Digestive Disorders > IBD

What is Chronic Inflammatory Bowel Disease (IBD)?

Dr. med. Andre Sommer

Dr. med. Andre Sommer

The abbreviation “IBD” stands for “inflammatory bowel disease.” Symptoms usually recur again and again, so it is considered a chronic disease. All forms of IBD affect the intestine and can be accompanied by similar symptoms, but it is not always only the intestine that is affected.

What diseases are considered inflammatory bowel diseases?

Crohn's disease and ulcerative colitis are the two main inflammatory bowel diseases. If inflammation in the large intestine cannot be clearly assigned to either of these, it is referred to as an unclassified IBD (IBD-U) or colitis indeterminate. Chronic inflammation of the intestinal mucosa is present in both ulcerative colitis and Crohn's disease, but the exact location of the inflammation and the distribution pattern differ between the two diseases. Chronic inflammatory bowel diseases are not contagious.

What are the symptoms of IBD?

Chronic or relapsing diarrhea can be an indication of IBD. With ulcerative colitis, bloody-slimy diarrhea often occurs; this is rare with Crohn's disease. However, with Crohn's disease, diarrhea is often accompanied by severe abdominal pain. In some cases, constipation can alternate with diarrhea.

How common is IBD?

According to an estimate from 2013, about 0.3 percent of the population was affected by inflammatory bowel disease. The number of new cases in Western industrialized nations is steadily increasing. Although the exact origins are still unclear, IBD is seen as a so-called “disease of civilization,” which refers to diseases that are related to lifestyle in industrialized nations.

What to do if IBD is suspected?

Rarely does IBD begin with an acute episode (i.e. a phase with severe symptoms). As a rule, the beginning is slow. Persistent or recurring (chronic) diarrheal diseases should always be clarified by a doctor.

Various examinations are carried out to rule out or confirm IBD. The first steps can be taken by a general practitioner. If the patient continues to suspect IBD, they are referred to a gastroenterologist. In children, these examinations should be carried out in a specialized center with trained children's gastroenterologists, since the metabolism of a child differs from that of an adult.

  1. Examination by a general practitioner:
  2. Detailed survey on medical history (anamnesis)
  3. Physical examination
  4. Laboratory examination: Inflammation markers in the blood and stool to rule out infections
  5. Examination by the gastroenterologist:
  6. Examination of the intestine using a camera from the inside (endoscopy)
  7. Tissue removal of the intestinal mucosa for tissue examination (biopsy) from the end of the small intestine (ileum), the large intestine (colon) and the rectum
  8. Imaging examination of the small intestine: Ultrasound (sonography), X-ray, possibly magnetic resonance imaging (MRI)

There are many causes of diarrhea symptoms. In addition to food intolerance, allergies or acute gastrointestinal infections, irritable bowel syndrome or IBD can also be present. Therefore, a comprehensive diagnostic examination with a doctor specializing in the stomach and intestines (gastroenterologist) may be advisable if symptoms persist.

Can children get IBD?

Crohn’s disease occurs most commonly between the ages of 15 and 35, while ulcerative colitis occurs most commonly between the ages of 20 and 35. But you can still develop a chronic inflammatory bowel disease even in infancy. The incidence of illness among children under the age of 10 is even increasing.

When should a child be examined for IBD?

Children and adolescents should be examined medically if they suspect IBD. A clue here is if the person complains about the following symptoms for four weeks in a row or several times over the course of six months (more than two episodes).

Symptoms that indicate IBD in children:

  • Acute stomach pain
  • Diarrhea
  • Weight loss
  • Malnutrition
  • Lack of appetite
  • Blood in stool (rectal bleeding)
  • Fatigue and pallor due to anemia (e.g. when there is a lack of iron)
  • Decrease in performance
  • Fever
  • Delayed onset of puberty
  • Fissures (tears) and fistulas (tube-like connections to other organs or to the body surface) in the anal area

The symptoms mentioned are particularly likely to occur with Crohn's disease. Ulcerative colitis is often only accompanied by bloody diarrhea.


Only about a quarter of children with IBD show the classic symptoms of abdominal pain, diarrhea, and weight loss.

What causes IBD?

The causes of IBD are currently unknown. However, first-degree relatives (i.e. children) of people with IBD have a four to eight-fold increased risk of developing it. Some altered (mutated) genes have already been identified alongside Crohn's disease, so there is a so-called family disposition. Experts believe that with these gene mutations (e.g. the NOD2 gene) the immune system cannot effectively fight the against invading bacteria. This allows the bacteria to stay in the intestine and penetrate the intestinal wall. When this occurs, the immune response is exaggerated and the intestinal mucosa becomes inflamed, the stomach hurts, and diarrhea occurs.

During the course of IBD, pus accumulations (abscesses) and fistulas can form due to the excessive inflammatory reaction. In the long term, IBD increases the risk of pathological vascular deposits (arteriosclerosis) and events in the arteries. Chronic systemic inflammation is believed to be the cause.

Smoking is unhealthy and increases the risk of cardiovascular disease and lung and other cancers. Smoking is also a risk factor for Crohn's disease and leads to a more severe course of the disease. With ulcerative colitis, nicotine is considered a protective factor. However, ulcerative colitis patients also suffer from tobacco-dependent diseases such as heart and vascular diseases or cancer.

Is only the intestine affected?

IBD can also lead to inflammation and discomfort outside the intestine, and these so-called “extraintestinal symptoms” are common. If IBD results in painful joint inflammation, it is referred to as enteropathic arthritis (EA). A distinction is made between two types:

Type 1

  • Occurs acutely as a flare-up and often affects the knee joints
  • In 90 percent of people, the complaints disappear on their own within six months (spontaneous remission)

Type 2

  • Chronic course with frequent relapses
  • Multiple finger joints are affected by the painful inflammation

In addition to the joints, extraintestinal symptoms of IBD are found primarily with the skin, eyes, and bile duct.

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What role does nutrition play in IBD?

The role of nutrition in the development and treatment of IBD is a controversial topic. It is clear both that the risk of malnutrition is increased in IBD patients and that this worsens the prognosis. Therefore, malnutrition should always be counteracted.

In addition to specific nutritional advice, supplements of micronutrients can also be used if necessary (calcium, vitamin D, folic acid, vitamin B12, iron, and zinc). The use of probiotics (preparations with health-promoting bacterial cultures) can support ulcerative colitis during the remission phase (the phase with little or no disease activity).

In contrast, with Crohn's disease there appears to be no additional positive effect. Since people with IBD often have intolerances to certain foods, these should be clarified. They can cause and worsen symptoms. Since the influence of eating habits on IBD has not yet been sufficiently clarified, there are no special nutritional recommendations.

But this is true in general: With an acute episode, the diet should be particularly gentle on the intestines and therefore low in fiber. In the symptom-free phase, swelling substances such as psyllium should be on the menu. Someone who is affected can then also eat a higher-fiber diet. However, they should still avoid poorly tolerated foods.

What to do if you suspect a food intolerance?

The tolerance of different foods is very individual with IBD patients. You can find out which foods and which forms of preparation cause symptoms by keeping a nutrition and symptom diary. Over time, you can determine patterns and relationships between certain foods and symptoms.

How is IBD treated?

There is as of yet no cure for Crohn's disease or ulcerative colitis. Once people have experienced the disease, IBD accompanies them for a lifetime. One exception is the surgical removal of the colon with ulcerative colitis when there is no alternative treatment, but this is an extensive operation that can also have significant side effects.

With both diseases, drug therapy aims to reduce inflammatory activity during relapses, depending on the severity of the inflammatory reaction. During the symptom-free phase (remission), an attempt is made to stabilize the disease with medication. The aim is to improve the quality of life and to maintain bowel function.

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Forbes A, Escher J, Hébuterne X, et al. ESPEN guideline: Clinical nutrition in inflammatory bowel disease. Clinical Nutrition. 2017;36(2):321-347. doi:10.1016/j.clnu.2016.12.027

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Dr. med. Andre Sommer

Dr. med. Andre Sommer

I’m André, a medical doctor from Berlin. Together with a team of medical doctors, nutritionists and data scientists we empower people to understand digestive issues with our app Cara.

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