Health experts are still unsure on what exactly causes Crohn’s disease, although there are several theories on this subject. Most believe that this illness is usually caused by any (or a combination of) these factors:1
• Having an abnormal immune system. The immune system serves as the body’s protection against infections from bacteria and viruses. However, 80 percent of your immune system is located in your gut, which, in turn, is home to different types of good and bad bacteria.
In a healthy person, the immune system recognizes these bacteria — it allows the good bacteria to thrive, while killing off the harmful ones.
But when something disrupts the immune system, it fails to recognize these bacteria and instead sends a special protein known as tumor necrosis factor-alpha (TNF-alpha).
This protein kills all the bacteria — whether good or bad. Once this happens, white blood cells build up in the gut lining, which then triggers inflammation, ulcerations, and bowel injury.2
• Heredity. Genetics may play a role in the development of Crohn’s disease, as 200 different genes that are more common in people with this illness have been identified. It’s also said that having a particular genetic makeup can affect the immune system’s reaction.
People who are predisposed to this illness may have inherited some type of defective gene/s that can lead to the abnormal immune reaction.3 In 2009, researchers have discovered DNA variations in a gene that can increase a person’s susceptibility to developing Crohn's disease.
They pinpointed DNA sequence variants in a gene region called NLRP3, which are thought to be associated with increased susceptibility to Crohn's disease. These findings were published in the journal Nature Genetics.4
Crohn’s disease can be inherited — about 3 in 20 people affected by it have a close relative who has or had this illness. If you have an identical twin with Crohn’s then you actually have a 70 percent chance of having it as well.5
• Acquiring a new or having a previous bacterial infection. Some genetically susceptible individuals who had a previous infection during their childhood may actually be at risk of this illness, as the infection may trigger an abnormal immune response.
• Using nonsteroidal anti-inflammatory medications (NSAIDs). Taking these prescription drugs can lead to inflammation that may trigger or worsen Crohn’s disease. These include ibuprofen, naproxen sodium, and diclofenac sodium. According to studies, these flares can occur within a week of taking the NSAIDs regularly.
• Smoking. This is probably the most controllable cause of this chronic illness. Smokers are twice as likely to develop Crohn’s disease compared to non-smokers, and they experience more severe symptoms that usually end up requiring surgery.
• Diet. While there’s no solid evidence claiming that certain foods plays a role in the development of Crohn’s disease, there are speculations saying that a diet that’s generally high in refined sugars can trigger this illness. This isn’t surprising, considering that refined sugars like fructose trigger insulin and leptin resistance, which are hallmark symptoms of inflammation.
Processed foods, particularly those loaded with emulsifiers, may play a role in the development of Crohn’s disease. Scientists found that these food additives may break down the mucosal lining of your gut, increasing your risk of this illness. This is because the mucosal lining contains bacteriophages, which are viruses that destroy harmful bacteria in your gut, helping keep you healthy.
Other lifestyle factors, such as increased exposure to germ-free environments, may also play a factor in the development of this disease. One theory, called the hygiene hypothesis, suggests that children who grow up in increasingly germ-free environments may have immune systems that are not fully developed.