VITAMINS & SUPPLEMENTS · GUIDE
Partially Hydrolyzed Guar Gum, Acacia, Wheat Dextrin and Other Soluble Fibers
Partially hydrolyzed guar gum, acacia fiber, wheat dextrin and other soluble fibers: what each category is, what trials found, how they differ from psyllium, and cautions.
Content last updated . This page has not been medically reviewed.
Back to Probiotics & Gut SupportQuick answer
These are soluble fibers sold as powders or added to foods and drinks. They differ in how thick they are and how readily gut bacteria ferment them, so one fiber's results do not apply to another. Trials are mostly small and short. Partially hydrolyzed guar gum (PHGG) has the most support in one specific setting, diarrhea in people fed through a tube in hospital. This page names fiber categories only, not products, and is information only, not medical advice.
What each category is
- Partially hydrolyzed guar gum (PHGG) is made by partly breaking down guar gum with an enzyme. A review describes it as a soluble, highly fermentable fiber with low viscosity. [1]
- Acacia fiber is a soluble fiber studied in IBS and constipation trials. [2]
- Wheat dextrin and other resistant dextrins are made from partially broken-down starch. A 2022 review groups soluble corn fiber, resistant dextrin and wheat dextrin together as soluble, fermentable, nonviscous fibers. [3]
- Others named in the trials we read include pectin, agave fructans and nopal fiber. [4]
For psyllium, see psyllium and fiber supplements; for inulin, see the inulin page; for the thick-versus-fermentable idea, see soluble vs insoluble and fermentable vs non-fermentable fiber.
Evidence labels used here
Promising but limited, mixed, insufficient evidence, Proper evidence not found (we searched and read nothing usable). Changes in stool form or bacteria counts are markers, not proof of symptom relief.What trials and reviews found
| Fiber | Question | What the source found | Label |
|---|---|---|---|
| PHGG | Tube-feeding diarrhea | A 2022 meta-analysis of 16 trials found fiber lowered diarrhea risk in hospital patients on enteral nutrition (risk ratio 0.64). PHGG (2 trials) and mixed fiber were the types with a significant effect. [5] | Promising but limited (hospital setting) |
| PHGG | Constipation in care-home residents | In 52 residents with chronic constipation (average age 83.9), a daily PHGG drink for 4 weeks did not change stool frequency or form, but laxative use was lower in weeks 3 and 4. [6] | Mixed |
| PHGG | Loose stools in healthy volunteers | In 44 volunteers with loose-stool tendency, 3 months of PHGG improved stool form but not frequency, and increased Bifidobacterium. [7] | Promising but limited |
| PHGG | Gut transit | In a crossover test of healthy participants, a 20 g PHGG meal reduced small-intestinal transit compared with placebo. [8] | Insufficient evidence (physiology study) |
| PHGG plus acacia | Functional constipation | In 61 adults over 21 days, a PHGG-and-acacia formulation increased complete spontaneous bowel movements, and a follow-up found lower species richness in the gut microbiota. [9] | Mixed |
| Acacia fiber | IBS with constipation | In 180 adults over 4 weeks, acacia fiber improved stool frequency versus placebo; stool consistency, mass and quality of life did not change significantly. [2] | Promising but limited |
| Wheat dextrin | Laxative effect | A narrative review says wheat dextrin is nonviscous and fermentable, has no laxative effect, and that some fibers, including wheat dextrin, can be constipating. [10] | Insufficient evidence (review, not a trial) |
| Pectin, nopal, agave | Functional bowel disorders | A 2026 systematic review of 10 small, short trials reported mixed results by fiber: pectin powder improved pain and bloating, nopal fiber improved severity, agave fructans worsened flatulence. [4] | Mixed |
Wheat dextrin trials for constipation or IBS: Proper evidence not found. We searched PubMed for wheat dextrin with stool, bowel and constipation outcomes and read no trial.
Tolerance
The 2022 review of 103 trials in adults without gut disease said tolerance is specific to each fiber. For resistant maltodextrin and dextrin, up to 12 g a day was well tolerated in the trials, 12 to 27 g a day caused mild or moderate symptoms, and more than 50 g a day caused excessive flatulence and mild abdominal pain. [3] These are study amounts for that group, not advice. The reviews of PHGG we read did not give a tolerance figure we could quote.Related
Prebiotic fibers overview and fiber supplements compared.Frequently asked questions
What is partially hydrolyzed guar gum?
Guar gum partly broken down by an enzyme; it is soluble, highly fermentable and low in viscosity. [1]
Does PHGG help constipation?
Results are mixed: one trial found less laxative use but no change in stool frequency; a formulation with acacia increased complete bowel movements. [6][9]
Does acacia fiber work?
In a 4-week trial in IBS with constipation, acacia fiber improved stool frequency versus placebo, but not consistency or quality of life. [2]
Is wheat dextrin a laxative?
A narrative review says it has no laxative effect and can be constipating, but we found no trial. [10]
Are these fibers prebiotics?
Not automatically. ISAPP says not all dietary fibers are prebiotics and requires a documented benefit. [13]
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.
Safety and who should ask first
- Tube feeding and hospital use. Fiber in tube feeds is a clinician decision, not a home supplement choice.
- Medicines. Interaction data for these fibers: Proper evidence not found in what we read. Ask a pharmacist; see how interactions work.
- Bowel disease or blockage, swallowing difficulty. The NHS lists Crohn's disease, ulcerative colitis, bowel blockage and difficulty swallowing among reasons to check before laxatives. [11] See fiber and prebiotic cautions.
- Pregnancy, breastfeeding and children. The NHS says to check with a pharmacist or doctor if pregnant or breastfeeding, and that children can take laxatives if a GP recommends it. [11]
- Wheat and celiac disease. Whether wheat-derived dextrin is suitable for celiac disease or wheat allergy is not described in the sources we read; check the label and ask a clinician.
- Kidney, liver and surgery. Not described in the sources we read for these fibers. Ask a clinician; see supplements before surgery.
- Product quality and blends. Many products mix several fibers. See quality testing and certifications and comparing supplement labels.
- See a GP for constipation with blood in the stool or unintended weight loss. [12]
References
- Nutr Hosp 2017 [[Clinical utility of partially hydrolyzed guar gum: review of evidence and experience]](https://pubmed.ncbi.nlm.nih.gov/28244794/). PubMed abstract Read 2026-10-23.
- Eur J Nutr 2024 Acacia fiber or probiotic supplements to relieve gastrointestinal complaints in patients with constipation-predominant IBS: a 4-week randomized double-blinded placebo-controlled intervention trial. PubMed abstract Read 2026-10-23.
- Adv Nutr 2022 (PubMed abstract and open-access full text, PMC9776669) Gastrointestinal Effects and Tolerance of Nondigestible Carbohydrate Consumption. PubMed abstract Read 2026-10-23.
- Clinical Nutrition ESPEN 2026 Fibre manipulation to manage symptom severity and quality of life in patients with functional bowel disorders: A systematic review. PubMed abstract Read 2026-10-23.
- Front Nutr 2022 The effect of fiber supplementation on the prevention of diarrhea in hospitalized patients receiving enteral nutrition: A meta-analysis of randomized controlled trials with the GRADE assessment. PubMed abstract Read 2026-10-23.
- J Nutr Health Aging 2022 Effectiveness of Partially Hydrolyzed Guar Gum in Reducing Constipation in Long Term Care Facility Residents: A Randomized Single-Blinded Placebo-Controlled Trial. PubMed abstract Read 2026-10-23.
- Nutrients 2019 Effect of Repeated Consumption of Partially Hydrolyzed Guar Gum on Fecal Characteristics and Gut Microbiota: A Randomized, Double-Blind, Placebo-Controlled, and Parallel-Group Clinical Trial. PubMed abstract Read 2026-10-23.
- Nutrition 2022 Acute intake of fructooligosaccharide and partially hydrolyzed guar gum on gastrointestinal transit: A randomized crossover clinical trial. PubMed abstract Read 2026-10-23.
- Eur J Nutr 2024 Effects of a prebiotic formulation on the composition of the faecal microbiota of people with functional constipation. PubMed abstract Read 2026-10-23.
- J Acad Nutr Diet 2017 Understanding the Physics of Functional Fibers in the Gastrointestinal Tract: An Evidence-Based Approach to Resolving Enduring Misconceptions about Insoluble and Soluble Fiber. PubMed abstract Read 2026-10-23.
- NHS (UK). Laxatives. Page last reviewed 30 April 2026. Read 2026-10-23.
- NHS (UK). Constipation. Page last reviewed 26 October 2023. Read 2026-10-23.
- International Scientific Association for Probiotics and Prebiotics (ISAPP). Prebiotics. 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.