Inflammatory bowel disease (IBD) is a chronic inflammatory condition affecting the digestive tract. There are several types of inflammatory bowel disease, but most common among these are Crohn’s disease and ulcerative colitis. Here are the major inflammatory bowel disease causes, symptoms, and treatments that can help.

What is inflammatory bowel disease? 

Inflammatory bowel disease, or IBD, is an autoimmune condition affecting the digestive tract. In individuals with inflammatory bowel disease, the immune system mistakenly attacks the bowels, causing inflammation. The inflammation can occur in all or part of the digestive tract.

There are two main types of inflammatory bowel disease: Crohn’s disease and ulcerative colitis. The symptoms will vary depending on which specific type it is. There are additional types, but ulcerative colitis and Crohn’s disease are the most common.

Inflammatory bowel disease symptoms

Symptoms of inflammatory bowel disease can vary, depending on the location and severity of inflammation. The traditional symptoms of inflammatory bowel disease include:

  • Diarrhea
  • Pain and cramping
  • Blood in the stool
  • Fevers
  • Weight loss
  • Low grade fever
  • Fatigue
  • Joints, skin, and eye changes

Additionally, the two most widespread types of inflammatory bowel disease can have slightly different symptoms. For instance, Crohn’s disease can result in nausea, vomiting, and bloating, indicative of intestinal blockages. Ulcerative colitis can, in its most rare and severe form, cause acute pain, profuse diarrhea, and inability to eat.

Unsurprisingly, a reduction in appetite can often happen in people with inflammatory bowel disease. Not only does the reduced appetite potentially make it difficult to eat enough, but inflammatory bowel disease can also make it difficult for the body to properly digest and absorb nutrients. Because of this, weight loss, malnutrition, or vitamin deficiencies are fairly common among people with this disease.

It’s also possible for the symptoms of inflammatory bowel disease to change over time. During flare-ups, the symptoms might be severe, but it’s also possible for the disease to go into remission. When remission occurs, there may no symptoms at all for a period of time.

Crohn’s disease

Crohn’s disease can involve any part of the digestive tract.

Most often, though, the end of the small bowel and beginning of the large bowel are involved. Additionally, the inflammation can penetrate through all the layers of the intestines. Patches of healthy bowel are possible between the patches of diseased bowel.

If the inflammation associated with Crohn’s disease affects mainly the bowel wall, the bowel can narrow due to inflammation or scarring, or a combination of the two (called fibrostenosis or stenosis). If the bowel becomes too narrowed, it can become blocked. As a result of blockages, cramping, vomiting, and bloating can all occur. Ulcers can also occur as a result of these blockages.

When Crohn’s disease inflammation penetrates more deeply into the layers of the bowel, it can lead to ulcer formation. If the ulcers get deep, they can become tracts called fistulas, creating a passage between two spaces where there isn’t supposed to be one.

Ulcerative colitis

Usually, ulcerative colitis mostly affects the rectum and the upper part of the large intestine.

With this type of inflammatory bowel disease, the lining of the large intestine (also called the colon) and the rectum are afflicted with long-lasting inflammation and ulcers. Although ulcerative colitis is not associated with blockages, stenosis, or fistulas, this type of inflammatory bowel disease can be significantly more severe than Crohn’s disease.

A classification system is utilized to group together the different types of ulcerative colitis. The five classifications are determined by the location and severity of symptoms, although all five classifications still fall under the umbrella of ulcerative colitis. The five types of ulcerative colitis, in order from most mild to most severe, are:

  • Ulcerative proctitis, which affects the rectum
  • Proctosigmoiditis, which affects the rectum and the lower end of the colon (also called the sigmoid)
  • Left-sided colitis, which affects the rectum, the lower end of the colon, and the descending colon
  • Pancolitis, which can affect all of the colon
  • Acute severe ulcerative colitis, which affects all of the colon

The symptoms can range from rectal bleeding only, as in ulcerative proctitis, to the acute pain, profuse diarrhea, fever, bleeding, and inability to eat associated with acute severe ulcerative colitis.

What Are Common Inflammatory Bowel Disease Causes? |

Inflammatory bowel disease in children

It’s estimated that around 1.6 million people in the United States are living with some form of inflammatory bowel disease. Of these people, one in ten is below the age of 18. One in four was diagnosed before age 20. When inflammatory bowel disease occurs in children, it’s sometimes referred to as pediatric IBD.

Not all of the symptoms of inflammatory bowel disease in children are the same as in adults. The Pediatric IBD Consortium explains, stating:

“Children with Pedi IBD are not small adults with IBD. Children with Pedi IBD often come to their doctors with different symptoms than adults with IBD. One of the most important issues that need to be addressed specifically in children with IBD is a lack of growth. Because childhood is a time when nutrition has the most significant impact on growth, if a child is not getting enough calories and nutrients, they will not grow and develop at a normal and healthy rate.”

Even if a child is diagnosed with inflammatory bowel disease, it can be difficult to differentiate between Crohn’s disease and ulcerative colitis. This is particularly true if the child is less than five years old. In this case, he or she may be diagnosed with indeterminate colitis.

Risks of inflammatory bowel disease in children

Children with inflammatory bowel disease may face slightly different challenges than adults with the disease. Lack of growth can be a serious issue in children with inflammatory bowel disease. In fact, one in three children with Crohn’s disease and one in ten children with ulcerative colitis fail to reach their expected adult height because of their inflammatory bowel disease.

Also, children with inflammatory bowel disease are at risk of low bone mineral density, which significantly increases the risk of osteoporosis and fractures later in life. In a study of 144 children with inflammatory bowel disease between the ages of six and 19, one-half of the study participants had low bone mineral density. Another study found that as compared to children without inflammatory bowel disease, children with the disease have aerobic fitness levels that are 25% lower and muscle function that is 10% lower.

What are the major inflammatory bowel disease causes?

Recent research suggests that a combination of factors contribute to someone developing inflammatory bowel disease. The major inflammatory bowel disease causes could include:

  • Genetics
  • Relation to other inflammatory conditions
  • Gut bacteria and viruses


The first, and most unchangeable, factor that contributes to inflammatory bowel disease is genetics. In studies of DNA samples from Europeans, over 160 genome variants have been identified as associated with an increased risk of inflammatory bowel disease. Recently, scientists have added a pool of DNA samples from people of East Asian, Iranian, or Indian descent. Thanks to the increased size of the DNA pool, an additional 38 regions of the genome were identified as influencing an individual’s susceptibility to inflammatory bowel disease.

Aside from the additional identified genomes, there were also a few differences in genetic susceptibility to inflammatory bowel disease. These differences in genetic susceptibility could be because of small differences in genome structure or environment.

Two of these differences are explained in an article published by the Wellcome Trust Sanger Institute:

“There are genetic variants in a gene called NOD2 which increase risk of IBD in Europeans that are simply not present in Asian populations… At another gene, called TNFSF15, the IBD risk-increasing variants are at a similar frequency in both Europeans and East Asians, but the variants seem to have a much stronger effect on disease risk in East Asia.”

Other researchers found a gene that’s responsible for regulating a signaling molecule. Elevated amounts of this signaling molecule, called TNF, are associated with inflammatory bowel disease. In experiments with zebra fish, researchers found that a specific gene (uhrf1) acts as a “handbrake” on TNF production. When this gene is “turned off,” or inactivated, TNF production increases, as does the risk of inflammatory bowel disease. These researchers are now searching for ways to find similarly-functioning genes in humans.

Relation to other inflammatory conditions 

Additionally, another study identified a higher incidence of inflammatory bowel disease among people who have inflammatory lung conditions, such as asthma or chronic obstructive pulmonary disease (COPD).

This higher incidence could be due to similar inflammatory responses through the entire body’s immune system, or it could be connected to common factors in genetics or environment.

Gut bacteria and viruses

The bacteria present in the digestive system can also factor into the development of inflammatory bowel disease.

Lots of bacteria live in the gut. This is entirely normal. However, as diets and habits change, the ecology of bacteria in the gut (called the gut microbiome) can change, too. The gut microbiome can influence many aspects of health, from diabetes to liver disease to tumor risk. Scientists are working on identifying the healthy bacteria in the gut microbiome, as well as which bacteria are associated with the different types of inflammatory bowel disease.

Some of the bacteria in the gut microbiome may be inherited. Antibiotic medications could also impact it. One study has even found that it’s not necessarily the bacteria in the gut that lead to inflammatory bowel disease. Rather, it’s small particles called vesicles that are shed by the bacteria. These vesicles can penetrate the lining of the intestines and trigger an immune response.

Additionally, viruses have recently been identified as a possible influence in inflammatory bowel diseases. Viruses are present in the gut as well, forming the gut virome. A larger variety of viruses present in the gut virome has now been associated with inflammatory bowel disease.

Inflammatory bowel disease causes in children 

The number of children with inflammatory bowel disease seems to be on the rise. In 1991, the incidence of children with inflammatory bowel disease was 1.1 out of every 100,000 children. By 2002, that had risen to 2.4 out of every 100,000 children. Recently, some sources suggest that the incidence of inflammatory bowel disease may be as much as seven out of every 100,000 children.

In addition to the apparently rising incidence of inflammatory bowel disease among children, there may be an increased number of children with this disease being hospitalized. One study looked at hospitalization records of over 11 million patients, all of whom were age 20 or younger, and identified the patients who were discharged with a diagnosis of inflammatory bowel disease.

It was found that over the last decade, the number of discharged children with Crohn’s disease has increased 59%. The number of discharged children with ulcerative colitis has increased 71%. However, the study did not examine the children’s initial reason for hospitalization. The researchers did not differentiate between children who were admitted for reasons related to their inflammatory bowel disease and children who were admitted for unrelated medical issues; both groups are included in the statistics.

Diagnosing inflammatory bowel disease

The best way to keep individuals with inflammatory bowel disease healthy is to diagnose and treat symptoms as early as possible. One study found that the average time from initial symptoms to diagnosis is four to six months. Unfortunately, this means that the inflammation that characterizes this disease will likely have spread more.

The authors of this particular study suggest that more stringent diagnostic evaluation guidelines could help shorten the time to diagnosis.

Managing inflammatory bowel disease

By following their physicians’ orders, people with inflammatory bowel disease can manage their disease and continue to live life fully. Lifestyle management includes:

  • Taking all medications exactly as prescribed
  • Eating a healthy, physician-approved diet that avoids any triggering foods
  • Staying active as much as possible
  • Having an emergency kit on hand with clean clothes, wipes, etc.
  • Having a support system of friends, family, and medical professionals
  • Remembering that most people with inflammatory bowel disease are healthy more often than they are sick

You can find more help in our posts “What Are The Best Irritable Bowel Syndrome Treatment Options?” and “The IBS Diet Basics You Should Know.”

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