Crohn’s disease is a type of inflammatory bowel disease (IBD) in which parts of the digestive tract become inflamed. While the exact cause of Crohn’s disease is unknown, genetic and immune system factors are believed to play a role in its development. Now, new research has revealed that there could be a direct link between adipose tissue (fatty tissue) in the gut and Crohn’s disease. Please continue reading to find out more. 

What is inflammatory bowel disease?

Inflammatory bowel disease (IBD) is a condition in which there is chronic inflammation of the digestive tract. The two main types of IBD are:

Ulcerative colitis

This is a condition in which there is inflammation and ulceration in the superficial inner lining of the colon (large intestine) and rectum.

Crohn's disease

In this condition, there is intestinal inflammation in the last part of the small intestine and the large intestine. The inflammation often spreads to the deeper layers. 

Some 3 million patients suffer from inflammatory bowel diseases (either Crohn’s disease or ulcerative colitis) in the United States. Untreated IBD can lead to debilitating and potentially life-threatening complications.

What tissues are affected by Crohn's disease?

The inflammation caused by Crohn's disease can involve different parts of the digestive tract in different patients. Crohn's disease is essentially an intestinal disease. It commonly affects the last part of the ileum (small intestine) and the colon (large intestine). The inflammatory alterations in intestinal anatomy in Crohn’s disease patients frequently spread to the deeper layers of the bowel.

Is steatorrhea common in Crohn's?

Steatorrhea is the presence of abnormally large quantities of fat in the feces due to reduced absorption of fats in the intestines. In patients with Crohn’s disease, the absorption of different substances, including fats, is altered. This can lead to steatorrhea (fats in the stool).

Both Crohn’s and ulcerative colitis can cause diarrhea, abdominal pain, rectal bleeding, weight loss, and fatigue. In addition, steatorrhea can occur in IBD, especially if it involves large portions of the intestines. 

Why is there fat wrapping in Crohn's disease?

Several changes occur in the serosal connective tissue in Crohn’s disease patients. One of the phenomena that has been recognized is fat wrapping around the intestines (fatty tissue surrounding the areas of inflammation). 

Also known as creeping fat, this is an extraintestinal manifestation of Crohn’s disease (it occurs outside the intestines). Fat creeping involves the migration of mesenteric adipose tissue (MAT) or visceral fat tissue to the sites of inflammation. In other words, the mesenteric fat naturally present in the abdominal area wraps itself around the bowel wall, causing it to thicken. In patients with advanced Crohn’s disease, the creeping fat can cover up to half of the intestines.

Can you be fat and have Crohn's disease?

The prevalence of IBD has been increasing in recent decades, especially in developed nations like the United States. Experts believe that part of the reason is a change in diet and lifestyle. The rise in IBD has paralleled the increasing prevalence of obesity, suggesting a possible causative link between the two conditions.

How do people with Crohn's disease incorporate fat into their bodies?

New research has revealed that there is a direct link between fatty tissue and Crohn's disease. The 2021 study done at the University of Limerick in Ireland suggests that Crohn's disease, traditionally labeled as an inflammatory bowel condition, may indeed be a fatty intestine condition.

A team of gastroenterology and surgical specialists with diverse expertise conducted the research at the University of Limerick. The research was done at University Hospital Limerick and involved subjecting patients with Crohn's to body composition analysis. The researchers found that people who have Crohn's appear to preferentially accumulate fat in the lower parts of the gut rather than the abdomen. The study showed that the areas that contain the intestines and where Crohn’s-related ulcers and inflammatory lesions occur have higher fat depositions. These are areas that typically have relatively less overall fat compared to the abdomen. Therefore, it appears that Crohn’s patients appear to preferentially lay down fat in locations in the intestine where inflammation is present, suggesting a direct link between Crohn’s disease and fatty tissue.

The University of Limerick researchers also found that patients with Crohn's disease incorporate fat into their bodies in a way that is different from healthy people without this disorder. 

The emerging new knowledge and novel approaches such as those used in the UL School of Medicine research benefit IBD patients significantly. An example is the creation of a new diagnostic test that differentiates Crohn's disease and ulcerative colitis using blood tests (blood-borne biomarkers). This has practical applications in real-world clinical care because it allows doctors to monitor response to treatment without the need for invasive procedures like endoscopy in people with Crohn’s disease.

References

1. https://www.cdc.gov/ibd/data-statistics.htm
2. https://www.mayoclinic.org/diseases-conditions/inflammatory-bowel-disease/symptoms-causes/syc-20353315
3. https://www.mayoclinic.org/diseases-conditions/crohns-disease/symptoms-causes/syc-20353304
4. https://www.calprotectina.com/en/crohns-disease/
5. https://pubmed.ncbi.nlm.nih.gov/1422768/
6. https://www.sciencedaily.com/releases/2021/10/211004104215.htm
7. https://www.nature.com/articles/s41575-020-00379-0
8. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5028803/