Crohn’s disease and ulcerative colitis are inflammatory bowel diseases (IBD) characterized by recurring symptoms that include intestinal inflammation, bleeding, bloating, and pain, as well as frequent evacuation of loose, bloody stool. Ulcerative colitis is confined to the mucosal layer of the colon, while the ulceration of Crohn’s colitis can occur anywhere in the digestive tract and penetrate beyond the mucosal layer of the bowel into the muscular layer beneath. (19) Individuals with either inflammatory condition have an elevated risk of nutritional deficiencies. (3)(7)
Nutritional deficiencies in Crohn’s disease
In cases of Crohn’s disease, chronic inflammation leads to structural changes in the small intestine and the absorptive surface becomes compromised, quickly leading to nutritional deficiencies. Additionally, the surgical removal of portions of the diseased intestine can leave the patient with diminished absorption of nutrients, giving rise to potential long-term health problems that extend beyond the digestive tract. (3)(5) That’s why it’s important to understand the nutritional deficiencies Crohn’s disease patients are most vulnerable to developing.
1. Iron
To diagnose Crohn’s disease, a variety of tests are usually required, including blood tests, medical imagery, and a colonoscopy to confirm the presence of the condition. Checking blood levels of ferritin and hemoglobin will usually identify the most common nutrient deficiency in Crohn’s and colitis patients: iron-deficiency anemia. In fact, 60 to 80% of IBD patients typically have an iron deficiency. (17)
In individuals with Crohn’s disease, factors that contribute to anemia include iron malabsorption, blood loss, and anemia of inflammation, a condition in which inflammatory proteins interfere with iron transport in specific white blood cells and cells lining the intestines. (16)

2. Vitamin B12
As with iron, deficiency of vitamin B12 commonly occurs as a result of blood loss and limited absorption. Since vitamin B12 is absorbed in the lowest portion of the small intestine (the ileum), IBD patients who have had full or partial surgical removal of their ileum are at the highest risk of deficiency. (1) Taking B12 sublingually (under the tongue) is an effective way to get it into the bloodstream. Methylcobalamin is the biologically active form of B12 that, when used sublingually, is a more direct and efficient way (other than injection) to ensure adequate blood levels of B12 are present to support the nervous system and healthy hemoglobin synthesis in these patients. (2)
3. Vitamin D
While Crohn’s disease is less common in children than in adults, vitamin D and iron are the two most prevalent nutritional deficiencies found in kids with inflammatory bowel disease. (7)(17) Researchers have found that high vitamin D levels appear to be a protective factor in Crohn’s disease and potentially in colitis. This protective effect may be attributed to vitamin D’s ability to modulate immune function and inflammation. In one experimental study, vitamin D was demonstrated to be necessary for the regeneration of the epithelial cells within the small intestine of mice, suggesting that further studies could identify if the same benefit could influence the condition of human IBD sufferers. (20)
4. Folate
Scientific literature states that the relationship between folate and IBD may be bidirectional—IBD can result in impaired folate absorption, and folate deficiency may be associated with the development of IBD. Specifically, folate levels may affect the interactions between the gut microbiota (microbes) and immune responses involved in the disease process. Not only that, but the implications of low folate status include high blood levels of homocysteine, which is a risk factor for cardiovascular events such as thrombosis (blood clot formation). (17)(21) Folate supplementation can be used to improve nutrient levels and help prevent other conditions in individuals with IBD. (14)
5. Vitamin K
Vitamin K is required for healthy bone calcification (the deposit of calcium in bones) and blood clotting. (12)(13) As vitamin K is manufactured by intestinal bacteria and IBD flare-ups are characterized by frequent stool evacuation, it stands to reason that flare-ups leading to substantial loss of microbiota would impact vitamin K levels. In a study of children with IBD, 54% of those with Crohn’s disease and 43.7% of those with ulcerative colitis were deficient in vitamin K. (12) Overall, a meta-analysis examining vitamin deficiencies in IBD found that fat-soluble vitamins, including vitamin K, are generally lower in IBD patients, and concluded that supplementation may be needed. (6)
Diet and supplementation for Crohn’s disease
The Western diet (high in protein and fat and low in produce) has been suggested as a contributing factor to the increasing incidence of IBD. There is scientific evidence that diet may in fact influence the risk of IBD and intestinal inflammation. Individuals with IBD commonly seek dietary advice to help manage their condition; however, no specific IBD diet currently exists. (10)

In addition, individuals with IBD who become malnourished may require oral supplements, enteral nutrition (tube feeding), or, in the case of certain advanced complications, parenteral nutrition (intravenous nutrient administration). (5)
The bottom line
Over the last 25 years, the quality of life and life expectancy of individuals with IBD has significantly increased. (11) In addition to appropriate treatment, dietary supplements, including iron, vitamin B12, vitamin D, folate, and vitamin K may be beneficial for addressing nutrient deficiencies that commonly occur in IBD. (6)(8)(14)(17) With careful attention to nutritional status, stress management, and regular monitoring by health care practitioners who are well-versed in the challenges of Crohn’s and colitis, the well-being of anyone afflicted with this condition stands a very good chance of improvement.
- Battat, R., Kopylov, U., Szilagyi, A., Saxena, A., Rosenblatt, D. S., Warner, M., … & Bitton, A. (2014). Vitamin B12 deficiency in inflammatory bowel disease: Prevalence, risk factors, evaluation, and management. Inflammatory Bowel Diseases, 20, 1120–1128.
- Bensky, M. J., Ayalon-Dangur, I., Ayalon-Dangur, R., Naamany, E., Gafter-Gvili, A., Koren, G., & Shiber, S. (2019). Comparison of sublingual vs. intramuscular administration of vitamin B12 for the treatment of patients with vitamin B12 deficiency. Drug Delivery and Translational Research, 9(3), 625–630.
- Crohn’s and Colitis Canada. (n.d.). Malnutrition and dehydration. Crohn’s and Colitis Canada. Retrieved from https://crohnsandcolitis.ca/Test/About-Crohn-s-Colitis/IBD-Journey/Diet-and-Nutrition-in-IBD/Malnutrition-and-Dehydration
- Domislović, V., Vranešić Bender, D., Barišić, A., Brinar, M., Ljubas Kelečić, D., Rotim, C., … & Krznarić, Ž. (2020). High prevalence of untreated and undertreated vitamin D deficiency and insufficiency in patients with inflammatory bowel disease. Acta Clinica Croatica, 59(1), 109-118.
- Donnellan, C. F., Yann, L. H., & Lal, S. (2013). Nutritional management of Crohn’s disease. Therapeutic Advances in Gastroenterology, 6(3), 231-242.
- Fabisiak, N., Fabisiak, A., Watala, C., & Fichna, J. (2017). Fat-soluble vitamin deficiencies and inflammatory bowel disease: Systematic review and meta-analysis. Journal of Clinical Gastroenterology, 51(10), 878–889.
- Fritz, J., Walia, C., Elkadri, A., Pipkorn, R., Dunn, R. K., Sieracki, R., … & Cabrera, J. M. (2019). A systematic review of micronutrient deficiencies in pediatric inflammatory bowel disease. Inflammatory Bowel Diseases, 25(3), 445-459.
- Gargallo-Puyuelo, C. J., Alfambra, E., García-Erce, J. A., & Gomollon, F. (2018). Iron treatment may be difficult in inflammatory diseases: Inflammatory bowel disease as a paradigm. Nutrients, 10(12), 1959.
- Kaitha, S., Bashir, M., & Ali, T. (2015). Iron deficiency anemia in inflammatory bowel disease. World Journal of Gastrointestinal Pathophysiology, 6(3), 62-72.
- Knight-Sepulveda, K., Kais, S., Santaolalla, R., & Abreu, M. T. (2015). Diet and inflammatory bowel disease. Gastroenterology & Hepatology, 11(8), 511–520.
- Kuenzig, M. E., Manuel, D. G., Donelle, J., & Benchimol, E. I. (2020). Life expectancy and health-adjusted life expectancy in people with inflammatory bowel disease. Canadian Medical Association Journal, 192(45), E1394–E1402.
- Nowak, J. K., Grzybowska-Chlebowczyk, U., Landowski, P., Szaflarska-Poplawska, A., Klincewicz, B., Adamczak, D., … & Walkowiak, J. (2014). Prevalence and correlates of vitamin K deficiency in children with inflammatory bowel disease. Scientific Reports, 4, 4768.
- Office of Dietary Supplements. (2020, June 3). Vitamin K. Retrieved from https://ods.od.nih.gov/factsheets/VitaminK-HealthProfessional/
- Pan, Y., Liu, Y., Guo, H., Jabir, M. S., Liu, X., Cui, W., & Li, D. (2017). Associations between folate and vitamin B12 levels and inflammatory bowel disease: A meta-analysis. Nutrients, 9(4), 382.
- Schäffler, H., Schmidt, M., Huth, A., Reiner, J., Glass, Ä., & Lamprecht, G. (2018). Clinical factors are associated with vitamin D levels in IBD patients: A retrospective analysis. Journal of Digestive Diseases, 19(1), 24–32.
- Semrin, G., Fishman, D. S., Bousvaros, A., Zholudev, A., Saunders, A. C., Correia, C. E., … & Weinstein, D. A. (2006). Impaired intestinal iron absorption in Crohn’s disease correlates with disease activity and markers of inflammation. Inflammatory Bowel Diseases, 12(12), 1101–1106.
- Stein, J., & Dignass, A. U. (2013). Management of iron deficiency anemia in inflammatory bowel disease – a practical approach. Annals of Gastroenterology, 26(2), 104–113.
- Yakut, M., Ustün, Y., Kabaçam, G., & Soykan, I. (2010). Serum vitamin B12 and folate status in patients with inflammatory bowel diseases. European Journal of Internal Medicine, 21(4), 320–323.
- Waugh, N., Cummins, E., Royle, P., Kandala, N. B., Shyangdan, D., Arasaradnam, R., Clar, C., & Johnston, R. (2013). Faecal calprotectin testing for differentiating amongst inflammatory and non-inflammatory bowel diseases: Systematic review and economic evaluation. Health Technology Assessment, 17(55), xv–211.
- Zhao, H., Zhang, H., Wu, H., Li, H., Liu, L., Guo, J., … & Zhang, X. (2012). Protective role of 1,25(OH)2 vitamin D3 in the mucosal injury and epithelial barrier disruption in DSS-induced acute colitis in mice. BMC Gastroenterology, 12, 57.
- Zezos, P., Papaioannou, G., Nikolaidis, N., Vasiliadis, T., Giouleme, O., & Evgenidis, N. (2005). Hyperhomocysteinemia in ulcerative colitis is related to folate levels. World Journal of Gastroenterology, 11(38), 6038-6042.