Inflammatory bowl diseaseIntroduction

There are two forms of inflammatory bowel disease (IBD):

  • Crohn's disease (CD)
  • Ulcerative colitis (UC)

They seem to have similar risk-modifying factors such as the high-animal product, high-sugar diet common in Western developed countries and low serum 25-hydroxyvitamin D [25(OH)D] levels.

Studies from Europe and France found higher rates of IBD at higher latitudes, while in the United States, it is most prevalent in in the northeast, where solar UVB doses are lowest in summer.

Mechanisms whereby vitamin D reduces risk of IBD include reducing inflammation by shifting cytokine production to less proinflammatory types and affecting expression of the NOD2 gene.

Those with IBD generally have impaired absorption of all nutrients including vitamin D, so would either have to take higher doses of vitamin D supplements or obtain vitamin D from UVB irradiance. However, if using thiopurine, there is an increased risk of nonmelanoma skin cancer.

Those with IBD should seek to achieve serum 25(OH)D levels of about 40 ng/mL, based on a randomized controlled trial of 1200 IU/day of vitamin D3 for those with CD, finding a 50% reduction in relapse rate. There is some risk of hypercalcemia at higher serum 25(OH)D levels. 

Crohn's disease

Crohn's disease is an inflammatory immune disease of the intestinal tract that causes thickening of the intestinal wall and inflammation of the intestinal lining (mucous membrane). Crohn's Disease can cause problems from the mouth to the anus. Symptoms include abdominal pain, diarrhea, fever, and weight loss.

CD usually affects the intestines, but may occur anywhere from the mouth to the end of the rectum. Symptoms depend on what part of the gastrointestinal tract is affected. Symptoms range from mild to severe, and can come and go with periods of flare-ups. The main symptoms of CD are: crampy abdominal (belly area) pain, fever, fatigue, loss of appetite, pain with passing stool (tenesmus), persistent, watery diarrhea, and unintentional weight loss.

CD has been described as an autoimmune disease, but a careful review of its pathology [Behr, 2010] indicates that it represents instead either an immune deficiency [Marks, 2006] or a secondary immune response to altered intestinal microbiota [Round, 2009].

Ulcerative colitis

UC is a chronic inflammation of the colon that produces ulcers in its lining. This condition is marked by abdominal pain, cramps, and loose discharges of pus, blood, and mucus from the bowel.

There appear to be about twice as many with UC than with CD based on a study in northern California with rates of 100.3 and 205.8/100,000, respectively1.

The Western diet seems to be an important risk factor for IBD:

We found several papers describing the positive association of animal meat and sweets and sugar with the occurrence of CD and UC. An analysis of Japanese epidemiological data suggested that the registered number of patients with CD or UC started to increase more than 20 years after an increased daily consumption of dietary animal meat and fats, and milk and dairy products, and after a decreased consumption of rice. Many studies implied a positive role of intestinal microbes in the occurrence of IBD. Intestinal environmental factors, such as Westernized food and intestinal microbes, seem to be involved in the increased occurrence of IBD2

There is a considerable amount of evidence that those with IBD have low serum 25-hydroxyvitamin D [25(OH)D] levels. This status often leads to low bone mass density since vitamin D helps with calcium absorption and metabolism.

Page last edited: 06 May 2011


  1. Herrinton, L. J. Liu, L. Lewis, J. D. Griffin, P. M. Allison, J. Incidence and prevalence of inflammatory bowel disease in a Northern California managed care organization, 1996-2002. Am J Gastroenterol. 2008 Aug; 103 (8): 1998-2006.
  2. Asakura, H. Suzuki, K. Kitahora, T. Morizane, T. Is there a link between food and intestinal microbes and the occurrence of Crohn's disease and ulcerative colitis?. J Gastroenterol Hepatol. 2008 Dec; 23 (12): 1794-801.