Crohn’s Disease

Overview of Crohn's disease

How common is Crohn’s disease?

Crohn’s Disease is one of the most common forms of Inflammatory Bowel Disease or IBD, affecting around 1 in every 650 people in the UK today. It can affect any part of the digestive system from the mouth to the anus, but is most commonly found in the small intestine and/or colon. Often occurring in patches, it causes inflammation, deep ulcers and scarring to the wall of the intestine. The cause or causes have not yet been identified, but both genetic factors and environmental triggers are likely to be involved; it’s slightly more common in women than in men, and it’s more common in smokers.

Interestingly, and for reasons that are not yet understood, there are certain groups in whom Crohn’s disease is much more common. In London, the most important group is Ashkenazi Jews who have a prevalence at least five times higher than the surrounding populations.

What is Crohn’s disease?

Crohn’s disease in an inflammatory condition that affects all parts of the digestive system.

The digestive system, also known as the gastrointestinal (GI) tract or gut, is composed of:

  • Mouth
  • Oesophagus – food gullet between mouth and stomach
  • Stomach
  • Small bowel
  • Large bowel (colon) including the rectum
  • Anus

Inflammation presents in a number of ways including pain, swelling and redness. Inflammation of the gut wall affects the ability of the body to absorb nutrients from food. It also has an impact of the ability of the body to excrete waste.

Inflammatory Bowel Disease (IBD)

Crohn’s disease is one of the two major types of inflammatory bowel disease. The other type is called ulcerative colitis. Both tend to affect people long-term.

Crohn’s disease is characterised by patchy inflammation anywhere along the gastrointestinal tract. This means inflammation can occur anywhere between the mouth and anus, but the inflammation may not be continuous. The most common sites affected by Crohn’s disease are the small intestine and/or large bowel (colon).

Ulcerative colitis is different. It only affects the large bowel and is continuous, always starting in the rectum and extending for a variable amount up through the large bowel.

There are other causes of inflammatory bowel disease such as microscopic colitis or collagenous colitis. Like Crohn’s disease and ulcerative colitis, the cause of these conditions is currently unknown.

One more cause of IBD is infective colitis. This is caused by certain bacterial or viral infections and can be treated using strong antibiotics. This is the least common form of chronic (long-term) IBD as it is usually a self-limiting illness.

How Common is Crohn’s?

Crohn’s disease affects approximately 1 in every 650 people in the UK. It is slightly more common in women than in men. It is also more common in smokers. Crohn’s disease is also more common in certain ethnic groups of people.

In London, the most important group is Ashkenazi Jews. The prevalence of Crohn’s in the Ashkenazi Jewish population is at least five times higher than the general population. In general, Crohn’s disease is more common in white and African-American individuals, and less common among Latino and Asian individuals.

Age of Onset

Crohn’s usually presents in the first half of a person’s life, typically between the ages of 10-40. There is a second peak of onset at around the age of 60. People who develop the disease later in life are usually less badly affected.

Recent data has shown that the burden of Crohn’s disease has increased significantly over the past 50 years, although it is unclear exactly why this has happened.


The symptoms experienced by patients with Crohn’s disease vary from mild to severe, and may also vary from person to person. An individual patient may also go through a phase of no symptoms (remission phase) followed by a phase with a lot of symptoms (relapse phase).

Unfortunately, there is no way to predict how long either phase will last, although the correct medicines can definitely help.

The symptoms experienced in Crohn’s disease can be classified as intestinal and extra-intestinal. Intestinal symptoms affect the gut whereas extra-intestinal symptoms affect other areas of the body. Examples of intestinal and extra-intestinal symptoms are listed in the table.

Tummy painFatigue (tiredness)
Diarrhoea (stools may also contain mucus or blood)Anaemia (a reduced number of red blood cells) – this can contribute to the feeling of tiredness
VomitingSwollen joints
Weight loss – this is due to reduced absorption of food, and possibly a reduced appetiteEye problems such as redness and inflamation
Mouth ulcersSkin sores and rashes

Crohn’s is a progressive disease


Over the last few years, with ever improving medicines, it has become clear that Crohn’s disease is a progressive disease. It tends to start with inflammation which affects the entire thickness of the bowel wall. Over time, the inflamed area can heal with scarring. This leads to narrowing (also known as stricture or stenosis) of this area of the gut. Immediately above this area the gut may be dilated as food is held up there. This is often reported in X-rays as ‘pre-stenotic dilatation’.


Whereas treatment of inflammation is usually very successful with the correct use of medicines, once a stricture has developed, it may sometimes only respond to surgery to remove it. Our approach is to reserve surgery as a last-resort treatment. Nonetheless around one in five sufferers currently end up with at least one operation within 10 years of diagnosis. As our medical treatments improve, this number is likely to fall over time.


Inflammation affects the entire thickness of the bowel wall. As the disease progresses further, holes may open in the bowel wall which allow food contents to leak out. These usually result in development of a fistula – an attachment between two areas of inflamed bowel wall which allows the liquid content from one area to flow into the other. Fistulae commonly occur between the small and large bowel which tend to sit next to each other in the abdomen. This may lead to diarrhoea. Fistulae can also open up into the abdominal wall, the area around the anus (per-anal area), or other place and if bacteria enter these, abscesses can develop. These frequently need to be drained under Xray guidance and rarely by surgery.

Our Approach to Treatment

Treating Crohn’s disease requires a series of complementary approaches:

  • Treating Symptoms
  • Preventing Complications
  • Caring for the Patient’s General Wellbeing

Treating Symptoms

It takes many years to master the treatment of Crohn’s disease. Approaches include judicious use of one or more of the following approaches:

  • Diet
  • Antibiotics
  • Steroids (we don’t like using these and only use them when there are clear reasons to do so)
  • Disease modifying agents, including azathioprine, methotrexate and biologics
  • Surgery

At the London Gastroenterology Centre, our specialist consultants can offer diagnosis and Crohn’s disease treatment in London, which may range from dietary treatment to surgical treatments, depending on the severity of your condition. These treatments can help to reduce your symptoms and deal with complications, and are aimed at improving your quality of life and keeping the condition in remission.

Crucially, we take the approach of ‘aggressive physician, conservative surgeon’. By this we mean that surgery should be considered as the last option in patients with Crohn’s and should only be used after medical approaches including diet and drugs have failed. To this end, we have specialist dietitians to advise you. We also have access to all the latest biological therapies, although there are limits on what insurance companies may pay for.

Preventing Complications

Untreated, Crohn’s disease can cause some nasty complications. The aim is therefore to ensure that the correct treatments are used early enough to prevent these. Our consultants are experts in the field and will always take the time to ensure that these issues have been thought about and discussed with our patients.

With ever more aggressive treatments being offered to prevent progression of Crohn’s disease, it is increasingly recognised that the treatments themselves can cause complications. Steroids can cause a lot of problems, particularly if they are used too frequently or for too long. The newer disease modifying drugs have recognised toxicities. As long as the doctor considers these and checks for them, most of the complications can be minimised or avoided completely. Our doctors will review your current treatment and advise if any complications need to be specifically screened for or treated.

Caring for the Patient’s General Wellbeing

Being unwell is difficult, particularly when you are young. There are many things that might be bothering you, from the way you feel in general (tired, pain, miserable) to managing your relationships and work. Having a good rapport is crucial in supporting you through this disease. Our doctors are happy to listen to your particular concerns. They will spend time with you to guide you through your own personal journey. Our goal is to help support you so that you can manage your disease and not let your disease manage you.

In our view, knowledge is power. That is why we strongly support the work of the charity Crohn’s and Colitis UK. This charity is run by patients and supported by doctors to ensure that sufferers have the information they need and access to the very best support available. In particular, their website describe the best up-to-date treatments available in a lot of detail. We recommend that you explore where you can read more about Crohn’s disease and other forms of IBD.

Step Up versus Step Down Treatment

Another important concept is step up versus step down treatment. Many doctors start with the lowest dose of drugs and build up. Traditionally, the starting point is to use steroids. If these fail, second line drugs such as azathioprine are used. Only if these fail, are biologics such as Infliximab or Humira used. There is increasing evidence that this approach leads to worse outcomes long term.

We assess our patients carefully. We will often suggest a much more aggressive treatment initially to get the disease under excellent control. Long term management then becomes around dietary control to keep the patient well. This means that people need to take less steroids long term and yet remain in better health.

Crohn’s disease needs a partnership between the patient and their physician. We pride ourselves on offering a patient-centred approach. We listen and guide. We offer wide ranging support. Our patients are very happy with their interactions with the doctors. Please see our testimonials page and find out what patients say about our service.

To find out more about Crohn’s disease treatment at our London clinic, or to discuss treatment with our specialists, please get in touch using the form below.

What impact will Crohn’s disease have on my life?

It is common to feel a little nervous about telling your close friends and family about your condition. It can also feel frustrating at times when people don’t understand what you are going through, or when people tell you not to worry, when the symptoms you experience are real and troublesome.

For many Crohn’s sufferers who are on the right medication, the condition is mostly manageable and it is possible to continue working and socialising as normal. For some patients, however, the symptoms may become quite troubling, causing them to feel they have to change their lifestyle considerably.

Although you may feel uncomfortable telling your employer about your condition, it can be very helpful in the long-run, as they will be more understanding if you need to take more time off work to deal with doctor’s appointments or bad days. Employers may also be required to make reasonable adjustments to your work-place environment, for example making it easier for you to access the toilets by moving your desk or office.

Talking to friends, families and colleagues about your condition will also make it easier to manage your condition when you are out-and-about because you will feel less uncomfortable taking tables, and won’t feel a need to take them in secrecy, or discreetly.

If you would like to read more information on Living with Crohn’s disease, we recommend you have a look at the following guide produced by Crohn’s and Colitis UK.

Diet and Crohn’s Disease

There has been a lot of research into the effect of diet on Crohn’s disease. Overall, the results are that diet has a limited benefit in preventing disease progression.

It can, however, bring very significant benefits in terms of symptoms. It is also relatively easy to assess whether it is helping limit disease activity.

When is diet likely to be most useful

The diet hypothesis which was popularised by Professor John Hunter in Cambridge, amongst others, argues that certain foods increase the growth of bacteria in the gut. By reducing the burden of gut bacteria, the disease may come under control.

This applies most successfully in practice in patients with:

  • Disease limited to the end of the small bowel (terminal ileum)
  • Inflammatory disease in the absence of strictures or fistulae

Diet tends to work less well the further the disease is found from the end of the small bowel. Left sided colonic Crohn’s rarely responds to diet.

The steps in dietary treatment

The steps for dietary treatment include:

Reduce bacterial load

This can be done in two ways. The first is to give a course of antibiotics. Occasionally this alone can bring Crohn’s disease into a short-lasting remission. The second is to replace normal food with a pre-digested ‘elemetal’ diet for 2-3 weeks. As the liquid food-replacement has already been digested there is nothing for the bacteria in the gut to live on and they die. Once again, this tends to bring the patient into remission. This remission is likely to last only as long as the patient follows the diet.

Reintroduce foods that tend not to upset people

Certain foods are known to cause very limited upset. These tend to be foods that are low in fat and low in dietary fibre. The LOFFLEX (low fat, fibre limited) diet has a series of foods which can be reintroduced at the end of the elemental diet phase. Our experienced dietitian would be happy to support patients through managing the LOFFLEX diet process.

Test reintroduction of other foods

Other foods are known to aggravate symptoms in some people but not others. The approach is therefore to reintroduce foods one at a time and to watch out for any trigger of symptoms. The offending food is then removed from the diet

Avoid those foods which trigger symptoms

Many people find that they remain feeling very well for long periods of time when they are careful with their diet. Unfortunately, most NHS hospitals have limited access to dietary support services and so many people who could benefit from this approach to managing symptoms do not get an opportunity to do so. At the London Gastroenterology Centre, we have specialist dietitian support and would be happy to offer this to you.

Other Diets

Many other dietary approaches have been suggested for Crohn’s disease. One of the more successful ones is the ‘Specific Carbohydrate Diet’, also known as ‘Breaking the Vicious Cycle’. This diet avoids specific types of carbohydrates and probably works in a similar way to the diet outlined above. We have met quite a number of patients who have successfully used this diet. Our biggest reservation is that because it is so limited, it is difficult to continue long-term. As with all other dietary approaches, as soon as the diet is discontinued, the likelihood of diease relapse rises significantly.

Assessing the success of diet in Crohn’s disease

The last piece of the diet puzzle is to remember that an improvement in symptoms does not necessarily equate to bringing the disease under complete control. One of the simplest ways to assess disease activity is a non-invasive stool test called ‘faecal calprotectin’. This stool marker tends to rise when disease is active and fall when it is under control (in remission). We would be happy to offer this test to help you assess how your disease is faring, whether you are following a special diet or not. Please remember that no single test is 100% accurate. It needs to be used under supervision by a specialist in the disease.

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