Crohn's Disease: Causes and Risk Factors

Scientists don't know exactly what causes Crohn's disease. However, they think it may involve a complex interaction of several factors, including genes, the immune system, and environmental triggers.

Crohn's disease tends to run in families and certain gene variations may put you at greater risk for developing it. An abnormal immune response may trigger chronic inflammation in your digestive tract that doesn't heal. In addition, certain medications geographic locations, and smoking, may all increase your risk.

Genes

It's taking time to pinpoint the exact nature of how Crohn’s disease may be inherited because while it has been known for some time that it runs in families, it was not exactly clear how that occurred.

Scientists have now identified more than 200 gene variations that may be involved in the development of Crohn’s disease.

The main genes associated with Crohn's are involved in immune function and help destroy digestive tract bacteria. However, most of these gene variations are thought to change the amount of gene activity and alter the immune system's response, causing it to attack healthy cells, leading to chronic inflammation. How these variations influence disease risk remains unknown, but they account for only a small percentage of the total Crohn's disease risk.

Studies show that between 5% and 20% of people with IBD have a close family member (e.g., parent or sibling) with the disease, increasing their risk of developing it. Also, Crohn's is most prevalent in people of Eastern European backgrounds, especially Jewish people of European descent.

However, it's thought that having the genes alone isn't enough to develop Crohn's disease and that there must also be one or more "triggers" that lead to the development of IBD. Because not everyone who carries the genes associated with Crohn’s disease eventually develops the condition, it’s understood that the cause includes more than a hereditary factor.

Autoimmune Reaction

Crohn’s disease is often described as an autoimmune condition. This is because the disease is thought to stem from a disruption in the immune system.

An autoimmune reaction occurs when your immune system attacks your healthy cells. For some reason unclear to scientists, the immune system may be triggered by bacteria or a virus to attack healthy parts of the digestive system. This causes inflammation, leading to the symptoms of Crohn's disease.

This is why it is often treated with medications that suppress the immune system. When the immune system is tamped down, it can decrease the effects that the overactivity is having on the digestive system.

The misfire in the immune system may come from a type of allergic response that causes the release of an abundance of eosinophils. Eosinophils are cells that fight off allergic responses. In doing so, they release toxic compounds. Research shows a relationship between people with Crohn’s disease and an excess amount of eosinophils in their blood and tissues.

Environmental Triggers

Even after the genetic and immune system factors are taken into account, there still may be more to the development of Crohn’s disease.

It’s currently unknown how many of these triggers exist or how they may interact with the other potential causes of Crohn’s disease. A few possible triggers include:

• Smoking: Cigarettes worsen Crohn’s disease and people with the disease are encouraged not to smoke. People who currently smoke or who have smoked in the past have an increased risk of developing Crohn’s disease.
• Nonsteroidal anti-inflammatory drugs (NSAIDs): These common painkillers may be associated with precipitating or worsening Crohn’s disease flare-ups. It’s unclear what their role (if any) may play in disease development.
• Antibiotics: There is some evidence that the use of antibiotics, especially early in life, could contribute to the development of Crohn’s disease. In some people, antibiotics are also associated with flare-ups of the disease.
• Contraceptive pill: There is some evidence that the contraceptive pill (birth control pill) may be associated with a small increase in the risk of developing Crohn’s disease.
• Geographic location: Crohn’s disease is more common in the industrialized world, particularly in North America and Western Europe, though the incidence is rising in Asia and South America.

Previous Gastrointestinal Infections

People with previous Salmonella or Campylobacter infections have an increased risk of IBD. These infections may trigger an immune response that changes the gut microbiome and leads to chronic inflammation.

A 2009 study followed 13,148 exposed people for up to 15 years. Those who had either infection were almost three times as likely to develop IBD over 15 years compared to those uninfected. The risk was highest the first year after infection but remained elevated for 15 years.

Debunking Common Myths

Researchers don’t know exactly why people develop Crohn’s disease, which has led to many incorrect ideas about what can cause it.

Diet and Stress

These were thought to play major roles in the development of Crohn’s disease, but do not cause IBD. Stress reduction and dietary modifications can be a part of treatment, but these lifestyle factors are neither causes nor cures for IBD.

Some research indicates that a high-fat diet (saturated fats, red meat, or animal fats) may increase the risk of developing IBD.

Several specialized diets may help alleviate symptoms and reduce flare-ups.

Some of these may include:

• Anti-Inflammatory Diet
• Crohn's Exclusion Diet
• Mediterranean Diet
• Specific Carbohydrate Diet
• Autoimmune Protocol Diet

Age

Although Crohn's disease is commonly diagnosed between the ages of 15 and 40 years, it can be diagnosed at any age, including children.

Summary

Although the exact cause of Crohn's disease remains unknown, researchers have suggested that genetics, autoimmune reactivity, and certain environmental triggers contribute to its development. Dietary and some lifestyle modifications may help alleviate symptoms but do not cause or cure this disease.

There is no cure for Crohn's disease but it can be managed by medication, lifestyle changes, and sometimes surgical interventions. Consult your healthcare provider to determine the best treatment plan for you.