Crohn’s Disease Overview


Crohn’s disease (CD) is a fairly common autoimmune, non-infectious, cause of diarrhea. It results from inflammation in the digestive tract, and the term inflammatory bowel disease encompasses CD and ulcerative colitis. Both diseases are caused by an overactive immune system that inappropriately attacks parts of the gastrointestinal (GI) tract.

What is Crohn’s Disease?

The gastrointestinal (digestive) tract/gut is a connected series of pipes and bag-like structures that starts at the mouth and ends at the anal opening. The mouth leads into the throat (oesophagus), which opens into the stomach, then into the small intestine, the large intestine and finally the rectum and the anus.

This tract digests and absorbs the food we eat, it also forms and excretes waste products from that food. To function properly, all of its segments need to be unobstructed to allow the absorption of nutrients and the free flow of food and food products.

CD is an autoimmune condition which results from an immune attack on the healthy gut lining in response to a trigger. The immune system erroneously identifies parts of the gut as foreign or harmful material that should be attacked, and goes ahead to do just that. This causes inflammation (swelling) in the gut and interferes with the functions described above - resulting in disease symptoms.

CD is mostly found in developed nations; it is however being seen more frequently now in developing countries - likely because increasing industrialisation provides suitable disease triggers.2


The disease course either waxes and wanes (with acute flares) or could be continuous and progressive. The symptoms of CD usually begin in early adolescence but can occur at any age. They include

  • Stomach pain/cramps
  • Diarrhea - this could contain blood
  • Unintended weight loss 
  • Fatigue
  • Fever
  • Loss of appetite
  • Painful ulcers in the mouth
  • Pain/difficulty when swallowing

Other organ systems outside of the gut could be affected by the inflammatory process in Crohn’s disease. This could cause the following symptoms:


The exact cause of Crohn’s disease is unknown. An interplay between genetics, the immune system and certain triggers like gut bacteria is thought to cause the disease.1

In people who are genetically predisposed, exposure of the immune system to a trigger leads to an inappropriate immune response.1

Risk factors

  • Genetics - genetically susceptible people are at much higher risk of developing CD. People with affected close relatives (parents, siblings) are more likely to develop it than the general population.3
  • Smoking - is believed to contribute to the inappropriate immune response in CD. Current and former smokers are at increased risk.4
  • Physical activity - the higher your rate of physical activity, the lower your risk of CD.5
  • Low fibre, high-fat diet - A diet that is high in fibre and low in fat has been shown to be protective against CD.6 
  • Gastrointestinal infections - no single infectious agent has been implicated as the cause of CD; infections of the GI tract by Salmonella and Campylobacter species have however been shown to increase the risk of the disease. It is thought that these, and possibly other pathogens (CD-associated microbes) can predispose to CD in genetically susceptible people.7,8
  • Drugs - there is an association between the use of some drugs and CD. These include certain antibiotics, non-steroidal anti-inflammatory drugs (NSAIDs), oral contraceptives and hormone replacement therapy.9,10,11
  • Obesity - this has also been shown to increase the risk of a CD diagnosis.12

Tips to reduce your risk of Crohn’s disease

You can reduce your risk of suffering Crohn’s disease and/or developing flares by making a few changes to your lifestyle. The following lifestyle factors have the greatest impact on your risk of Crohn's disease. We will also look at what you can do to reduce your risk from today.


It has been shown that a long-term high intake of fibre - especially from fruits and vegetables - is protective against CD.6 A balanced and healthy diet can provide the right amount of fibre to protect not just against CD, but against heart disease as well.

Quit smoking

Smoking is one of the strongest risk factors for CD; it also increases the risk of disease flares. The longer the time you stay away from smoking, the lower your risk of flares. Quitting smoking, therefore, has the potential to improve the quality of life in CD patients. Speak to your healthcare provider about the resources available to help you quit.

Physical activity

Regular exercise decreases your risk of getting CD;  it can also decrease disease flares in people who have it.5 


Obesity is a risk factor for CD. It also increases the risk of flares in people diagnosed with the disease. Consequently, it is important to maintain a normal weight.12


Alcohol misuse increases the risk of flares and worsens outcomes in people with CD .13 Support is available if you need help cutting back.


Both poor sleep and inadequate amounts of sleep have been linked to worse outcomes in patients with CD. If you suffer from CD, it is therefore important that you get adequate amounts of good quality sleep. Practice good sleep hygiene to ensure you get as much as you need.10

Mental health

Mental health issues like anxiety and depression are common in patients with CD. As there exists a close interaction between psychological and physical health, addressing them is believed to improve the quality of life of patients suffering from CD. 13 Speak to your healthcare provider about getting the help you need! Support is also available from Crohn's and colitis foundation.


Keeping your emotional health balanced is necessary for your physical health. Self-care is important for overall good health.

There are recurring themes in most wellness pitches: a balanced diet, adequate amounts of physical exercise and sleep, abstinence from smoking, low alcohol consumption and maintenance of good psychological health. These are fundamental not just for reducing risk factors of developing  CD and/or its flares - they are needed for overall good health!


Crohn’s disease is a potentially debilitating condition which is caused by an inflammation of any part of the GI tract. The trigger is unknown, but an interaction between genetic and environmental factors is believed to be responsible. A healthy lifestyle can decrease CD risk and/or improve the quality of life in people living with Crohn's disease.

Diagnostic testing

At Klarity we use the latest technology when it comes to diagnostic testing. Our home blood tests give you health insights and personalized recommendations. Find out which test you should take.


  1. Goethel A, Croitoru K, Philpott DJ. The interplay between microbes and the immune response in inflammatory bowel disease. J Physiol. 2018 Sep;596(17):3869-3882. 
  2. GBD 2017 Inflammatory Bowel Disease Collaborators. The global, regional, and national burden of inflammatory bowel disease in 195 countries and territories, 1990-2017: a systematic analysis for the Global Burden of Disease Study 2017. Lancet Gastroenterol Hepatol. 2020 Jan;5(1):17-30. Available from: 
  3. Halfvarson J, Bodin L, Tysk C, Lindberg E, Järnerot G. Inflammatory bowel disease in a Swedish twin cohort: a long-term follow-up of concordance and clinical characteristics. Gastroenterology. 2003 Jun;124(7):1767-73.  Available from:
  4. Higuchi LM, Khalili H, Chan AT, Richter JM, Bousvaros A, Fuchs CS. A prospective study of cigarette smoking and the risk of inflammatory bowel disease in women. Am J Gastroenterol. 2012 Sep;107(9):1399-406.  Available from:
  5. Khalili H, Ananthakrishnan AN, Konijeti GG, Liao X, Higuchi LM, Fuchs CS, et al. Physical activity and risk of inflammatory bowel disease: prospective study from the Nurses' Health Study cohorts. BMJ. 2013 Nov 14;347:f6633.. Available from: 
  6. Ananthakrishnan AN, Khalili H, Konijeti GG, Higuchi LM, de Silva P, Korzenik JR, et al. A prospective study of long-term intake of dietary fiber and risk of Crohn's disease and ulcerative colitis. Gastroenterology. 2013 Nov;145(5):970-7.Available from:
  7. Gradel KO, Nielsen HL, Schønheyder HC, Ejlertsen T, Kristensen B, Nielsen H. Increased short- and long-term risk of inflammatory bowel disease after salmonella or campylobacter gastroenteritis. Gastroenterology. 2009 Aug;137(2):495-501. Available from:
  8. Chassaing B, Darfeuille-Michaud A. The commensal microbiota and enteropathogens in the pathogenesis of inflammatory bowel diseases. Gastroenterology. 2011 May;140(6):1720-28.  Available from:
  9. Nguyen LH, Örtqvist AK, Cao Y, Simon TG, Roelstraete B, Song M, et al. Antibiotic use and the development of inflammatory bowel disease: a national case-control study in Sweden. Lancet Gastroenterol Hepatol. 2020 Nov;5(11):986–95. 
  10. Troelsen FS, Jick S. Antibiotic Use in Childhood and Adolescence and Risk of Inflammatory Bowel Disease: A Case-Control Study in the UK Clinical Practice Research Datalink. Inflamm Bowel Dis. 2020 Feb 11;26(3):440-447.Available from:
  11. Ananthakrishnan AN, Higuchi LM, Huang ES, Khalili H, Richter JM, Fuchs CS, et al. Aspirin, nonsteroidal anti-inflammatory drug use, and risk for Crohn disease and ulcerative colitis: a cohort study. Ann Intern Med. 2012 Mar 6;156(5):350-9. Available from: 
  12. Chan SSM, Chen Y, Casey K, Olen O, Ludvigsson JF, Carbonnel F, et al. Obesity is associated with increased risk of crohn’s disease, but not ulcerative colitis: a pooled analysis of five prospective cohort studies. Clinical Gastroenterology and Hepatology. 2022 May 1 ;20(5):1048–58. Available from:
  13. Piovezani Ramos G, Kane S. Alcohol use in patients with inflammatory bowel disease. Gastroenterol Hepatol (N Y). 2021 May;17(5):211–25. Available from: presents all health information in line with our terms and conditions. It is essential to understand that the medical information available on our platform is not intended to substitute the relationship between a patient and their physician or doctor, as well as any medical guidance they offer. Always consult with a healthcare professional before making any decisions based on the information found on our website.
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