Home Ingredients Sunfiber® (Partially Hydrolyzed Guar Gum)
Gut Health

Sunfiber® (Partially Hydrolyzed Guar Gum)

Evidence Level
Very Strong
5 Clinical Trials
6 Documented Benefits
5/5 Evidence Score

Sunfiber® is the original and most extensively clinically-studied partially hydrolyzed guar gum (PHGG) — manufactured by Taiyo International (Japan, founded 1946). Same core ingredient as Fibalance® but with more extensive clinical research history, established Low FODMAP and Monash certification, regulatory approvals globally (US GRAS, EU Novel Food, Japan FOSHU), and used in major medical nutrition products. Used in pediatric, geriatric, IBS, hospital nutrition, and consumer fiber products worldwide.

Studied Dose 5-7 g/day for digestive applications; up to 21 g/day in some clinical trials; pediatric formulations 3-5 g/day
Active Compound Partially hydrolyzed guar gum (PHGG)

Benefits

IBS Symptom Management (Strongest Evidence Among PHGG)

Multiple Sunfiber RCTs in IBS — Parisi 2002, Russo 2015, others — showed significant IBS symptom improvements. Component of evidence-based IBS dietary guidelines. More extensive clinical trial history than other PHGG forms.

Supported by Trial 1, Trial 2

Pediatric Constipation

Sunfiber widely used in pediatric formulations for constipation. Polymeric Plus® (medical nutrition) and others use Sunfiber. Pediatric-friendly tolerability.

Supported by Trial 3

Hospital / Medical Nutrition

Used in enteral nutrition formulas to support gut function in critically-ill, post-operative, and tube-fed patients. Maintains microbiome and reduces complications.

Supported by Trial 5

Glycemic Management

PHGG slows gastric emptying and modestly attenuates postprandial glucose. Some Sunfiber trials show glycemic improvements in T2D patients.

Supported by Trial 3, Trial 4

Cholesterol Reduction (Modest)

Soluble fiber generally reduces cholesterol; PHGG provides modest cholesterol-lowering effects (~5-10% LDL reduction in some trials).

Supported by Trial 1, Trial 2

Microbiome Diversity Support

Fermentation supports diverse beneficial bacteria; gentler than FOS/inulin. Useful for restoring microbiome after antibiotics or dysbiosis.

Supported by Trial 2

Mechanism of action

1

Same as Fibalance — PHGG Mechanism

Slow colonic fermentation; SCFA production; bifidogenic; Lactobacillus-supportive; stool normalization. See Fibalance entry for mechanism details.

2

Established Manufacturing Standardization

Taiyo's manufacturing process produces consistent PHGG with documented molecular weight distribution, water solubility, low viscosity. Decades of process refinement.

3

Low Viscosity Despite High Fiber Content

PHGG's partial hydrolysis from native guar gum reduces viscosity dramatically — Sunfiber is essentially clear and tasteless in water at typical use levels. Key for product applications.

4

85%+ Soluble Dietary Fiber

High soluble fiber content ensures full prebiotic and fermentation effects. Higher fiber per gram than many alternative fibers.

Clinical trials

1
Parisi 2002: PHGG vs Wheat Bran for IBS

Multicenter, randomized, open-label trial comparing PHGG 5 g/day to wheat bran 30 g/day for 12 weeks, measuring abdominal pain, bowel habits, and overall subjective rating.

188 adult IBS patients (139 women, 49 men) across multiple Italian gastroenterology centers.

Both fibers improved symptoms, but PHGG produced significantly greater success (60% vs 40%, ITT) and far better tolerability. Patients crossing from wheat bran to PHGG at week 4 (49.9%) vastly outnumbered the reverse (10.9%), supporting PHGG as a more acceptable IBS fiber.

2
Niv 2016: Placebo-Controlled PHGG for IBS Bloating

Double-blind placebo-controlled RCT spanning 18 weeks (2-wk run-in, 12-wk treatment, 4-wk follow-up) of PHGG 6 g/day vs placebo, with daily symptom journals.

121 IBS patients randomized (108 completed: 49 PHGG, 59 placebo) at multiple Israeli centers.

PHGG showed significant improvement in journal bloating scores and combined bloating-and-gas symptoms vs placebo, with benefits persisting 4 weeks after stopping the fiber. The PHGG group also had lower dropout, supporting tolerability. Broader IBS quality-of-life measures did not differ significantly.

3
Ustundag 2010: PHGG vs Lactulose in Children

Randomized controlled trial comparing PHGG to lactulose over 4 weeks in pediatric functional constipation, measuring weekly defecation frequency, stool consistency, and family-reported tolerability.

61 children with chronic functional constipation at a Turkish pediatric gastroenterology clinic.

PHGG produced bowel-frequency and stool-consistency improvements equivalent to lactulose (the standard osmotic laxative), but with markedly better palatability. Parents reported lactulose caused bad taste and flatulence, while families using PHGG expressed greater satisfaction overall.

4
Yasukawa 2019: Sunfiber Bifidobacterium Trial

Randomized, double-blind, placebo-controlled, parallel-group trial of Sunfiber PHGG 5 g/day vs placebo for 12 weeks plus 4-week washout, with stool diaries and 16S microbiota sequencing.

44 healthy Japanese adults (mean age 41.9) with loose-stool tendencies, 22 per group.

PHGG normalized Bristol Stool Scale scores toward 4.0 and significantly increased Bifidobacterium abundance while decreasing Bacteroides relative to placebo. Stool frequency was unchanged, supporting a stool-quality and prebiotic effect rather than a laxative effect.

5
Spapen 2001: PHGG-Enriched Tube Feeding in Sepsis

Prospective, double-blind, randomized controlled trial comparing enteral formula with 22 g/L PHGG vs isocaloric/isonitrogenous fiber-free formula for at least 6 days via nasogastric tube.

25 ICU patients with severe sepsis or septic shock (13 PHGG, 12 control) at a Belgian academic hospital.

Mean percentage of days with diarrhea was 8.8% in the PHGG group vs 32.0% in the fiber-free control group (p=0.001), supporting use of PHGG to help maintain bowel function in critically ill tube-fed patients. No effect on sepsis mortality or ICU length of stay.

Side effects and drug interactions

Common Potential side effects

Excellent GI tolerability (same as Fibalance/PHGG generally).
Mild initial bloating possible.
Allergic reactions to legumes possible.
Esophageal obstruction risk if taken without adequate water.

Important Drug interactions

Same as Fibalance/PHGG generally.
Fiber may delay medication absorption — separate by 1-2 hours.
Diabetes medications — modest hypoglycemic potentiation.
Lipid medications — modest additive cholesterol effects.
Pregnancy/lactation — well-established safety; widely used.
Pediatric — Sunfiber is among the safest fibers for children.

Featured in these supplement guides

Bloating→Blood Sugar Control→Constipation→IBS→Weight Loss→

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Frequently asked questions about Sunfiber® (Partially Hydrolyzed Guar Gum)

What is Sunfiber?

Sunfiber® is the original and most extensively clinically-studied partially hydrolyzed guar gum (PHGG) — manufactured by Taiyo International (Japan, founded 1946).

What is Sunfiber used for?

Sunfiber is researched primarily for Gut Health. Multiple Sunfiber RCTs in IBS — Parisi 2002, Russo 2015, others — showed significant IBS symptom improvements. Component of evidence-based IBS dietary guidelines. More extensive clinical trial history than other PHGG forms.

What is the recommended dosage of Sunfiber?

The clinically studied dose is 5-7 g/day for digestive applications; up to 21 g/day in some clinical trials; pediatric formulations 3-5 g/day Always follow the product label and check with a healthcare provider for personal advice.

Is Sunfiber safe, and does it have side effects?

For most healthy adults, Sunfiber is well tolerated at studied doses. Reported effects can include: Excellent GI tolerability (same as Fibalance/PHGG generally). Mild initial bloating possible. It may also interact with some medications. Sunfiber is not right for everyone, so check with a healthcare provider first if you are pregnant or breastfeeding, have a medical condition, or take prescription medication.

Does Sunfiber interact with any medications?

Possible interactions include: Same as Fibalance/PHGG generally. Fiber may delay medication absorption — separate by 1-2 hours. If you take prescription medication, check with a pharmacist or doctor before using it.

How strong is the scientific evidence for Sunfiber?

NutraSmarts rates the evidence for Sunfiber as Very Strong (5 out of 5). It is backed by 5 clinical trials and 8 cited references summarized on this page. A higher rating reflects more, larger, and better-designed human studies.

References(8 citations)

Evidence ratings on NutraSmarts are based on the totality of human clinical research, with emphasis on randomized controlled trials, meta-analyses, and systematic reviews. The references below directly support claims made throughout this page.

  1. Parisi GC, Zilli M, Miani MP, Carrara M, Bottona E, Verdianelli G, Battaglia G, Desideri S, Faedo A, Marzolino C, Tonon A, Ermani M, Leandro G. High-fiber diet supplementation in patients with irritable bowel syndrome (IBS): a multicenter, randomized, open trial comparison between wheat bran diet and partially hydrolyzed guar gum (PHGG). Dig Dis Sci. 2002;47(8):1697-704. doi: 10.1023/a:1016419906546.PubMedUsed to support: IBS symptom improvement: PHGG 5 g/day produced significantly greater overall success (60%) than wheat bran 30 g/day (40%) over 12 weeks in 188 adult IBS patients, with superior tolerability.
  2. Niv E, Halak A, Tiommny E, Yanai H, Strul H, Naftali T, Vaisman N. Randomized clinical study: Partially hydrolyzed guar gum (PHGG) versus placebo in the treatment of patients with irritable bowel syndrome. Nutr Metab (Lond). 2016;13:10. doi: 10.1186/s12986-016-0070-5.PubMedUsed to support: IBS bloating/gas improvement: 12-week double-blind placebo-controlled trial of PHGG 6 g/day in IBS patients showed significant improvement in bloating and gas scores; benefit persisted 4 weeks post-treatment.
  3. Russo L, Andreozzi P, Zito FP, Vozzella L, Savino IG, Sarnelli G, Cuomo R. Partially hydrolyzed guar gum in the treatment of irritable bowel syndrome with constipation: effects of gender, age, and body mass index. Saudi J Gastroenterol. 2015;21(2):104-10. doi: 10.4103/1319-3767.153835.PubMedUsed to support: IBS-C symptom improvement: PHGG significantly improved symptom scores, laxative/enema use, stool form, and colonic transit time in IBS-C patients, with effect sizes varying by gender, age, and BMI.
  4. Üstündağ G, Kuloğlu Z, Kirbaş N, Kansu A. Can partially hydrolyzed guar gum be an alternative to lactulose in treatment of childhood constipation? Turk J Gastroenterol. 2010;21(4):360-4. doi: 10.4318/tjg.2010.0121.PubMedUsed to support: Pediatric constipation: 4-week RCT in 61 children showed PHGG produced bowel-frequency and stool-consistency improvements equivalent to lactulose, with better palatability and parental satisfaction.
  5. Spapen H, Diltoer M, Van Malderen C, Opdenacker G, Suys E, Huyghens L. Soluble fiber reduces the incidence of diarrhea in septic patients receiving total enteral nutrition: a prospective, double-blind, randomized, and controlled trial. Clin Nutr. 2001;20(4):301-5. doi: 10.1054/clnu.2001.0399.PubMedUsed to support: Hospital/enteral nutrition: PHGG-supplemented enteral formula (22 g/L) reduced diarrhea days from 32% to 8.8% in septic ICU patients on tube feeding (p=0.001).
  6. Dall'Alba V, Silva FM, Antonio JP, Steemburgo T, Royer CP, Almeida JC, Gross JL, Azevedo MJ. Improvement of the metabolic syndrome profile by soluble fibre - guar gum - in patients with type 2 diabetes: a randomised clinical trial. Br J Nutr. 2013;110(9):1601-10. doi: 10.1017/S0007114513001025.PubMedUsed to support: Glycemic management: 6-week RCT in 44 T2D adults with metabolic syndrome found PHGG 10 g/day reduced HbA1c, waist circumference, and urinary albumin vs control.
  7. Yasukawa Z, Inoue R, Ozeki M, Okubo T, Takagi T, Honda A, Naito Y. 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. Nutrients. 2019;11(9):2170. doi: 10.3390/nu11092170.PubMedUsed to support: Microbiome / Bifidobacterium prebiotic effect: 12-week RCT in 44 healthy Japanese adults found Sunfiber PHGG 5 g/day normalized Bristol stool scores and increased Bifidobacterium abundance vs placebo.
  8. Reider SJ, Moosmang S, Tragust J, Trgovec-Greif L, Tragust S, Perschy L, Przysiecki N, Sturm S, Tilg H, Stuppner H, Rattei T, Moschen AR. Prebiotic Effects of Partially Hydrolyzed Guar Gum on the Composition and Function of the Human Microbiota-Results from the PAGODA Trial. Nutrients. 2020;12(5):1257. doi: 10.3390/nu12051257.PubMedUsed to support: Microbiome diversity / SCFA production: 9-week PAGODA trial in 20 healthy adults showed escalating-dose PHGG (5-15 g/day) increased Faecalibacterium and Ruminococcus and raised fecal butyrate and acetate.