How Diet Impacts IBD

Does diet cause Crohn’s disease or ulcerative colitis?

The exact cause of IBD is not fully understood, though research suggests it is the result of an abnormal immune response triggered by a combination of factors, including a person’s genetic makeup and likely various environmental exposures over a lifetime. However, exactly what “exposures” may contribute to the development of IBD is still being researched. There are many environmental risk factors that have been explored, including smoking, infections, antibiotic or other medication use, hygiene, pollution, climate, and diet.


While diet may play some role in determining a person’s risk for developing IBD, diet alone does not cause IBD. For instance, there is some research to suggest that people whose diets contain higher amounts of fruits, vegetables, and fiber may have a lower risk of developing IBD, whereas those who have a higher intake of saturated fat, red meat or animal fats, and processed foods may have an increased risk of developing IBD.1,2 Many people may worry that they could have done something differently to avoid developing IBD, but, remember, diet likely represents only a small piece of the puzzle.


Can foods cause inflammation?

An IBD flare (active disease) occurs when symptoms develop as the result of active inflammation in the bowel. However, there are times when someone with ulcerative colitis or Crohn’s disease may have an increase in their symptoms (diarrhea, bloating, cramping) without necessarily having inflammation, and this can be related to a variety of issues that include individual food sensitivities, irritable bowel syndrome, infections, etc.


While researchers are working to understand more about how various foods, such as those that are ultra-processed (potato chips, sodas, candy) or have added sugars, emulsifiers, and other additives, may contribute to the underlying inflammation in IBD, there is currently no direct evidence to suggest that specific foods cause inflammation in IBD. However, there are certain foods that may lead to unpleasant symptoms even if they are not causing inflammation. Paying attention to your diet may help you reduce symptoms.


Does my diet increase the risk of getting colorectal cancer?

IBD patients may be at higher risk for developing colon polyps and cancer. Those who are at higher risk include patients with long-standing disease (more than 8–10 years) with inflammation involving more than a third of their colon or long-standing uncontrolled inflammation of the colon, patients with coexisting primary sclerosing cholangitis (PSC), and certainly those with a family history of colorectal cancer. There are some studies that have linked diets high in red meat (beef, pork, lamb), processed meats (lunch meats, hotdogs, bacon), or processed foods to an increased risk of colon cancer,3 though the actual impact these have on cancer risk is not known, particularly in the IBD population.


Given many of these foods are also hypothesized to play a role in increasing the risk of IBD, and that heavily processed foods offer little nutritional value, it may be beneficial to reduce their intake for various reasons. If you are interested in modifying your diet for this or other purposes, it is best to have a discussion with your doctor or a registered dietitian.


Learn more about colorectal cancer here.


  1. Ananthakrishnan AN, Khalili H, Konijeti GG, et al. A prospective study of long-term intake of dietary fiber and risk of Crohn’s disease and ulcerative colitis. Gastroenterology. 2013;145(5):970-7.
  2. Lee D, Aldenberg L, Compher C, et al. Diet in the pathogenesis and treatment of inflammatory bowel diseases. Gastroenterology. 2013;148(6):1087-106.
  3. Farvid MS, Sidahmed E, Spence ND, Mante Angua K, Rosner BA, Barnett JB. Consumption of red meat and processed meat and cancer incidence: A systematic review and meta-analysis of prospective studies. Eur J Epidemiol. 2021;36(9):937-951. doi:10.1007/s10654-021-00741-9.