained diarrhoea. Perianal Crohn’s, on the other hand, can often cause fissures (tears in the lining of the anal canal) and haemorrhoids.

Could my Crohn’s Disease symptoms instead be Irritable Bowel Syndrome (IBS)?

IBS – or irritable bowel syndrome – can cause some similar symptoms to Crohn’s disease and ulcerative colitis. However it’s not the same because it doesn’t cause inflammation, though some people with Crohn’s disease may develop IBS-type symptoms when they’re in remission – diarrhoea, for example. According to the charity Crohn’s & Colitis UK, IBS is more common in people with IBD than in the general population (ix).

You should see your GP if you have any of these symptoms:


  • You have blood in your stools

  • You’ve had diarrhoea that’s lasted seven days or longer

  • You have frequent cramps or stomach aches

  • You’ve lost weight without trying

Read more about the symptoms and treatment of Crohn’s disease in our guide What is Crohn’s disease?

What are the most common types of IBD?

Ulcerative colitis and Crohn’s disease are the two main types of IBD, accounting for the majority of cases. But there are a few other types too, including:

Inflammatory bowel disease unclassified

Also called IBD unclassified, IBDU or indeterminate colitis, this isn’t technically a different type of IBD. It is, rather, the term given to a condition that could be either ulcerative colitis or Crohn’s disease, where doctors haven’t been able to make an exact diagnosis.
Experts have found that an indeterminate diagnosis is given in 10 - 15 per cent of IBD cases (x), though researchers have also found up to 80 per cent of people diagnosed with IBDU will eventually be diagnosed specifically with either ulcerative colitis or Crohn’s disease (xi).
If you’re diagnosed with IBDU it shouldn’t affect your treatment, which is similar to that of ulcerative colitis and Crohn’s disease. Not all treatments will be available to you, however, since some treatments for ulcerative colitis (surgery, for instance) could do more harm than good if it turns out you have Crohn’s disease.

Microscopic colitis

Microscopic colitis is actually two similar conditions, namely lymphocytic colitis and collagenous colitis. It affects part of the digestive tract called the large bowel, which is the colon and rectum combined. If you have microscopic colitis, the inner lining of your large bowel becomes inflamed:

  • Lymphocytic colitis is where more white blood cells (lymphocytes) than usual are found in the inner lining.

  • Collagenous colitis can also have more white blood cells in the inner lining, but it’s also when the inner lining has a thick layer of collagen.

According to Crohn’s & Colitis UK, lymphocytic colitis affects slightly more people than collagenous colitis, though women are more likely to have collagenous colitis (with some people having both types at different times). Most people are diagnosed with microscopic colitis between the ages of 50 and 60, though you can develop it at any age. (xii).
Microscopic colitis affects the colon by reducing its ability to absorb liquid from waste matter. This can lead to a build-up of fluids in the gut, causing symptoms such as severe diarrhoea, abdominal pain, bloating, wind and fatigue.

Diversion colitis

People who’ve had surgery to treat certain diseases in the large intestine may develop a form of IBD called diversion colitis. The surgery in question is called a colostomy, where part of the bowel is diverted through an opening in the abdomen called a stoma. Diversion colitis develops in the part of the intestine that is no longer in use following the surgery, though scientists still don’t know why it happens. Symptoms include abdominal pain, a bloody or mucus discharge and fever. If the colostomy is temporary, the symptoms of diversion colitis will usually subside once the operation is reversed (that is, when the bowel is joined back together again).

Behçet’s disease

This is a rare autoimmune disease that causes inflammation of the blood vessels, which affects various different parts of the body including the digestive tract. It’s most commonly found in people who live in or originate from countries in the Middle East and East Asia, such as Turkey, Iran, Japan and China. When it affects the digestive tract Behçet’s disease can cause ulceration where the small intestine and large intestine meet, which can lead to symptoms such as abdominal pain, diarrhoea and bleeding. Treatment includes medications that help reduce the severity of symptoms.

Natural supplements for IBD

Living with any type of IBD can be a challenge, especially when you’re having a flare-up of your symptoms. There are, however, natural supplements that could be helpful, especially as you may not be able to absorb nutrients from food effectively.
For instance, taking a good-quality multivitamin containing a wide range of essential nutrients – including iron, calcium, vitamins A, B, D, E and K – could help prevent nutritional deficiencies caused by malabsorption (and, in the case of calcium, taking steroid medication in the long term). Find out more about multivitamin and mineral supplements in our guide to multivitamins and daily requirements. 


Curcumin – the active compound found in the curry spice turmeric – has been widely found to have an anti-inflammatory effect, and there is some evidence that it may help prevent flare-ups in people with ulcerative colitis (xiii). Researchers have also found it may be a safe and effective way of maintaining remission of ulcerative colitis symptoms when taken alongside medical treatments (xiv).

Soluble fibre

Types of soluble fibre such as fructo-oligosaccharides (FOS) may help maintain a healthy digestive tract by helping to feed live bacteria in the gut. Studies also suggest fermentable fibre – including FOS – may have an anti-inflammatory action in the gut (xv). If, however, your doctor or specialist has recommended that you follow a low-fibre diet, check with them first before trying a soluble fibre supplement.

Live bacteria

Other substances that may help maintain a healthy digestive environment are live (or ‘friendly’) bacteria such as acidophilus. Most commonly known as probiotics, these live bacteria have been found potentially useful for people with ulcerative colitis, with one study suggesting certain bacteria may be as effective at controlling the symptoms and preventing flare-ups as one particular medicine often prescribed for the condition called mesalazine (xvi). Other studies have found taking live bacteria may help maintain remission of ulcerative colitis symptoms (xvii) and relieve joint pain associated with IBD (xviii).

High-strength fish oils

A good-quality fish oil supplement may be useful for IBD symptoms, since it’s widely thought that the omega-3 fatty acids found in oily fish help reduce inflammation. Experts writing in the Annals of Gastroenterology, for instance, note several studies show omega-3 fatty acids may help weaken inflammatory processes (xix), Others have discovered they may help reduce inflammation caused by autoimmune disease (xx). There’s also some evidence that the omega-3 fatty acids found in oily fish may be helpful when you’re having a flare-up of ulcerative colitis (xxi).

Fish oil supplements are ideal if you can’t or don’t want to eat regular portions of oily fish such as salmon, pilchards, sardines, herring, mackerel or fresh tuna. And now you can also benefit from an omega-3 supplement if you’re a vegetarian or vegan too, thanks to the wider availability of supplements that contain the natural triglyceride (TG) form of omega-3, which is sourced from microalgae.
Inflammatory bowel disease is a lifelong condition. However with the right treatment as well as a healthy lifestyle and some help from the right nutritional supplements you may be able to spend longer and longer periods in remission, where your symptoms are minimal or even non-existent. This guide offers a brief overview of the essential information you should know to start managing your condition effectively. To discover more about other digestive conditions as well as a wide range of general health conditions, take a tour around our pharmacy health library



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Disclaimer: The information presented by Nature's Best is for informational purposes only. It is based on scientific studies (human, animal, or in vitro), clinical experience, or traditional usage as cited in each article. The results reported may not necessarily occur in all individuals. Self-treatment is not recommended for life-threatening conditions that require medical treatment under a doctor's care. For many of the conditions discussed, treatment with prescription or over the counter medication is also available. Consult your doctor, practitioner, and/or pharmacist for any health problem and before using any supplements or before making any changes in prescribed medications.

Our Author - Christine Morgan


Christine Morgan has been a freelance health and wellbeing journalist for almost 20 years, having written for numerous publications including the Daily Mirror, S Magazine, Top Sante, Healthy, Woman & Home, Zest, Allergy, Healthy Times and Pregnancy & Birth; she has also edited several titles such as Women’ Health, Shine’s Real Health & Beauty and All About Health.

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