Malabsorption, Celiac Disease, IBD and Vitamin Deficiency
How malabsorption in celiac disease, Crohn's disease, ulcerative colitis and pancreatic problems can lead to vitamin deficiency, which vitamins are involved, and why medical care comes first.
Content last updated . This page has not been medically reviewed.
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If you have ongoing diarrhea, unplanned weight loss or other bowel symptoms, see a clinician. MedlinePlus lists chronic diarrhea, abnormal stools, weight loss and gas among the usual signs of malabsorption, and says treatment depends on the cause. [1] Vitamin pills do not fix the underlying cause, and the cause needs to be found. This page is information only. It does not tell anyone to start, stop or change a medicine, a diet or a supplement.What malabsorption means
MedlinePlus explains that in a malabsorption syndrome the small intestine cannot absorb nutrients from foods. [1] Causes it lists include celiac disease, short bowel syndrome (which happens after surgery that removes half or more of the small intestine) and some medicines. [1] The NHS describes the same idea for coeliac disease: malabsorption can lead to a deficiency of vitamins and minerals. [2]Fat-soluble vitamins (A, D, E and K) depend on fat digestion. A 2024 review says fat malabsorption can show up as steatorrhea (fatty stools), malnutrition and deficiencies of fat-soluble vitamins. [3] MedlinePlus makes the same point for vitamin E: the body needs fat to absorb it. [4] See fat-soluble vs water-soluble vitamins.
Conditions and the vitamins reported
| Condition | What sources report | Strength of evidence |
|---|---|---|
| Celiac disease | NHS: malabsorption can lead to vitamin and mineral deficiency. [2] MedlinePlus lists celiac disease among causes of low vitamin A. [5] | Established nutritional role |
| Gluten-free diet in celiac disease | A 2016 review of the diet found micronutrients, in particular vitamin D, B12 and folate, to be poor. [6] A 2025 review in children says nutritional adequacy of the gluten-free diet cannot be assumed. [7] | Mixed (reviews, not a single trial) |
| Crohn's disease | NHS: it can make it harder to absorb nutrients and can cause vitamin deficiencies. [8] | Established nutritional role |
| Ulcerative colitis | NHS: it can stop you getting enough vitamins and minerals from food. [9] | Established nutritional role |
| Inflammatory bowel disease overall | A 2015 review reports micronutrient deficiencies in more than half of patients; the most common include iron, B12, vitamin D, vitamin K, folic acid and others. It adds that they are more common in Crohn's disease than ulcerative colitis, and in active disease. [10] | Mixed (review; figures vary by study) |
| IBD, hospitalized adults | A 2024 chart review concluded that copper and vitamin A, E and K deficiencies are particularly underrecognized. [11] | Insufficient evidence (retrospective, one center) |
| Pancreatic enzyme problems (exocrine pancreatic insufficiency) | The American Gastroenterological Association advises suspecting it in chronic pancreatitis and considering it in celiac and Crohn's disease. [12] Fat malabsorption can lead to fat-soluble vitamin deficiency. [3] | Established nutritional role |
| After stomach or bowel surgery | NHS: part-stomach removal raises B12 deficiency risk. [13] See vitamins after bariatric surgery. | Established nutritional role |
Why testing is harder in bowel disease
Blood levels of several vitamins fall when inflammation is active, so a low result may partly reflect inflammation. A 2023 review says this is why a marker of inflammation, C-reactive protein, must always be measured alongside. [14] For B12, the same IBD review says a definite diagnosis cannot be made from serum levels alone. [10] Details are in vitamin B12 tests and other vitamin tests.Treatment is clinician-led
When absorption is the problem, the amount and route a clinician chooses can differ from what suits a person with a low-intake diet. Sources do not fully agree on B12. A 2024 narrative review says that in B12 malabsorption oral supplements are likely insufficient and injections are preferred. [15] A 2025 family-physician review says oral B12 can be used in most patients and is noninferior to intramuscular. [16] The same review says intramuscular treatment should be considered in severe deficiency or when there are neurologic signs. [16] Which route suits a person is a clinician's decision. See vitamin B12 injections.Frequently asked questions
Can celiac disease cause vitamin deficiency?
Yes. NHS says the malabsorption that can occur in coeliac disease can lead to a deficiency of vitamins and minerals. [2]
Does a gluten-free diet fix vitamin levels?
Not always. A 2016 review found micronutrients, in particular vitamin D, B12 and folate, to be poor in gluten-free diets, and a 2025 review says adequacy cannot be assumed in children. [6] [7]
Which vitamins are most often low in Crohn's disease?
A 2015 review lists iron, B12, vitamin D, vitamin K, folic acid, selenium, zinc, vitamin B6 and vitamin B1 as the most common deficiencies in IBD. [10]
Why are fat-soluble vitamins affected by fat malabsorption?
They need fat digestion to be absorbed. A 2024 review lists deficiencies of fat-soluble vitamins among the effects of fat malabsorption. [3]
Is a single blood test enough to diagnose a deficiency in IBD?
No for B12. A 2015 review says a definite diagnosis cannot be established by serum levels alone. [10]
More details: evidence, limits and cautions
The details behind this page: cautions, limits of the evidence and where sources disagree. Open any note to read it.
How to read the evidence labels
Labels used on this page: established nutritional role / deficiency treatment, mixed, insufficient evidence and Proper evidence not found.
Safety
- Medicines: several medicines used in bowel disease can affect vitamin status or cause anemia, including methotrexate and sulfasalazine. [17] NHS names the same two among medicines that reduce folate. [13] Do not stop a prescribed medicine. Ask the prescriber or pharmacist, and see medication interactions.
- Children: a 2025 review says nutritional adequacy of the gluten-free diet cannot be assumed in children with celiac disease, so ask the child's care team about monitoring. [7]
- Fat-soluble vitamins in excess: more is not safer. Vitamin A in particular has pregnancy cautions; see vitamin A excess and pregnancy.
- Surgery, kidney and liver disease: tell the surgeon and care team about every supplement; see vitamins before surgery.
- Product quality: see quality testing and certifications.
References
- MedlinePlus Health Topics (US National Library of Medicine). Malabsorption Syndromes. Read 2026-10-23.
- NHS (UK). Coeliac disease: Complications. Page last reviewed 31 March 2023. Read 2026-10-23.
- Fat digestion and absorption: Normal physiology and pathophysiology of malabsorption, including diagnostic testing. PubMed record. Nutr Clin Pract. 2024 (abstract read). Read 2026-10-23.
- MedlinePlus Medical Tests (US National Library of Medicine). Vitamin E (Tocopherol) Test. Read 2026-10-23.
- MedlinePlus Medical Encyclopedia (US National Library of Medicine). Vitamin A blood test. Review date 10/1/2025. Read 2026-10-23.
- Gluten free diet and nutrient deficiencies: A review. PubMed record. Clin Nutr. 2016 (abstract read). Read 2026-10-23.
- Celiac Disease as a Model of Intestinal Malnutrition: Mechanisms and Nutritional Management. PubMed record. Nutrients. 2025 (abstract read; narrative review in children). Read 2026-10-23.
- NHS (UK). Crohn's disease. Page last reviewed 14 April 2025. Read 2026-10-23.
- NHS (UK). Ulcerative colitis. Page last reviewed 20 August 2026. Read 2026-10-23.
- Micronutrient deficiencies in inflammatory bowel disease. PubMed record. Curr Opin Clin Nutr Metab Care. 2015 (abstract read). Read 2026-10-23.
- Micronutrient deficiencies in inflammatory bowel disease: an incidence analysis. PubMed record. Eur J Gastroenterol Hepatol. 2024 (abstract read; retrospective chart review of hospitalized adults). Read 2026-10-23.
- AGA Clinical Practice Update on the Epidemiology, Evaluation, and Management of Exocrine Pancreatic Insufficiency: Expert Review. PubMed record. Gastroenterology. 2023 (abstract read). Read 2026-10-23.
- NHS (UK). Vitamin B12 or folate deficiency anaemia: Causes. Page last reviewed 20 February 2023. Read 2026-10-23.
- Pitfalls in the interpretation of blood tests used to assess and monitor micronutrient nutrition status. PubMed record. Nutr Clin Pract. 2023 (abstract read). Read 2026-10-23.
- A Brief Overview of the Diagnosis and Treatment of Cobalamin (B12) Deficiency. PubMed record. Food Nutr Bull. 2024 (abstract read). Read 2026-10-23.
- Vitamin B12 Deficiency: Common Questions and Answers. PubMed record. Am Fam Physician. 2025 (abstract read). Read 2026-10-23.
- Approach to anaemia in gastrointestinal disease: A position paper by the ESPGHAN Gastroenterology Committee. PubMed record. J Pediatr Gastroenterol Nutr. 2025 (abstract read). Read 2026-10-23.
Education, not medical advice. This page is for general information. It does not diagnose or treat any condition and is not a substitute for care from a qualified health professional. Natural does not automatically mean safe. Ask a clinician or pharmacist before changing your care, especially if you take medication, are pregnant or breastfeeding, or have a health condition.