A Clinical Trial to Investigate the Efficacy of Acacia Fiber on Gastrointestinal Health and Microbiota Composition in Healthy Adults With Occasional Constipation

A Randomized, Triple-Blind, Placebo Controlled, Parallel Clinical Trial to Investigate the Efficacy of Acacia Fiber on Gastrointestinal Health and Microbiota Composition in Healthy Adults With Occasional Constipation

The goal of this randomized blinded placebo-controlled clinical trial is to investigate the effect of low- and high-dose supplementation of Acacia fiber on gut health and microbiota composition in adults with occasional constipation in a controlled diet context. Acacia fiber is a soluble dietary fiber with prebiotic properties, and this study evaluates its role in modulating gut microbiota and associated gastrointestinal outcomes. Acacia fiber has previously demonstrated improvements in stool frequency in the context of an irritable bowel syndrome with constipation (IBS-C)-characterized population. The main questions this study aims to answer are: Does Acacia fiber supplementation (5 g or 10 g) improve the frequency of bowel movements or stool consistency (assessed by Bristol Stool Scale) in the context of healthy population with occasional constipation? Does Acacia fiber benefit on gut health correlates with specific gut microbiota modulation characterised by shotgun sequencing? What are mechanistical faecal & blood markers that may support this correlation? Researchers will compare low-dose Acacia fiber (5 g), high-dose Acacia fiber (10 g), and placebo to see if Acacia fiber modulates gut microbiota composition in a manner consistent with prebiotic activity and whether these changes are associated with improvements in bowel movement frequency and stool consistency. Participants will:

• Take a daily supplement of either 5 g Acacia fiber, 10 g Acacia fiber, or placebo
• Complete study diaries, including the Bowel Habits Diary and Bristol Stool Scale
• Complete the Patient Assessment of Constipation Quality of Life, modified Gastrointestinal Symptoms Rating Scale, and sleep and stress Likert scales
• Complete 3-day food records

Study Overview

• Status: Not yet recruiting
• Conditions: Gastrointestinal Health; Occasional Constipation; Gut Microbiota Composition
• Intervention / Treatment: Dietary supplement: Low-dose Acacia fiber; Dietary supplement: High-dose Acacia fiber; Dietary supplement: Placebo powder

• Study Type: Interventional
• Enrollment (Estimated): 105
• Phase: Not Applicable

Contacts and Locations

• Study Contact: Name: Erin Lewis, PhD; Phone Number: 248 1-226-242-4551; Email: elewis@kgkscience.com
• Study Contact Backup: Name: Damien Guillemet; Phone Number: +33 2 32 83 18 18; Email: d.guillemet@nexira.com

Study Locations

• Canada
  • Ontario
    • London, Ontario, Canada, N5Y 5V6
      • KGK Science Inc.

Participation Criteria

Eligibility Criteria

• Ages Eligible for Study: Adult
• Accepts Healthy Volunteers: Yes

Description

Inclusion Criteria:

• Males and females aged between 30 and 60 years old, inclusive
• Body Mass Index (BMI) between 18.5 to 29.9 kg/m², inclusive
• Stable body weight defined as a <5% change in body weight in the three months prior to baseline as assessed by the Qualified Investigator (QI)

• Participants must meet the following criteria of occasional constipation for the past 3 months. This will be assessed at screening and confirmed over a 2-week period prior to baseline:

  • 5 CSBMs per week AND either one of the following: at least 25% of Bowel Movements (BMs) are BSS type 1 or 2 OR straining for most of the BMs (≥50%), defined as 3 minutes or more during BM, as assessed by the QI

OR,

At least 50% of BMs are BSS type 1 and 2, as assessed by the QI

OR,

≤ 3 CSBMs per week as assessed by the QI

• Low to moderate fiber intake, defined as < 18 g per day for women and < 22 g per day for men, as assessed by the Food Frequency Questionnaire (FFQ)
• Females not of child-bearing potential, defined as those who have undergone a sterilization procedure (e.g. hysterectomy, bilateral oophorectomy, bilateral tubal ligation, complete endometrial ablation) or have been post-menopausal for at least 1 year prior to screening

OR,

Individuals of child-bearing potential must have a negative baseline urine pregnancy test and agree to use a medically approved method of birth control for the duration of the study. All hormonal birth control must have been in use for a minimum of three months. Acceptable methods of birth control include:

Hormonal contraceptives including oral contraceptives, hormone birth control patch (Ortho Evra), vaginal contraceptive ring (NuvaRing), injectable contraceptives (Depo-Provera, Lunelle), or hormone implant (Norplant System)

Double-barrier method

Intrauterine devices

Non-heterosexual lifestyle and agrees to use contraception if planning on changing to heterosexual partner(s)

Vasectomy of partner at least 6 months prior to screening

Abstinence and agrees to use contraception if planning on becoming sexually active during the study

• Agrees to maintain current lifestyle habits (diet, sleep, physical activity, medications, supplements, and without any new addition) as much as possible throughout the study
• Provided voluntary, written, informed consent to participate in the study
• Healthy as determined by medical history and laboratory results as assessed by the Qualified Investigator (QI)
• Willing and able to comply with the study protocol (e.g., concomitant treatment) and complete questionnaires, records and diaries associated with the study, as well as complete all clinic visits

Exclusion Criteria:

• Individuals who are pregnant, breast feeding, or planning to become pregnant during the study
• Allergy, sensitivity or intolerance, to study products
• Chronic constipation, as assessed by the QI
• Following a specific diet (e.g., vegetarian, paleo, ketogenic, carnivore)
• Colonoscopy within four weeks prior to baseline or during the study
• Gastrointestinal related sensitivities including gluten and lactose intolerance
• Current or history of any significant diseases of the gastrointestinal tract (e.g., irritable bowel syndrome, irritable bowel disease, gastrointestinal surgery) as assessed by the QI
• Unstable metabolic disease, autoimmune disease or chronic diseases as assessed by the QI
• Unstable hypertension. Treatment on a stable dose of medication for at least 3 months will be considered by the QI (See Section 8.3.1)
• Type I diabetes
• Type II diabetes if on insulin treatment. Type II diabetics on stable medication for at least three months and an Hemoglobin A1c (HbA1c) of <8.0% may be included after assessment by the QI on a case-by-case basis
• Significant cardiovascular event in the past 6 months. Participants with no significant cardiovascular event on stable medication may be included after assessment by the QI on a case-by-case basis
• History of or current diagnosis with kidney and/or liver diseases as assessed by the QI on a case-by-case basis, with the exception of history of kidney stones in participants who are symptom free for 6 months
• Self-reported confirmation of current or pre-existing thyroid condition. Treatment on a stable dose of medication for at least 3 months will be considered by the QI
• Major surgery in the past 3 months or individuals who have planned surgery during the course of the study. Participants with minor surgery will be considered on a case-by-case basis by the QI
• Cancer, except skin basal cell carcinoma completely excised with no chemotherapy or radiation with a follow up that is negative. Volunteers with cancer in full remission for more than five years after diagnosis are acceptable
• Individuals with an autoimmune disease or are immune compromised as assessed by the QI
• Self-reported confirmation of a Human Immunodeficiency Virus (HIV)-, Hepatitis B- and/or C-positive diagnosis as assessed by the QI
• Self-reported confirmation of blood/bleeding disorders as assessed by the QI
• Use of prescribed cannabinoid products
• Chronic use of cannabinoid products (>2 times/week). Occasional users will be required to washout for at least 60 days and abstain for the duration of the study period
• Regular use of tobacco or nicotine products within the past three years, as assessed by the QI.
• Alcohol intake average of >2 per day or >10 per week of standard drinks as assessed by the QI
• Alcohol or drug abuse within the last 12 months
• Current use of prescribed and/or over-the-counter (OTC) medications, supplements, and/or consumption of food/drinks that may impact the efficacy and/or safety of the investigational product, gut transit and/or constipation, or gut microbiota characteristics (e.g., fibre, pre- pro- postbiotic, polyphenols extract, etc.) (Section 8.3)
• Clinically significant abnormal laboratory results at screening as assessed by the QI
• Blood donation 30 days prior to baseline, during the study, or a planned donation within 30 days of the last study visit
• Participation in other clinical research studies 60 days prior to baseline, as assessed by the QI
• Individuals who are unable to give informed consent
• Any other condition or lifestyle factor, that, in the opinion of the QI, may adversely affect the participant's ability to complete the study or its measures or pose significant risk to the participant

Study Plan

How is the study designed?

Design Details

• Primary Purpose: Treatment
• Allocation: Randomized
• Interventional Model: Parallel Assignment
• Masking: Quadruple

Number of Arms

3

Arms and Interventions

Participant Group / Arm	Intervention / Treatment
Placebo Comparator: Placebo	Dietary supplement: Placebo powder; Starting the day following the baseline visit (Day 1), participants will take 1 sachet daily for 4 days, then increase to 2 sachets daily until the day prior to the end-of-study visit (Day 56). Each sachet will be mixed with a usual food or beverage prior to consumption.
Experimental: Low-dose Acacia fiber	Dietary supplement: Low-dose Acacia fiber; Starting the day following the baseline visit (Day 1), participants will take 1 sachet daily for 4 days, then increase to 2 sachets daily until the day prior to the end-of-study visit (Day 56). Each sachet will be mixed with a usual food or beverage prior to consumption.
Experimental: High-dose Acacia fiber	Dietary supplement: High-dose Acacia fiber; Starting the day following the baseline visit (Day 1), participants will take 1 sachet daily for 4 days, then increase to 2 sachets daily until the day prior to the end-of-study visit (Day 56). Each sachet will be mixed with a usual food or beverage prior to consumption.

What is the study measuring?

Primary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Frequency of complete and spontaneous bowel movements	Frequency of complete and spontaneous bowel movements (CSBMs), as assessed by the Bowel Habits Diary (BHD)	Baseline to Day 56
Stool consistency	Stool consistency, as assessed by the Bristol Stool Scale (BSS). The BSS is a 7-item stool description and image scale that assesses the shape and consistency of stool. Scores range from 1 to 7, with higher scores indicating looser stool consistency and lower scores indicating harder stool consistency.	Baseline to Day 56

Secondary Outcome Measures

Outcome Measure	Measure Description	Time Frame
Gut Microbiota Composition	Change from baseline to Day 56 between Acacia fiber (5g or 10g) and placebo in gut microbiota composition, as assessed by fecal microbiome shotgun sequencing	Baseline to Day 56
Frequency of CSBMs	Change from baseline to Day 28 between Acacia fiber (5g or 10g) and placebo in frequency of CSBMs, as assessed by the BHD	Baseline to Day 28
Stool Consistency	Change from baseline to Day 28 between Acacia fiber (5g or 10g) and placebo in stool consistency, as assessed by the Bristol Stool Scale (BSS). The BSS is a 7-item stool description and image scale that assesses the shape and consistency of stool. Scores range from 1 to 7, with higher scores indicating looser stool consistency and lower scores indicating harder stool consistency.	Baseline to Day 28
Digestive symptoms	Change from baseline to Day 28 and Day 56 between Acacia fiber (5g or 10g) and placebo in digestive symptoms as assessed by Gastrointestinal Symptom Rating Scale (GSRS). The modified GSRS consists of 14 items on a four-point scale (0-3). It assesses abdominal pain, reflux syndrome, diarrhea syndrome, indigestion syndrome, and constipation syndrome. Higher scores indicate more severe gastrointestinal symptoms.	Baseline to Day 28 and Day 56
Patient Assessment of Constipation Quality of Life questionnaire (PAC-QoL)	Change from baseline to Day 28 and Day 56 between Acacia fiber (5g or 10g) and placebo in Quality of life as assessed by Patient Assessment of Constipation Quality of Life questionnaire (PAC-QoL). The PAC-QoL consists of 28-items with four subscales (worries and concerns, physical discomfort, psychosocial discomfort, and satisfaction), and an overall scale. Items are scored on a 5-point Likert scale ranging from 0 to 4, with lower scores indicating better constipation-related quality of life.	Baseline to Day 28 and Day 56
Proportion of CSBMs with complete defecation	The difference in the proportion of CSBMs with complete defecation at Day 28 and Day 56 between Acacia fiber (5g or 10g) and placebo	Day 28 and Day 56
proportion of participants with occasional constipation	The difference in the proportion of participants with occasional constipation at Day 56 between Acacia fiber (5g or 10g) and placebo	Day 56
Sleep and Stress	Change from baseline to Day 28 and Day 56 between Acacia fiber (5g or 10g) and placebo in sleep and stress, as assessed by the sleep and stress Likert scales. Four-point Likert scales will be used to measure the participant's perceived sleep quality (strongly disagree - 0, disagree - 1, agree - 2, strongly agree - 3) and stress (no stress - 0, minimally stressed - 1, moderately stressed - 2, extremely stressed - 3). Participants will be instructed to indicate their response on the scale for the following statements: "Overall, I am satisfied with my sleep" and " Rate your current stress level". Higher scores indicate greater perceived stress.	Baseline to Day 28 and Day 56

Other Outcome Measures

Outcome Measure	Measure Description	Time Frame
Change from baseline to Day 28 between Acacia fiber (5g or 10g) and placebo in gut microbiota composition, as assessed by fecal microbiome shotgun sequencing	Change from baseline to Day 28 between Acacia fiber (5g or 10g) and placebo in gut microbiota composition, as assessed by fecal microbiome shotgun sequencing	Baseline to Day 28
Change from baseline to Day 28 and Day 56 between Acacia fiber (5g or 10g) and placebo in short-chain fatty acids (SCFAs)	Change from baseline to Day 28 and Day 56 between Acacia fiber (5g or 10g) and placebo in constipation related fecal biomarkers (short-chain fatty acids (SCFAs).	Baseline to Day 28 and Day 56
Change from baseline to Day 28 and Day 56 between Acacia fiber (5g or 10g) and placebo in lipopolysaccharides (LPS) and LPS binding proteins	Change from baseline to Day 28 and Day 56 between Acacia fiber (5g or 10g) and placebo in constipation related fecal biomarkers (lipopolysaccharides (LPS) and LPS binding proteins).	Baseline to Day 28 and Day 56
Change from baseline to Day 28 and Day 56 between Acacia fiber (5g or 10g) and placebo in primary and secondary bile acids	Change from baseline to Day 28 and Day 56 between Acacia fiber (5g or 10g) and placebo in constipation related fecal biomarkers (primary and secondary bile acids).	Baseline to Day 28 and Day 56
Change from baseline to Day 28 and Day 56 between Acacia fiber (5g or 10g) and placebo in fecal serotonin	Change from baseline to Day 28 and Day 56 between Acacia fiber (5g or 10g) and placebo in constipation related fecal biomarkers (serotonin).	Baseline to Day 28 and Day 56
Change from baseline to Day 28 and Day 56 between Acacia fiber (5g or 10g) and placebo in Immunoglobulin A	Change from baseline to Day 28 and Day 56 between Acacia fiber (5g or 10g) and placebo in constipation related fecal biomarkers (Immunoglobulin A).	Baseline to Day 28 and Day 56
Change from baseline to Day 56 between Acacia fiber (5g or 10g) and placebo in plasma short-chain fatty acid (SCFA) concentrations	Change from baseline to Day 56 between Acacia fiber (5g or 10g) and placebo in constipation related blood biomarkers (SCFAs)	Baseline to Day 56
Change from baseline to Day 56 between Acacia fiber (5g or 10g) and placebo in plasma lipopolysaccharide (LPS) concentrations	Change from baseline to Day 56 between Acacia fiber (5g or 10g) and placebo in constipation related blood biomarkers (LPS)	Baseline to Day 56
Change from baseline to Day 56 between Acacia fiber (5g or 10g) and placebo in plasma zonulin	Change from baseline to Day 56 between Acacia fiber (5g or 10g) and placebo in constipation related blood biomarkers (zonulin)	Baseline to Day 56
Change from baseline to Day 56 between Acacia fiber (5g or 10g) and placebo in plasma serotonin	Change from baseline to Day 56 between Acacia fiber (5g or 10g) and placebo in constipation related blood biomarkers (serotonin)	Baseline to Day 56
Change from baseline to Day 56 between Acacia fiber (5g or 10g) and placebo in plasma motilin	Change from baseline to Day 56 between Acacia fiber (5g or 10g) and placebo in constipation related blood biomarkers (motilin)	Baseline to Day 56
Incidence of post-emergent adverse events (AE)	Incidence of post-emergent adverse events (AE)	From screening (Day -45 to Day -15) through final study visit (Visit 4)
Clinically relevant changes in blood pressure after supplementation	Changes in blood pressure (mmHg) after supplementation	From screening (day -45 to day -15) through final study visit (visit 4)
Change in complete blood count following supplementation	Clinically relevant changes in complete blood count after supplementation	At screening (day -45 to day -15) and visit 4 (day 56)
Change in plasma aspartate aminotransferase (AST) concentration following supplementation	Clinically relevant changes in clinical chemistry (aspartate aminotransferase (AST)) after supplementation	At screening (day -45 to day -15) and visit 4 (day 56)
Change in plasma alanine aminotransferase (ALT) concentration following supplementation	Clinically relevant changes in clinical chemistry (alanine aminotransferase (ALT)) after supplementation	At screening (day -45 to day -15) and visit 4 (day 56)
Change in plasma alkaline phosphatase (ALP) concentration following supplementation	Clinically relevant changes in clinical chemistry (alkaline phosphatase (ALP)) after supplementation	At screening (day -45 to day -15) and visit 4 (day 56)
Change in total bilirubin following supplementation	Clinically relevant changes in total bilirubin after supplementation	At screening (day -45 to day -15) and visit 4 (day 56)
Change in creatinine following supplementation	Clinically relevant changes in creatinine after supplementation	At screening (day -45 to day -15) and visit 4 (day 56)
Change in estimated glomerular filtration rate (eGFR) following supplementation	Clinically relevant changes in estimated glomerular filtration rate (eGFR) after supplementation	At screening (day -45 to day -15) and visit 4 (day 56)
Change in potassium following supplementation	Clinically relevant changes in serum potassium after supplementation	At screening (day -45 to day -15) and visit 4 (day 56)
Change in sodium following supplementation	Clinically relevant changes in serum sodium after supplementation	At screening (day -45 to day -15) and visit 4 (day 56)
Change in chloride following supplementation	Clinically relevant changes in serum chloride after supplementation	At screening (day -45 to day -15) and visit 4 (day 56)
Clinically relevant changes in heart rate after supplementation	Changes in heart rate (beats per minute) after supplementation	From screening (day -45 to day -15) through final study visit (visit 4)

Collaborators and Investigators

• Sponsor: Nexira
• Collaborators: KGK Science Inc.
• Investigators: Principal Investigator: David Crowley, MD, KGK Science Inc.

Study record dates

Study Major Dates

• Study Start (Estimated): July 1, 2026
• Primary Completion (Estimated): December 1, 2026
• Study Completion (Estimated): December 1, 2026

Study Registration Dates

• First Submitted: July 6, 2026
• First Submitted That Met QC Criteria: July 10, 2026
• First Posted (Actual): July 14, 2026

Study Record Updates

• Last Update Posted (Actual): July 14, 2026
• Last Update Submitted That Met QC Criteria: July 10, 2026
• Last Verified: July 1, 2026

More Information

Terms related to this study

• Keywords: prebiotic; microbiota; gut health; gum acacia; acacia fiber
• Other Study ID Numbers: FIB16 / 25NXCRR01

Drug and device information, study documents

• Studies a U.S. FDA-regulated drug product: No
• Studies a U.S. FDA-regulated device product: No