What Is Inflammatory Bowel Disease And What Causes It?

Man with hand over his stomach holds three rolls of toilet paper. A symptom of gastroenteritis and inflammatory bowel disease.
Photo by nebari, c/o 123-rf.com

Inflammatory bowel disease (IBD) is a highly serious complaint for sufferers. The disease encompasses both Crohn’s disease (CD) and ulcerative colitis (UC). These are chronic intestinal inflammatory disorders of largely unknown etiology (Xavier & Podolsky, 2007). One common feature is that the condition is the result of an uncontrolled immunological response. Both have common features whilst there important differences between them too.

People with IBD often suffer from periods of disease flare-up and then a remission period before the next episode. It is highly debilitating (Ordas et al., 2012).

Diet is known to play a large part in the development of the disease (Knight-Sepulveda et al., 2015).

Ulcerative Colitis (UC)

This inflammatory disease affects the colon primarily. It is characterised by periods of relapse and remission.


The disease is most common in populations of well-developed nations, in Northern hemisphere countries and those who live in urban and city environments. The disease is increasing in those populations such as India where dietary habits are altering by adopting more Western-style diets.

The incidence of the disease is that it affects between 8 and 15 people in every 100,000. The prevalence is somewhere between 170 and 230 people who may experience some symptoms in every 100,000.

Caucasians and Jewish are most prone to the condition but this may simply be due to the level of reporting in those populations. Young adults are especially prone. Both men and women are affected equally but it is more common in women although the reasons are not that clear.   

The Disease

UC involves inflammation of the mucosa and submucosa of the large or lower intestine. The most common are affected is from the rectum to the anus but also extends into the colon for an uncertain distance. 

The main symptoms are rectal bleeding, a frequent need to produce stools and mucous discharge from the rectum.

Other implications include nausea and weight loss, tenesmus, lower abdominal pain, severe dehydration and rectal discharge which is infected. Constipation is another symptom when the inflammation is only constrained by the rectum. Then it is known as proctitis. It can be confused with piles.

The symptoms can last for months.

Potential Causes


A few studies have found that sudden increases in sugar consumption especially through binging might increase the risk of inflammatory bowel disease. 

In 2019, a study in mice conducted by the University of Alberta in Canada suggested that sugar might be a culprit in report published in the journal Scientific Reports. In that study, the mice had an increased susceptibility to colitis when they were only two days into a high-sugar diet compared to those on a more balanced less sugar based diet. The susceptibility to colitis was increased in all cases by the use of chemicals to induce the effect. The symptoms of colitis though were more severe in those mice on the high-sugar diet. 

The study showed that the mice on a high-sugar diet suffered greater intestinal damage and their immune system was also more badly affected.

The issues were alleviated by feeding the mice short-chain fatty acids (SCFAs). These are compounds that are often produced by gut bacteria and those that form the basis of probiotic bacterial mixes.

The other issue raised by the change in the guts of the mice was their increased permeability. The implication was that there is a link between the way our gut bacteria operate and the generation of neurodegenerative diseases such as Alzheimer’s and Parkinson’s.

Those mice whose gut permeability increased very rapidly because of the high sugar diet were more prone to bacterial products moving freely from the gut to the rest of the body. 

Possible Routes To Ameliorating Inflammatory Bowel Disease

One of the ways that inflammatory bowel diseases could be treated or at least reduced in impact is through the judicious use of probiotics and diets rich in fibre. It is well known that a healthy gut relies on the presence of a healthy gut microbiome. In other words a gut which contains a healthy population of bacteria producing substances such as short-chain fatty acids.

Food is also a key component. Foods which support a healthy gut flora and fauna are always welcome. It seems that fibre, especially soluble fibre is an excellent fuel for supporting these bacteria and encouraging the production of SFCAs. These SCFAs are part of the mechanism which supports a healthy immune system.

It is thought that a high-sugar diet coupled with a reduction in dietary fibre increase the proportion of unhealthy bacteria such as Escherichia coli. These are bacteria associated with inflammation and a poor or malfunctioning immune system in the gut.  


Knight-Sepulveda, K.; Kais, S.; Santaolalla, R.; Abreu, M.T. (2015) Diet and Inflammatory Bowel Disease. Gastroenterol. Hepatol. 11, pp. 511–520 (Article)

Ordas, I.; Eckmann, L.; Talamini, M.; Baumgart, D.C.; Sandborn, W.J. (2012) Ulcerative colitis. Lancet 380, pp. 1606–1619

Xavier, R.J.; Podolsky, D.K. (2007) Unravelling the pathogenesis of inflammatory bowel disease.  Nature 448, pp. 427–434 (Article)

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