Moderate evidenceGut health

Partially Hydrolyzed Guar Gum

A low-viscosity soluble fiber that is unusually well tolerated for a fermentable fiber. Small randomized trials support modest benefits in IBS and constipation.

Evidence last reviewed: August 2026

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What the science says

IBS symptoms Moderate evidence
A randomized, placebo-controlled trial in IBS patients found improvement in symptom scores with PHGG, and older randomized comparisons found it at least as good as wheat bran with fewer complaints. Trials are small and mostly single-center.
Constipation and stool form Moderate evidence
A randomized placebo-controlled trial in long-term care residents reduced constipation, and a randomized, double-blind trial in healthy adults improved fecal characteristics and shifted the gut microbiota.
Tolerability compared with other fibers Limited evidence
Trials consistently report low rates of gas and bloating relative to inulin or FOS, but this comes from adverse-event reporting rather than from head-to-head tolerability studies.

Dosage & safety

Studied doseTrials used roughly 5–7 g per day (some up to 11 g), stirred into liquid. It dissolves without thickening, which is why it is used in drinks and tube feeds.

SafetyUsually well tolerated; mild gas early on. Like all soluble fibers, take it separated by a couple of hours from medications to avoid interfering with absorption, and with adequate fluid.

Scientific references

Randomized clinical study: Partially hydrolyzed guar gum (PHGG) versus placebo in the treatment of patients with irritable bowel syndrome
Niv E, Halak A, Tiommny E, Yanai H, Strul H, Naftali T, Vaisman N — Nutr Metab (Lond), 2016
Effectiveness of Partially Hydrolyzed Guar Gum in Reducing Constipation in Long Term Care Facility Residents: A Randomized Single-Blinded Placebo-Controlled Trial
Chan TC, Yu VMW, Luk JKH, Chu LW, Yuen JKY, Chan FHW — J Nutr Health Aging, 2022
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
Yasukawa Z, Inoue R, Ozeki M, Okubo T, Takagi T, Honda A, Naito Y — Nutrients, 2019

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