Efficacy of Microencapsulated Sodium Butyrate as Add-On Therapy in Inducing Remission in Patients with Mild-To-Moderate Ulcerative Colitis: Results From a Multi-Center, Double-Blind, Randomized, Placebo-Controlled Study

Introduction

Inflammatory bowel disease (IBD), including ulcerative colitis (UC) and Crohn’s disease (CD), comprises chronic autoimmune conditions of the gastrointestinal tract with alternating remission and exacerbation [1–4]. UC presents with persistent diarrhea, abdominal pain, fatigue, joint pain, fever, and weight loss, significantly impairing quality of life. Its global prevalence is rising, reaching 120 to 505 per 100 000 individuals, especially in North America and Europe [5]. Onset typically occurs between ages 15 and 35 years, during peak years of professional and social activity, leading to personal and socioeconomic consequences such as reduced productivity, frequent sick leave, and high healthcare costs, particularly in patients who require long-term pharmacotherapy, hospitalization, or surgery due to inadequate response to conventional treatment [6,7].

The pathogenesis of IBD is multifactorial, involving complex interactions between genetic, immune, environmental, and microbiota-related factors [8–11]. Growing evidence suggests that intestinal dysbiosis plays a key role in the development and activity of the disease. Consequently, microbiota-targeted therapies, including probiotics and prebiotics, are being explored as adjuncts to reduce inflammation and to enhance mucosal barrier function [12,13]. Moreover, given the limitations of standard and advanced pharmacotherapies, including variable efficacy, high costs, and the potential for adverse effects, interest in microbiota-modulating strategies as supportive treatments in UC is increasing [14].

Among microbiota-derived metabolites, short-chain fatty acids (SCFAs), particularly butyric acid, have attracted growing interest. Butyrate is a key energy source for colonocytes and is essential for epithelial barrier integrity, immune regulation, and gut homeostasis [15,16]. Although it comprises only 15% of SCFAs (compared to 60% acetic and 25% propionic acid), butyrate exerts disproportionately strong effects on mucosal biology [17]. It enhances epithelial tight junction function, promotes mucus secretion and epithelial regeneration, promotes angiogenesis, and helps maintain a healthy intestinal pH. It also suppresses pro-inflammatory signaling via inhibition of nuclear factor-κB (NF-κB), and modulates leukocyte recruitment by downregulating the expression of cytokines, chemokines, and adhesion molecules [18–20]. In addition to its barrier-preserving and immunomodulatory functions, MSB shows antisecretory and proabsorptive properties, including inhibition of chloride secretion via Na-K-2Cl cotransporter (NKCC1) and stimulation of sodium absorption, which may further contribute to symptomatic relief in UC [21]. These mechanisms are particularly relevant in UC, where chronic inflammation and epithelial damage result from both immune dysregulation and metabolic imbalance.

Butyric acid is primarily produced in the colon by sugar-fermenting bacteria (eg, Clostridium spp., Eubacterium spp., Butyrivibrio spp.) through fermentation of indigestible complex carbohydrates and hexose oligomers. About 95% of SCFAs are absorbed by intestinal epithelial cells and serve as energy sources and immune regulators; only 5% are excreted. Dietary sources include resistant starch, oligosaccharides (eg, inulin), disaccharides (eg, lactose), and sugar alcohols (eg, sorbitol). The most effective precursors are resistant starch-rich foods like oats, wheat bran, raw potatoes, green bananas, and certain vegetables. However, many of these foods irritate the gut mucosa in IBD patients, and their restriction can reduce substrate availability, leading to decreased butyrate production and potential deficiencies. Additionally, IBD is associated with impaired butyrate transport and mucosal metabolism, limiting its physiological availability [15,22].

It is also important to emphasize that IBD is associated with significant quantitative and qualitative alterations in the gut microbiota, reducing the capacity to synthesize SCFAs, particularly butyrate. A hallmark of this dysbiosis is a marked deficiency of Firmicutes, especially the Clostridium coccoides and Clostridium leptum groups, which are the main SCFA producers. Their depletion is associated with reduced luminal butyrate levels, which can contribute to intestinal inflammation in IBD [23].

Given the wide range of physiological benefits of butyrate, including its role in barrier integrity, immune modulation, and mucosal homeostasis, maintaining its adequate intestinal levels is crucial. While in healthy individuals a well-balanced diet may be sufficient, IBD patients require significantly higher amounts of butyrate to support epithelial repair and mucosal regeneration. In such cases, targeted butyrate supplementation becomes essential to meet these increased demands.

Natural butyrate supplementation is challenging due to its instability and unfavorable properties such as unpleasant taste and smell. Unprotected butyrate is rapidly absorbed in the upper GI tract, limiting its availability in the distal colon, where UC inflammation is typically most active. To address this, microencapsulated sodium butyrate (MSB) has been developed. MSB formulations like Debutir forte® protect butyrate from early degradation and enable controlled release in the distal intestine, increasing local bioavailability and therapeutic efficacy [24].

Recent clinical evidence increasingly supports the potential therapeutic role of MSB in the management of ulcerative colitis (UC). In a 12-month observational study by Vernero et al, MSB added to mesalamine significantly improved clinical and biochemical outcomes in patients in remission. It reduced fecal calprotectin and residual symptoms, highlighting its potential not only as maintenance therapy but also as a microbiota-modulating agent capable of promoting mucosal healing and sustaining long-term remission [25].

Despite promising evidence, a clear research gap exists regarding MSB use for remission induction in active UC. No high-quality, randomized, placebo-controlled trials have yet evaluated its therapeutic efficacy in this context. To address this research gap, the present study was designed as a multi-center, double-blind, randomized, placebo-controlled trial to assess the efficacy, safety, and therapeutic potential of MSB as an add-on therapy in patients with mild-to-moderate active UC.

Material and Methods

STUDY DESIGN:

We conducted a multi-center, double-blind, randomized, placebo-controlled study to evaluate the efficacy and safety of microencapsulated sodium butyrate (Debutir forte^®, Polpharma) as an add-on therapy in patients with mild-to-moderate UC. Ethics approval was obtained from the Ethics Committee of the National Medical Institute of the Ministry of the Interior and Administration in Warsaw (Approval code: 35/2020; Date of approval: March 4, 2020).

PARTICIPANTS:

From April 2021 to April 2023, participants were recruited from among UC patients referred to the Department of Gastroenterology and Internal Medicine at the National Medical Institute of the Ministry of the Interior and Administration in Warsaw and the Department of Digestive Tract Diseases at the Medical University of Łódź. Recruitment was conducted by gastroenterologists from these departments. Patients with mild-to-moderate UC, defined by a Total Mayo Score (TMS) between 3 and 10 points, were eligible. Participants were aged 18 years and older, with disease confirmed through endoscopic and histological examinations based on guidelines from the Polish Society of Gastroenterology and the European Crohn’s and Colitis Organisation at least 1 year before the study. Written informed consent was obtained from all participants. They were required to be on stable UC therapy, with no changes in medication type or dose.

Exclusion criteria included UC limited to the rectum (proctitis – E1 in the Montreal classification), recent escalation of treatment or addition of another therapy within 24 weeks before the study, use of antibiotics, pro-/pre-/synbiotics, SCFAs, or other supplements within 12 weeks, significant changes in diet and lifestyle, diagnosis of COVID-19 during or within 8 weeks before the study, other gastrointestinal diseases, history of colostomy or cancer, hospitalization during the study, pregnancy, lactation, and refusal to participate.

RANDOMIZATION, ALLOCATION CONCEALMENT, AND BLINDING:

Eligible patients were randomly assigned to either the intervention or placebo group in a 1: 1 ratio using block randomization and a random number generator. We used block randomization to ensure balanced allocation of patients to different study arms, which was particularly important in this study due to the sample size. The study was conducted in a double-blind manner. A statistician not involved in the study performed the randomization, and allocation concealment was ensured by use of sequentially numbered opaque envelopes, which were opened in order upon patient admission. Throughout the trial, researchers, participants, and laboratory personnel remained blinded to the supplement assignments. The blinding was maintained until the study database was locked, minimizing the risk of performance and detection bias.

INTERVENTIONS AND STUDY PROCEDURE:

Two visits were conducted during the 8-week study period: V1 (the baseline visit), and V2 (the end-of-treatment visit). At the initial visit (V1), participants were provided with detailed verbal and written information regarding the study protocol. They were also asked to review and sign the Informed Consent Form and the Declaration of Consent for the Processing of Personal Data related to study participation.

Following consent, baseline disease activity was assessed through a comprehensive clinical evaluation, including a structured medical interview and physical examination. In addition, participants underwent laboratory investigations (blood and stool analyses) and flexible sigmoidoscopy to objectively evaluate inflammatory activity and establish baseline clinical, biochemical, and endoscopic parameters.

Subsequently, participants were randomized in a 1: 1 ratio to intervention or placebo group (in line with the previously described procedures). The intervention group received 300 mg of microencapsulated sodium butyrate (MSB) twice daily for 8 weeks. The control group received 300 mg of rice starch capsules twice daily for 8 weeks as a placebo. Placebo capsules were indistinguishable from active capsules in shape, size, and color. Both MSB, which contained sodium butyrate, hydroxypropyl methylcellulose, and sodium alginate, and placebo were provided by Polpharma. Participants were instructed to maintain their regular eating habits.

At visit 2, conducted after 8 weeks, a follow-up clinical interview was performed to assess the severity of disease symptoms. A physical examination was carried out, and blood and stool samples were collected for laboratory testing. Additionally, a flexible sigmoidoscopy was performed to evaluate endoscopic disease activity. Treatment adherence to supplementation was concurrently assessed by counting returned supplements, with adherence defined as consuming at least 90% of the provided supplements. In addition, participants were instructed to record each dose taken in a medication diary, which was reviewed at visit 2 to support adherence monitoring. Participants were also asked to return used supplement containers, which were checked to verify whether any doses had been missed.

Adverse events were systematically monitored throughout the study period. At each study visit, participants were actively asked about any new or ongoing symptoms, and all adverse events (AEs) were documented in standardized case report forms. The severity, duration, and potential relation to the intervention were assessed by the study physician. Serious adverse events (SAEs) were immediately reported to the study sponsor and ethics committee in accordance with regulatory guidelines. All recorded events were reviewed and analyzed descriptively in the final data analysis.

PRIMARY AND SECONDARY ENDPOINTS:

Primary endpoints included clinical improvement (TMS reduction ≥3 points), clinical remission (TMS ≤2, stool frequency subscore ≤1, rectal bleeding subscore of 0, endoscopic subscore ≤1 without friability), endoscopic improvement (one-degree reduction in endoscopic score), endoscopic remission (Mayo score 0), and biochemical remission (fecal calprotectin ≤250 μg/g).

Secondary endpoints included improvements in biochemical parameters (butyric acid [C4] concentration in stool, fecal calprotectin, C-reactive protein, erythrocyte sedimentation rate [ESR], hemoglobin [Hb], ferritin, albumin, total protein, and vitamin D3) 8 weeks after enrolment.

EVALUATION OF BUTYRIC ACID (C4) CONCENTRATION:

C4 concentration was evaluated by mass spectrometry. Freshly thawed fecal samples (60 mg) were dissolved in 300 μl of methanol, vortexed, treated with ultrasound, and centrifuged. Supernatants were stored at −80°C until analysis. Samples were analyzed using a TripleTof^® 6600+ with an Acquity UPLC HSS T3 (C18) column. Separation was carried out using a gradient of water and methanol buffers containing 0.04% formic acid. Ionization occurred with electrospray (ESI) at 3500 V, using nitrogen as the atomizing and drying gas. Data analysis was performed with XCMSplus.

EVALUATION OF BIOCHEMICAL PARAMETERS:

The biochemical parameters assessed in the study were measured using laboratory methods, namely: fecal calprotectin was determined by chemiluminescence assay, C-reactive protein was measured using latex-enhanced immunoturbidimetric assay, erythrocyte sedimentation rate (ESR) was assessed by photometric kinetic analysis in a capillary system, hemoglobin (Hb) was measured photometrically using sodium lauryl sulphate, ferritin was quantified by electrochemiluminescence immunoassay, albumin was determined by colorimetric method using bromocresol green, total protein was measured by biuret colorimetric assay, and vitamin D3 was assessed using chemiluminescence immunoassay.

STATISTICAL ANALYSIS:

The analysis was conducted using R (version 4.1.2). The study group characteristics were based on the 107 patients initially included. Further analysis was performed on 98 patients due to missing disease activity data from Visit 2 for 9 patients. Numeric variables are described using the mean and standard deviation or the median and interquartile range, depending on the normality of the data. Categorical variables are presented with counts and percentages for each group. Comparisons between the MSB and Placebo groups were conducted using the t test, the Mann-Whitney U test, Pearson’s chi-square test, or Fisher’s exact test, as appropriate. Effect sizes are presented as mean or median differences for numeric variables or Cramer’s V coefficient for categorical variables. Comparisons between Visit 1 and Visit 2 were performed using paired t tests, Wilcoxon’s tests, McNemar’s tests, or Friedman’s tests, as appropriate. Correlations were assessed using Spearman’s method due to the non-normal distribution of some variables. All statistical calculations assumed an alpha level of 0.05.

Results

PRIMARY ENDPOINTS:

In the intention-to-treat (ITT) analysis, significant differences were observed for clinical improvement (P=0.001), clinical remission (P=0.001), endoscopic improvement (P=0.004), and biochemical remission (P=0.005), all favoring the MSB group. Clinical improvement was noted in 26 patients (48.1%) in the MSB group compared to 10 (18.9%) in the placebo group (P=0.001). Clinical remission was achieved in 16 patients (29.6%) in the MSB group versus 3 (5.7%) in the placebo group (P=0.001). Endoscopic improvement was seen in 12 patients (22.2%) in the MSB group compared to 2 (3.77%) in the placebo group (P=0.004). Biochemical remission was confirmed in 21 patients (38.9%) in the MSB group versus 8 (15.0%) in the placebo group (P=0.005).

In the per-protocol (PP) analysis, significant differences were also noted for clinical improvement (P=0.005), clinical remission (P=0.004), endoscopic improvement (P=0.006), and biochemical remission (P=0.009), all favoring the MSB group. Clinical improvement was achieved in 26 patients (51%) in the MSB group compared to 10 (21.3%) in the placebo group (P=0.005). Clinical remission was found in 16 patients (31.4%) in the MSB group versus 2 (6.4%) in the placebo group (P=0.004). Endoscopic improvement was confirmed in 12 patients (25.5%) in the MSB group compared to 2 (4.6%) in the placebo group (P=0.006). Biochemical remission was observed in 21 patients (41.2%) in the MSB group versus 8 (17.0%) in the placebo group (P=0.009). No significant difference was found for endoscopic remission, with 6 patients (11.8%) in the MSB group versus 1 (2.1%) in the placebo group (P=0.114). All data are presented in Table 2. In the MSB group, significant changes from Visit 1 to Visit 2 were found for Endoscopic Mayo Score and TMS (P<0.001). In the placebo group, significant changes were also found for Endoscopic Mayo Score and TMS (P=0.008 and P=0.001, respectively). Detailed characteristics of each variable are presented in Table 3.

SECONDARY ENDPOINTS:

Significant changes were observed in the MSB group, including increases in C4 concentration (P<0.001), hemoglobin (Hb) in males (P=0.016), albumin (P=0.002), and vitamin D3 (P=0.001), along with decreases in fecal calprotectin (P<0.001) and erythrocyte sedimentation rate (ESR) (P=0.008). In the MSB group, C4 concentration increased by 3.43 nM/mg, while it decreased by 0.47 nM/mg in the placebo group (P<0.001 for both). All laboratory parameters are shown in Table 4.

CORRELATION ANALYSIS:

We estimated the correlation of final C4 concentration or change in C4 concentration during the intervention period in the MSB group with changes in TMS and Endoscopic Mayo Score. A strong positive correlation was found between the change in C4 concentration and TMS change (rho=0.80, P=0.003) among patients in clinical remission in the MSB group, indicating that a higher C4 change was strongly associated with a higher TMS change. Similarly, a strong positive correlation was observed between the change in C4 concentration and Mayo Score (MS) change (rho=0.87, P=0.001) among patients in clinical remission in the MSB group. Finally, a strong positive correlation was found between C4 concentration at Visit 2 and MS change among patients in clinical remission in the MSB group (rho=0.71, P=0.014), indicating that higher C4 levels at Visit 2 were strongly associated with higher MS change. Detailed data are presented in Table 5 and Figures 2, 3.

Discussion

STRENGTHS AND LIMITATIONS OF THE STUDY:

The study’s strengths include its randomized, double-blind, placebo-controlled design and quantification of fecal butyric acid. The demonstrated improvement in clinical, endoscopic, and inflammatory parameters supports MSB as a promising therapeutic adjunct. However, limitations include the short duration (8 weeks), lack of histopathological and microbiome analyses, absence of quality-of-life assessments, and non-blinded endoscopic evaluation. These areas should be addressed in future trials to fully elucidate MSB’s long-term efficacy and mechanisms of action.

Conclusions

In this randomized, double-blind, placebo-controlled trial, supplementation with microencapsulated sodium butyrate (MSB) resulted in significant clinical improvement, clinical remission, endoscopic improvement, and biochemical remission in patients with mild-to-moderate active ulcerative colitis (UC). These therapeutic effects were accompanied by an increase in fecal butyric acid (C4) concentrations, which were positively correlated with clinical, biochemical, and endoscopic outcomes. These findings suggest that fecal SCFA levels – particularly butyric acid – not only reflect but also potentially mediate treatment response.

When administered as an adjunct to stable mesalazine therapy, MSB demonstrated both efficacy and a favorable safety profile. Further studies are needed to determine whether a specific high level of butyric acid or a significant change in its concentration is necessary to induce remission and to assess the potential for mucosal healing with longer MSB administration.

Collectively, the present results, in conjunction with existing evidence, support the clinical utility of microencapsulated butyrate as an adjunctive treatment in UC, particularly in patients ineligible for biologic therapies or those requiring long-term, well-tolerated interventions. Given its excellent tolerability and lack of systemic immunosuppressive effects, MSB may be a viable addition to current therapeutic algorithms, particularly in early-stage or treatment-refractory disease. Nevertheless, further research is warranted to determine whether achieving a defined threshold (a specific high level of butyric acid) or relative increase in fecal butyrate is required to induce remission, as well as to assess the potential for mucosal healing with extended MSB administration. Future studies should aim to assess histologic remission, microbial compositional changes, and patient-reported outcomes to further elucidate MSB’s role in the integrated management of inflammatory bowel disease.