Nutritional Deficiencies in Crohn’s Disease & Colitis

By Andrea Bartels CNP NNCP RNT

Registered Nutritional Therapist

Iron deficiency

To diagnose Crohn’s, a variety of tests are usually required and include blood testing, medical imagery and a colonoscopy to confirm the presence of the disease. 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 percent of IBD patients typically have iron deficiency. (9) This is for two reasons. First, the substantial blood loss that occurs during flare- ups of ulceration leads to not only a loss of iron, but loss of red blood cells themselves. Oxygen-carrying hemoglobin becomes deficient, leading to the classic picture of iron-deficiency anemia, with fatigue, weakness, and pallor. But the second reason for iron deficiency in these patients has to do with absorptive capacity. Iron absorption becomes difficult as the small intestinal surface’s brush border of villi—used to transport nutrients from the digestive tract into the bloodstream—becomes compromised. This occurs from the damage that chronic inflammation causes, and by surgical removal of chronically ulcerated small intestine. Iron repletion is not a task easily accomplished through diet alone. The mineral is famously difficult to absorb, especially in its inorganic format. Supplementary iron has a reputation for having side effects like nausea and constipation, but this is most commonly experienced with iron sulfate and ferrous fumarate, which have poor absorbability. (4, 9) However, not all iron supplements produce these unpleasant side-effects. Compounding iron with amino acids, for example, can reduce the risk of side effects dramatically, simply because the iron is absorbed before it has any chance to cause discomfort. For an already sensitive digestive tract, it makes sense to recommend organic iron compounds that have greater absorbability.

Vitamin B-12

As with iron, deficiency of vitamin B12 is not usually about inadequate intake, but rather, blood loss and limited absorption by the Crohn’s patient. (1) Since vitamin B-12 is absorbed in the lowest portion (the ileum) of the small intestine, IBD patients who have had surgical removal of part of/all of their ileum would be at highest risk of deficiency. That’s why taking B-12 under the tongue (sublingually) is the sure-fire way to get it into the bloodstream. Methylcobalamin is the biologically active form of B-12 that, when used sublingually, is a more direct and efficient way (outside of injection) to ensure blood levels of B12 are there to support the nervous system and healthy hemoglobin synthesis in these patients.

Vitamin D

Being acutely ill with Crohn’s or colitis can mean little to no sun exposure, poor absorption, bowel resections, and inadequate dietary intake, so deficiencies in vitamin D are common. In fact, while Crohn’s is less common in children than in adults, in kids with inflammatory bowel disease vitamin D and iron are the two most prevalent nutritional deficiencies found. (3, 9) Vitamin D appears to influence the amount of inflammation generated by the immune system as it is an immune-modulator. Perhaps this is why researchers have found that high vitamin D levels appear to be a protective factor in Crohn’s disease, and potentially in colitis as well. In one study, vitamin D was demonstrated to be necessary for the regeneration of the epithelial cells within the small intestine of experimental mice, suggesting that further studies could identify if the same benefit could influence the condition of human IBD sufferers. (11). No matter what age, for individuals with excessive inflammation vitamin D supplementation presents an opportunity to promote normal functioning of the immune system.


Folate status is another nutrient that has a significant association with Crohn’s and colitis when compared to those without IBD (7). 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. (9,12) Since there are genetic variations in folate metabolism that could be at the foundation of IBD development, a biologically active form of folate– such as 5-methyltetrahydrofolate-may be indicated.

Vitamin K

In a Japanese study, deficiencies in vitamin K and vitamin D were very common among IBD patients, despite the fact that dietary consumption was higher in this group than Japanese guidelines for recommended daily intake. (5) Since vitamin K is manufactured by intestinal bacteria, and IBD flare ups are characterized by frequent stool evacuation, it stands to reason that flares leading to substantial loss of microbiota would impact vitamin K levels. In a study of children with Crohn’s and children with UC, 54 percent of those with CD and 43.7 percent of those with UC were deficient in vitamin K. (6) Not only is vitamin K required for healthy calcification of bones, but it also serves as a coagulant of the blood. Realizing that blood loss by IBD sufferers leads to the complication of anemia, supplementary vitamin K could be of benefit under medical supervision.

Nutritional Supplementation is Key

Currently, gastroenterologists prescribe a variety of anti-inflammatory drugs to manage the symptoms of Crohn’s in their patients. However many individuals find that pharmaceuticals alone are not effective in managing their symptoms. While there isn’t a specific dietary protocol recommended by gastroenterologists, patients are often advised to follow a low-residue diet. This is a diet low in fiber, to avoid further injury to the intestinal tract while it’s ulcerated. While it makes sense to minimize the intake of scratchy roughage fibres during active (bleeding) Crohn’s, using a low-fiber diet as long term management can limit a patient’s intake of essential nutrients found only in fruits and vegetables, such as folate, vitamin C and beta-carotene. Fruits and vegetables that are cooked and puréed, or juiced may be better tolerated. However, it can still be challenging to replenish depleted nutrient levels through diet alone due to the compromised absorption and blood loss experienced by Crohn’s patients. Therefore, appropriate dosing of specific nutritional supplementation could make a significant difference to nutritional status.


Certain circumstances once meant that Crohn’s flare-ups could be fatal due to the complications of excessive blood loss, blockages and multiple resection surgeries but today, prognosis is far better, with Crohn’s patients living higher quality lives, and living longer than ever before. Clearly, there are good reasons to employ supplementary nutrients in Crohn’s and colitis patients. 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 these patients stands a very good chance of improvement.


  1. Battat R., Kopylov U., Szilagyi A., Saxena A., Rosenblatt D.S., Warner M., Bessissow T., Seidman E., Bitton A. Vitamin B12 deficiency in inflammatory bowel disease: Prevalence, risk factors, evaluation, and management. Inflamm. Bowel Dis. 2014;20:1120-1128.
  2. Domislović V, Vranešić Bender D, Barišić A, Brinar M, Ljubas Kelečić D, Rotim C, Novosel M, Matašin M, Krznarić Ž. HIGH PREVALENCE OF UNTREATED AND UNDERTREATED VITAMIN D DEFICIENCY AND INSUFFICIENCY IN PATIENTS WITH INFLAMMATORY BOWEL DISEASE. Acta Clin Croat. 2020 Mar;59(1):109-118.
  3. Fritz J, Walia C, Elkadri A, Pipkorn R, Dunn RK, Sieracki R, Goday PS, Cabrera JM. A Systematic Review of Micronutrient Deficiencies in Pediatric Inflammatory Bowel Disease. Inflamm Bowel Dis. 2019 Feb 21;25(3):445-459.
  4. Kaitha S, Bashir M, Ali T. Iron deficiency anemia in inflammatory bowel disease. World J Gastrointest Pathophysiol. 2015;6(3):62-72.
  5. Kuwabara A, Tanaka K, Tsugawa N, Nakase H, Tsuji H, Shide K, Kamao M, Chiba T, Inagaki N, Okano T, Kido S. High prevalence of vitamin K and D deficiency and decreased BMD in inflammatory bowel disease. Osteoporos Int. 2009 Jun;20(6):935-42.
  6. Nowak JK, Grzybowska-Chlebowczyk U, Landowski P, et al. Prevalence and correlates of vitamin K deficiency in children with inflammatory bowel disease. Sci Rep. 2014;4:4768.
  7. Pan Y, Liu Y, Guo H, et al. Associations between Folate and Vitamin B12 Levels and Inflammatory Bowel Disease: A Meta-Analysis. Nutrients. 2017;9(4):382.
  8. Schäffler H, Schmidt M, Huth A, Reiner J, Glass ä, Lamprecht G. Clinical factors are associated with vitamin D levels in IBD patients: A retrospective analysis. J Dig Dis. 2018 Jan;19(1):24-32.
  9. Stein J, Dignass AU. Management of iron deficiency anemia in inflammatory bowel disease – a practical approach. Ann Gastroenterol. 2013;26(2):104-113.
  10. Yakut M, Ustün Y, Kabacam G, Soykan I. Serum vitamin B12 and folate status in patients with inflammatory bowel diseases. Eur J Intern Med. 2010 Aug;21(4):320-3.
  11. Zhao H, Zhang H, Wu H, Li H, Liu L, Guo J, Li C, Shih DQ, Zhang X. 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 Gastroenterol. 2012 May 30; 12():57.
  12. Zezos P, Papaioannou G, Nikolaidis N, Vasiliadis T, Giouleme O, Evgenidis N. Hyperhomocysteinemia in ulcerative colitis is related to folate levels. World J Gastroenterol. 2005;11(38):6038-6042.

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