Sugar and inflammatory bowel disease (IBD)

When you have inflammatory bowel disease (IBD) knowing what foods and drink affect your symptoms can be a bit of a minefield.

Some people with IBD have reported that sugar can cause a negative effect on their symptoms. Here we take a look at some of the reasons why that may be to help you make your own decision about whether it may be having an effect on your symptoms.

What is sugar?

Sugar is a natural ingredient found in many foods but also added to some foods during the manufacturing process.

There are different types of sugar:

  • Glucose - this is a simple sugar that naturally occurs in plants and fruits
  • Fructose - this is a simple sugar found naturally in fruits
  • Sucrose - this is a more complex sugar found in the sugar cane, roots of sugar beet and some fruits and plants
  • Lactose - found in milk and dairy

Sugar is a type of carbohydrate and when our body breaks it down it will either use it for energy, or if it already has enough for energy it will convert it to fat to store.


How sugar affects us

Sugar is hidden in many foods we eat today and our bodies are not designed to deal with large amounts of sugar - especially the highly processed ones which are common in our diets today.

Eating too much sugar has been linked with obesity and a number of health conditions - such as type 2 diabetes, heart disease and liver disease, as well as tooth decay.

Many of the sugars we eat are added sugars which have no nutritional value, unlike sugars which occur naturally in food such as fruit which provide other nutritional benefits.

Sugar and IBD

Some people with IBD avoid added sugars in their diet and find that it helps to control their symptoms. It is not known exactly why this may work for these people but some reasons include:

  • Sugar can change the balance of bacteria in the gut. There is currently a lot of research being done into the link between gut bacteria and IBD. Some people believe that having the wrong balance of gut bacteria can aggravate IBD symptoms
  • Eating processed sugar can cause an inflammatory response in the body. When sugars enter your body your blood sugar rises and in turn inflammatory messengers (known as cytokines) increase, causing inflammation in you body - not good news for people who already have elevated inflammation due to their IBD
  • Studies on animals have shown that sugar can suppress immune response1. If you have a condition, such as IBD, in which the immune system is already compromised, then suppressing the immune system further could have a negative impact on the body


  1. Nutter, R.L., Gridley, D.S., Kettering, J.D., et al., “Modification of a transplantable colon tumor and immune responses in mice fed different sources of protein, fat and carbohydrate." Cancer Letters, 18(1), 1983, pages 49-62


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