Ask the experts
Because ulcerative colitis (UC) and Crohn's disease affect the digestive tract many people believe that their diet has something to do with causing them. While the actual cause of these two diseases remains unknown, there has been some research that has shown an association between specific dietary habits and UC and Crohn's disease. These studies are done retrospectively (looking back) by examining the food records of people before being diagnosed with UC or Crohn's and comparing them with people who do not have either disease. The limitation to this is that there is a great deal of inaccuracy when people self-report their dietary intake, and when studies are done retrospectively, you can't say for sure that the specific food causes the disease. There could be factors outside of their diet that are the actual cause but were not part of the study. The only way to know for sure would be to perform studies where the only difference between the people with and without the disease is the specific food being studied.
Until more comprehensive research is done, it may be beneficial to know what the retrospective studies have shown:
Ulcerative colitis (UC):
- 145 people with UC & 305 controls found that people with UC consumed the most fast food (at least twice a week).
- 111 people with UC & 111 controls found that a higher consumption of sweets was positively associated with UC risk and a decreased risk of UC was found in those with a higher intake of vitamin C.
- 54 people with UC & 144 controls found an increased risk for UC with high sucrose (table sugar) consumption, a high fat intake (particularly animal fat), and increased dietary cholesterol consumption. A decreased risk was found in those with high intakes of fluids, magnesium, vitamin C and fruit.
Crohn's disease (CD):
- 152 people with CD & 305 controls found an increased risk for CD in people with high intakes of sucrose (55 g or more each day) and a decreased risk for people with a high fiber intake (15 g or more each day).
- 128 people with CD & 128 controls found that the consumption of sugar and sweeteners, sweets, and fat was positively associated with CD risk.
- 33 people with CD & 144 controls found a risk for those with a high sucrose consumption and a decreased risk for those with a high fructose (fruit sugar) intake and a high intake of vegetables.
The consistent trend throughout each of the studies follows the advice found in the dietary guidelines for all healthy Americans. The best diet to follow is one that is balanced with foods from each of the food groups and limited in sugar and fat.
Quick GuideDigestive Disorders: Common Misconceptions
Medically reviewed by John A. Daller, MD; American Board of Surgery with subspecialty certification in surgical critical care
"Clinical manifestations, diagnosis and prognosis of Crohn disease in adults"
"Clinical manifestations, diagnosis, and prognosis of ulcerative colitis in adults"
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Last Editorial Review: 8/4/2017