Crohn’s Disease Risk Factors

What is Crohn’s Disease?

Crohn’s Disease is a type of inflammatory bowel disease (IBD). It is a chronic condition that causes inflammation that can affect any part of the gastrointestinal (GI) tract, running from the mouth to the anus.  However, the main affected areas are the lower end of the small bowel, known as the ileum and the beginning of the colon (part of the large bowel).^1,2

The inflammation caused by Crohn’s disease involves deeper layers of the bowel tissues, different from the inflammation caused by ulcerative colitis, which is limited to the mucosa (the inner lining of the GI tract) in the colon.³  It can also affect several separate areas with normal tissue in between them.^1,2

This disease is thought to be caused by cells of the immune system attacking cells of the digestive tract in your own body. This process triggers inflammation, causing Crohn's disease symptoms.⁴

Symptoms

As a result of the inflammation in Crohn’s disease, there is swelling of the digestive tract causing many GI symptoms, the main ones being:

• Diarrhoea – having recurrent episodes of loose stools can be a sign of Crohn’s disease.
• Cramping and abdominal pain – inflammation and bowel movements can result in pain.
• Weight loss – resulting from the nutrients not being well absorbed.
• Fatigue – a result of malnutrition caused by bowel inflammation.
• Blood in the stools – the inflammation process can result in bleeding, which can appear in the stools.
• Mouth sores – can be due to vitamin deficiencies (the exact reason for this is currently unknown)

There can also be other non-gastrointestinal symptoms, like problems with the joints, eyes, liver and skin, kidney stones, anaemia and delayed growth in children.^3,4,5

Causes of Crohn’s Disease

There is no known single cause for Crohn’s disease as of yet.  However, the consensus is that it is likely an immune-mediated response of the body triggered by environmental factors, affecting genetically susceptible people.^3,6

People who have relatives with Crohn’s disease were found to have a higher risk of developing the disease. Viruses and bacteria can trigger the inflammatory response to this disease. The immune system, which reacts to the invasion, tries to get rid of the microorganism, and this creates inflammation. In this condition specifically, the inflammatory response can be even triggered by the harmless “good” bacteria that live in our GI tract.^3,4,6

Risk factors

Diet

Some types of food can trigger the flare-up of symptoms and hence should be restricted or avoided after taking doctors' advice. 

Potential triggering foods:

• Food that is hard to digest, with insoluble fibres like whole nuts and grains, fruits (which are consumed with its skin), seeds and raw green vegetables.
• Alcohol and caffeinated drinks.
• Dairy products (containing lactose) like milk, cheese and cream.
• Food with a high amount of fat like butter, cream, fried and greasy food, margarine and coconut.
• Sugary foods like pastries, candies, cakes and juice.
• Extremely spicy food

Excess consumption of these foods causes bloating, diarrhoea and abdominal pain caused by intestinal cramping. It is highly recommended to avoid the specific food groups only after consultation with the physician, who will analyse the symptoms and give recommendations.^7,8

Stress

Although stress is not a direct cause of Crohn’s disease, it can trigger the symptoms of the condition, as chronic and acute stress can lead to abnormalities in the immune system and the inflammatory response.⁹ Chronic stress can also cause changes in the bowel microbes contributing to the inflammatory response of the immune system, which will lead to Crohn’s disease. Stress is also responsible for high levels of cortisol in the bloodstream leading to increased production of inflammatory chemicals called cytokines, which can be linked with worsening symptoms during Crohn’s exacerbations (flare-ups).¹⁰

Age

Crohn’s disease is generally diagnosed in teenagers and young adults because the symptoms start to appear even at a young age, which progresses to adulthood. However, there are instances where the symptoms only begin in adulthood. This happens because the causes of this disease are linked to genetic and immune factors, which are present at birth, and the triggering environmental exposures which can occur later in life.

Family history

People with a first-degree relative with Crohn's disease have a higher risk of presenting with the symptoms.

It is estimated that around 20% of the people who present with Crohn’s have a parent, sibling or child with the disease. Individuals with siblings with Crohn’s have a 17-35% increased chance of developing the disease. This corroborates that this condition is linked to genes.^3,6

Medication

The main medications associated with Crohn’s are antibiotics and painkillers (nonsteroidal anti-inflammatory drugs/NSAIDs), however, oral contraceptives and isotretinoin (used to treat acne) have also been related to it. Although the exact mechanism by which these medicines can trigger Crohn’s is still unclear, it is thought that NSAIDs can lead to inflammation of the bowel, making the disease and flare-ups worse.

Antibiotics contribute to Crohn’s since their use can change the normal spectrum of microorganisms in the bowel, leading to an overresponse of the immune system to new microorganisms.^3,6

Summary

Crohn’s disease is a type of Inflammatory Bowel disease (IBD) that can affect any part of the GI tract, from mouth to anus, affecting deeper layers of the GI tissue. The inflammation caused by this condition leads to symptoms like diarrhoea, abdominal pain, weight loss, fatigue, and blood in the stools and mouth sores.

Although the exact cause is still unidentified, it is thought to be a complex multifactorial disease that is genetically linked and immunomodulated. Several risk factors were identified as triggers, like certain types of food, stress and medicines like NSAIDs and antibiotics. This is a condition related to genes, so family history increases the risk, and it is usually diagnosed in teenagers and adults.