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What is Crohn’s disease?

Crohns Disease

Inflammatory bowel disease (IBD) is the term given for a group of disorders where the intestines become inflamed. One of the two major types of IBD is Crohn’s disease (the other is ulcerative colitis).

Unlike ulcerative colitis – where the inflammation is limited to the colon (large intestine) – the inflammation and ulceration associated with Crohn’s disease can affect any part of the digestive system, from the mouth to the anus (though it’s most likely to develop in the last part of the small intestine, called the ileum, or the colon).

Named after a New York doctor called Burrill Crohn who reported a number of cases in 1932, it’s a life-long condition that can cause relapses or flare-ups of symptoms interspersed with periods of good health (remission).

According to Patient, Crohn’s disease is diagnosed in about one in every 10,000 people each year in this country, and around 145 in 100,000 people in the UK have it. It can develop at any age, but the most common stage for Crohn’s disease to start is between the ages of 15 and 30. It’s also more common in smokers than non-smokers, and if someone in your family has Crohn’s disease you’re also more likely to develop it. It’s also more common in people who’ve had their appendix taken out during the first five years following the operation (i).

Common symptoms

Symptoms vary from one person to the next – for some, flare-ups can be mild but for others they can be more severe. Here are some of the most common things you may experience:

  • Diarrhoea and abdominal pain

  • Tiredness and fatigue

  • Weight loss and loss of appetite

  • Mouth ulcers

  • General feelings of being unwell

Some of these symptoms are caused by the fact that your body may not be able to digest food and absorb nutrients from food. You may also lose blood with diarrhoea, which – along with not being able to fully absorbing the nutrients from your food – can cause anaemia.

Meanwhile, there are different types of Crohn’s disease that are categorised according to the part or parts of the digestive system (or gut) affected. Crohn’s colitis, for instance, is the type of Crohn’s disease that affects the colon, whereas ileal Crohn’s is when there’s inflammation in the ileum. Gastroduodenal Crohn’s disease affects the stomach and duodenum (first part of the small intestine), while jejunoileitis affects the jejunum, the upper half of the small intestine, and perianal Crohn’s affects the anus.

Depending on which type of Crohn’s disease you have – in other words, which part of your digestive system is affected – you may experience different symptoms. For instance, the main symptom of Crohn’s colitis is often blood-stained diarrhoea, while perianal Crohn’s can cause fissures (tears in the lining of the anal canal) and haemorrhoids.

What causes it?

Nobody knows exactly why some people develop Crohn’s disease. Experts believe it may be the result of a mix of different factors. Your genes may be partly responsible, since around three in 20 people with Crohn’s disease have a close relative who also has it (i). White people of European descent, particularly those who are descended from Ashkenazi Jews, are also more likely to develop Crohn’s (ii). Another theory is that it may have something to do with a problem with your immune system (i).

Meanwhile various triggers that have been suggested include smoking, diet, stress, viruses and bacteria, though none of these has been proven to cause Crohn’s (ii). There may also be environmental factors involved, since Crohn’s is more common in westernised countries than in less developed parts of the world (iii).

Crohn’s disease complications

If you have Crohn’s disease, you may have a higher risk of developing other health problems, both in the digestive system and in other parts of your body.

Complications that occur in the gut include strictures, perforations and fistulas:

  • Strictures are narrow sections of the bowel caused by scar tissue formed by inflammation. These can cause severe abdominal pain, nausea, vomiting and constipation, as food may not be able to pass through the bowel easily or at all.

  • Perforations within the bowel can happen when a stricture blocks the bowel badly. If there’s a perforation in the bowel, the contents can leak through the hole and form an abscess, causing pain and a high temperature.

  • Fistulas are tunnels or passageways that can develop from abscesses or when inflammation spreads through the bowel wall and starts to affect other tissues. If you have a small fistula, it doesn’t usually cause any symptoms. But larger fistulas can become infected, causing symptoms such as pain and a high temperature.

Besides these complications, Crohn’s can also increase your risk of other medical conditions. Here’s how it may affect other parts of your body:


According to the charity Crohn’s And Colitis UK, one in seven people with Crohn’s have a skin condition called erythema nodosum, which causes painful red swellings, usually on the legs, during a flare-up (ii). Less commonly, some people with Crohn’s have a condition called pyoderma gangrenosum, which causes small blisters anywhere on the body (most commonly the shins) that become painful ulcers.


Up to one in three people with inflammatory bowel disease also have joint problems such as arthritis, including those with Crohn’s colitis (Crohn’s disease in the colon) (iv). A few are affected by a type of arthritis called ankylosing spondylitis, which causes inflammation in the joints in the spine and pelvis.


Osteoporosis – thinning of the bones – can develop if you have Crohn’s, because your digestive system may not be absorbing the nutrients your bones need from the food you eat. Taking steroid medication – the medical treatment for Crohn’s – may also affect your bone density.


Studies show that from four to 10 per cent of people with Crohn’s are affected by a condition that makes their eyes red, sore and inflamed (the most common is episcleritis) (v).


An estimated one in three people with Crohn’s develops gallstones (i).


A disease called primary sclerosing cholangitis (PSC) is a rare complication of Crohn’s disease, affecting up to one in 50 people who have Crohn’s (i). This affects the bile ducts inside and outside the liver, and can lead to jaundice and eventually liver damage.


Anaemia caused by a lack of iron, vitamin B12 or folic acid can be common in people with inflammatory bowel disease because of the way it reduces your digestive system’s ability to absorb nutrients from food. People with Crohn’s are also thought to be twice as likely to develop blood clots in their veins, including deep vein thrombosis (DVT) in their legs (i).

Diet and Crohn’s disease

Since Crohn’s disease affects the digestive system, you may assume there’s a link between the condition and diet. Yet despite a wide range of food and nutrients having been studied in relation to the development of Crohn’s, there’s no clear evidence that diet is a direct cause.

On the other hand, some researchers believe diet could have something to do with Crohn’s disease because of the fact that it’s more prevalent in western countries than in non-western parts of the world. This has led some to suggest that Crohn’s and other forms of inflammatory bowel disease (IBD) may be linked with the typical western diet, which is high in fats and sugars and low in fruit, vegetables and fibre (vi).

It’s also true that some people with Crohn’s find certain foods trigger their symptoms or make them worse. The charity Crohn’s & Colitis UK recommends looking at your diet and keeping a food diary to see if you notice a link between what you eat and your symptom flare-ups, as cutting out any trigger foods could help.

Some people, for instance, may find one or more of the following may trigger their Crohn’s symptoms:

  • Nuts and seeds

  • Raw fruit/vegetables

  • Butter/margarine and fatty foods

  • Coffee, tea, hot chocolate

  • Fizzy drinks

  • Red meat

  • Spicy foods

  • High-fibre foods

  • Beans and lentils

However, before making any changes to your diet, you should get advice from your doctor or from a qualified dietician to make sure your diet is as healthy and well balanced as possible (the total elimination of entire food types – such as grains or sugars – isn’t usually recommended).

You could also try eating smaller, more frequent meals instead of three larger meals each day, as this may help to improve your symptoms.

Liquid food diet

Some Crohn’s experts also believe a dietary treatment where you have a liquid diet for a number of weeks instead of your usual food can be effective. According to Crohn’s & Colitis UK, these liquid feeds contain all the essential nutrients in a simple form that your body can absorb with little or no digestion (vi). This helps because it gives your body a chance to recover without you having to miss out on the nutrients you need.

Called enteral nutrition (or an elemental or polymeric diet), it’s widely used for children with Crohn’s disease. But there’s less evidence for the effectiveness of this approach for adults. Some people, however, may prefer a dietary treatment to conventional drug treatments, despite it being less effective.

There are different types of liquid feed available – your doctor or dietician will decide which would be most suitable for you.

Treatments for Crohn’s disease

Medical treatments for Crohn’s aim to reduce the disease’s symptoms.

Steroid medication is usually the first treatment your doctor will want you to try. This is designed to help to reduce inflammation, and you may receive the treatment as tablets or injections. Steroids are effective, but most have significant side effects, such as weight gain, thinning and weakening of the bones, swelling of the face and a reduced resistance to infections (milder steroids are available that have fewer side effects, but these are less effective at reducing the symptoms of Crohn’s).

Immunosuppressant medication can also be used in combination with steroids if you have two or more flare-ups during a year. Again, there are several side effects to be aware of, including tiredness and weakness, liver problems, nausea and vomiting, pancreatitis and a reduced resistance to infections. It’s also worth knowing that one particular type of immunosuppressant medication called methotrexate shouldn’t be taken for at least six months if you’re trying for a baby, as it’s known to cause birth defects.

Biological therapies are medicines used for people experiencing severe Crohn’s symptoms, who are in poor general health, or for those whose symptoms haven’t improved after taking steroid and immunosuppressant medications. These medicines work by targeting a protein that’s thought to cause the inflammation associated with Crohn’s.

Natural support for Crohn’s disease

If you have Crohn’s disease, it’s commonly accepted that you may not be able to absorb all the nutrients you need from the food you eat. This explains why many natural health practitioners recommend adding more nutrients to your diet in the form of nutritional supplements.


Take magnesium, for example. It is one of the essential minerals your body needs to function normally. But an article published in the Canadian Medical Association Journal claims magnesium deficiency is common among people with Crohn’s disease, particularly those who’ve part of their ileum removed (vii). Another study suggests magnesium is one of the important nutrients needed to manage Crohn’s disease (viii).

Magnesium may also be useful to help counteract the stress caused by having Crohn’s disease (some experts believe magnesium levels may be depleted by stress (ix)). It may also help if stress is making it difficult for you to sleep properly (x).


Another nutritional supplement that could help with stress is the amino acid theanine (L-theanine). Indeed, there’s evidence to suggest theanine may help reduce stress without causing drowsiness (xi).


Other nutrients you may be missing if you have Crohn’s disease include calcium (particularly if you take steroid medication), vitamin D, iron, potassium and zinc. It may therefore be a good idea to take a high-strength multivitamin and mineral supplement that contains sufficient levels of these – and other – nutrients to help boost your levels.

Vitamin B

You may also want to consider taking a vitamin B complex supplement that contains good levels of vitamin B12 and folic acid, as deficiencies in both nutrients have been linked with Crohn’s (xii). Vitamin B12 deficiency may also be a problem if you’ve had intestinal surgery, while your absorption of folic acid may be affected if you’re taking certain medications used in the treatment of Crohn’s.

Fish Oil

Finally, a good-quality, high-strength fish oil supplement may help, as the omega-3 fatty acids found in oily fish are thought to help reduce inflammation (xiii). Experts writing in the Annals of Gastroenterology journal also note that several studies show omega-3 fatty acids lead to the production of compounds in the body that weaken inflammatory processes, which may help people with inflammatory bowel disease (xiv).

Fish oil supplements may be useful if you cannot or don’t want to eat regular portions of oily fish, including salmon, pilchards, sardines, mackerel and fresh tuna. You can also benefit from an omega-3 supplement if you’re a vegetarian or vegan, thanks to the availability of supplements that contain the natural triglyceride (TG) form of omega-3, which is sourced from plant organisms called microalgae rather than fish oils.

Managing your Crohn’s disease can be a little easier when you know the right ways to support your body. For even more advice on a range of other health conditions, simply visit our 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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