Vitamin D and inflammatory bowel diseases

Table 1 Key findings

Ref.	Study design	Population/sample size	VD assessment	IBD type	Association between VD and IBD
Sharifi et al[8], 2020	Randomized, double-blinded, placebo-controlled trial	90 patients with UC	Serum 25(OH)D levels	UC	VD supplementation decreases the CD40 L gene expression in patients with mild-to-moderate UC
Schardey et al[9], 2019	Prospective cohort study	200 outpatients with IBD	Serum 25(OH)D levels	UC, CD	The incubation VD resulted in remarkably reduced populations of pro-inflammatory CD4+ and CD8+ T cells
Ananthakrishnan et al[25], 2012	Prospective cohort study	122 CD women	Serum 25(OH)D levels	CD	Higher levels of VD reduce the risk of incident CD in women
Sadeghian et al[29], 2016	Meta-analysis	63 studies	Serum 25(OH)D levels	CD	Patients with CD had lower VD levels compared with their healthy counterparts. There was an inverse correlation between VD levels and severity of CD
Topalova-Dimitrova et al[39], 2023	Cross-sectional study	92 patients with IBD, 14 health controls	Serum 25(OH)D levels	UC, CD	Reverse correlation between VD and inflammatory markers
Andres et al[30], 2024	Retrospective cohort study	204 patients with IBD	Serum 25(OH)D levels	UC, CD	In younger patients, VD was associated with adverse clinical outcomes, but the same trend was not seen in older patients
Yang et al[33], 2024	Prospective observational study	106 patients with IBD	Serum 25(OH)D levels	UC, CD	Female sex and early age at diagnosis were identified as statistically significant risk factors for VD deficiency
Domislović et al[34], 2020	Cross-sectional study	185 patients with IBD	Serum 25(OH)D levels, VD supplement	UC, CD	VD deficiency common in IBD patients but the proportion of untreated and undertreated patients is also considerably high
Gubatan et al[35], 2019	Systematic review and meta-analysis	27 studies, 8316 patients with IBD	Serum 25(OH)D levels	UC, CD	Low VD levels are associated with increased odds of disease activity, mucosal inflammation, low quality of life, and future clinical relapse
Yeaman et al[36], 2023	Retrospective observational study	325 patients with IBD	Serum 25(OH)D levels	UC, CD	VD level is negatively correlated with FCP and may be considered an adjunct biomarker at this stage
Koureta et al[37], 2025	Cross-sectional observational study	325 patients with IBD	Serum 25(OH)D levels	UC, CD	In CD, higher CRP and stool calprotectin are usually detected in patients with low than normal VD levels, rendering VD a possible activity marker, something that cannot be supported for patients with UC.
Song et al[38], 2024	Retrospective, cross-sectional observational study	1989 patients with IBD	Serum 25(OH)D levels	UC, CD	There was a negative association between CRP levels and VD in hospitalized patients with IBD
Blanck and Aberra[40], 2013	Cross-sectional study	34 patients with UC	Serum 25(OH)D levels	UC	VD deficiency is common among patients with active UC, particularly those requiring corticosteroids
Guzman-Prado et al[41], 2020	Systematic review and meta-analysis	12 randomized controlled trials and 4 observational studies	VD supplement	UC, CD	VD supplementation is effective at correcting VD levels and is associated with improvement in clinical and biochemical disease activity scores
Sharifi et al[42], 2016	Clinical controlled trial	90 patients with UC	VD supplement	UC	CRP and erythrocyte sedimentation rate were lower at 3 months after the administration of VD in patients with UC and VD deficiency
Alrefai et al[43], 2017	Retrospective cohort study	201 patients with CD	Serum 25(OH)D levels	CD	VD concentrations showed a significant inverse association with both high-sensitivity-CRP level and disease activity levels
Ham et al[44], 2021	Retrospective cohort study	711 patients with CD, 764 patients with UC	Serum 25(OH)D levels	UC, CD	Higher CD activity index, partial Mayo scores, and CRP levels were linked with decreased levels of VD. Severe VD deficiency seems to correlate to the disease extent in UC
Meckel et al[45], 2016	Prospective cohort study	230 patients with UC	Serum 25(OH)D levels	UC	In patients with UC, VD concentration is inversely correlated with mucosal inflammation and disease activity
Ananthakrishnan et al[46], 2013	Retrospective cohort study	3217 patients with IBD	Serum 25(OH)D levels	UC, CD	Low VD is associated with increased risk of surgery and hospitalization in both CD and UC, and normalization of VD status is associated with a reduction in the risk of CD-related surgery
Venkata et al[47], 2017	Retrospective cohort study	196 patients with CD	Serum 25(OH)D levels	CD	Normal or adequate VD stores may be protective in the clinical course of CD
Dan et al[48], 2024	Longitudinal cohort study	5474 patients with IBD	Serum 25(OH)D levels	UC, CD	Increased VD levels are independently associated with reduced bowel resection risk in IBD. This association was significant in UC but may not be stable in CD
Hlavaty et al[50], 2014	Retrospective cohort study	220 patients with IBD	Serum 25(OH)D levels	UC, CD	VD low levels were correlated with poorer quality of life
Ulitsky et al[51], 2011	Retrospective cohort study	504 patients with IBD	Serum 25(OH)D levels	UC, CD	VD deficiency is associated with lower quality of life in CD, but not UC
Torki et al[52], 2015	Cross-sectional study	133 patients with IBD	Serum 25(OH)D levels	UC, CD	No difference regarding health-related quality of life between patients with deficient and sufficient VD
Dan et al[53], 2022	Prospective cohort study	5222 patients with IBD 529 deaths	Serum 25(OH)D levels	UC, CD	Nonlinear correlation was observed between VD concentrations and overall mortality
Johansen et al[54], 2023	Prospective cohort study	573 patients with IBD	Serum 25(OH)D levels	UC, CD	VD deficiency is the only factor related with impaired energy cluster (lack of energy, feeling drowsy, difficulty in sleeping)
Ananthakrishnan et al[55], 2014	Multi-institutional cohort study	2089 patients with IBD	Serum 25(OH)D levels	UC, CD	Patients with IBD with VD deficiency has an increased risk of developing colorectal cancer
Abraham et al[61], 2023	Retrospective cohort study	88 patients with IBD	Pretreatment 25(OH)D levels	UC, CD	Higher pre-treatment VD levels were linked with profound endoscopic improvement in patients with UC. Regarding CD patients, those with high pre-treatment VD levels had significantly higher vedolizumab levels after treatment
Chanchlani et al[62], 2023	Prospective cohort study	1107 patients with IBD	Pretreatment 25(OH)D levels	CD	Pretreatment VD concentration is not associated with primary non-response to anti-tumor necrosis factor treatment at week 14 or non-remission at week 54
Sninsky et al[64], 2025	Retrospective cohort study	5021 patients with IBD	VD supplement	UC, CD	VD supplementation was linked to fewer IBD-related emergency department visits, hospitalizations, and corticosteroid use
Yin et al[66], 2022	Retrospective cross-sectional study	639 patients with IBD	VD supplement	UC, CD	Supplementation of VD is crucial in patients with high-risk of developing osteopenia and osteoporosis
Tulewicz-Marti et al[67], 2022	Prospective, one-centre study	187 patients with IBD	Serum 25(OH)D levels, VD supplement	UC, CD	Bone mineral alterations were common in patients with IBD, mostly in patients with CD. VD supplementation remains crucial, especially when taking corticosteroids
Stallhofer et al[69], 2022	Cross-sectional observational study	104 patients with IBD	Serum 25(OH)D levels	UC, CD	VD can improve iron deficiency in IBD contributing in higher iron absorption from the intestine
Wallace et al[70], 2023	Systematic review	22 randomized controlled trials, 1874 patients with IBD	VD supplement	UC, CD	Lesser clinical relapses observed when comparing VD with placebo, but there is no enough evidence to draw any conclusions on differences in clinical response, quality of life, or withdrawals
Zepeda et al[71], 2022	Narrative review	43 primary studies published from 2015 to 2020	VD supplement	UC, CD	VD administration above 2000 IU per day to inactive patients with inflammatory bowel disease, and higher doses (between 5000 IU per day and 10000 IU per day) to those in the active stage, could possibly benefit the disease
Li et al[72], 2025	Cross-sectional study	3591 subjects	VD supplement	UC, CD	Increased VD intake may reduce the risk of IBD
Sun et al[73], 2023	Systematic review and meta-analysis	16 papers	Serum 25(OH)D levels, VD supplement	UC, CD	No obvious relationship between pediatric IBD and VD was noticed. VD supplementation can improve disease activity

CD: Crohn’s disease; CD40 L: Cluster of differentiation ligand; CRP: C-reactive protein; FCP: Fecal Calprotectin; IBD: Inflammatory bowel diseases; UC: Ulcerative colitis; VD: Vitamin D.