Partially Hydrolyzed Guar Gum (PHGG) is a type of soluble dietary fiber used in nutritional supplements and clinical dietetics. This water-soluble powder is derived from the guar bean, the seed of the Cyamopsis tetragonoloba plant. PHGG is classified as a prebiotic, meaning it feeds beneficial gut bacteria rather than being digested by the body’s own enzymes. Its lack of viscosity distinguishes it from its parent compound, native guar gum, making it a versatile ingredient in various food and drink applications. This fiber promotes digestive health and regularity without the common drawbacks associated with other fiber supplements.
Chemical Structure and Source
The source material for PHGG is the guar bean, a legume cultivated primarily in India and Pakistan. Guar gum, the native substance extracted from the bean’s endosperm, is a galactomannan, a polysaccharide composed of a backbone of mannose sugars with side branches of galactose sugars. This structure gives native guar gum a high molecular weight and a strong tendency to form a thick, viscous gel when mixed with water.
The production of PHGG involves partial enzymatic hydrolysis. This technique uses enzymes to break the long polysaccharide chains of native guar gum into shorter fragments, dramatically reducing the molecular weight. This lower molecular weight prevents PHGG from forming a gel, resulting in a highly soluble product that remains a clear, thin liquid when dissolved. This low viscosity allows PHGG to be easily incorporated into beverages and liquid enteral nutrition formulas without altering their texture or palatability.
Digestive Function and Prebiotic Action
PHGG functions by resisting digestion in the upper gastrointestinal tract, passing through the stomach and small intestine largely intact. Since human digestive enzymes cannot break down the complex galactomannan structure, the fiber reaches the colon where it acts as a fermentable substrate. This non-digestible nature categorizes it as a prebiotic, providing nourishment for the colonic microbiota.
In the large intestine, PHGG is selectively fermented by beneficial bacteria, increasing the growth and activity of microbial populations like Bifidobacterium. This fermentation results in the production of Short-Chain Fatty Acids (SCFAs), which are potent metabolites. The most notable SCFA produced is butyrate, the preferred energy source for colonocytes, the cells lining the colon.
The consistent production of butyrate helps maintain the structural integrity and health of the colonic lining, reinforcing the gut barrier function. SCFAs also contribute to a lower pH in the colon, which discourages the proliferation of potentially harmful bacteria. By modulating the gut environment and selectively feeding beneficial microbes, PHGG helps restore microbial balance, supporting overall gastrointestinal wellness.
Primary Therapeutic Applications
PHGG is recognized for its “bowel normalizing” effect, making it a versatile intervention for various functional gastrointestinal disorders. For chronic constipation, PHGG increases stool bulk and accelerates colonic transit time, leading to more frequent and softer bowel movements. Clinical trials show that daily doses can significantly reduce the reliance on laxatives, especially in populations with long-term constipation.
For individuals with Irritable Bowel Syndrome (IBS), PHGG manages symptoms across both the constipation-dominant (IBS-C) and diarrhea-dominant (IBS-D) subtypes. Its ability to normalize stool consistency means it can absorb excess water in diarrhea while softening hard stools in constipation. Consistent supplementation has also been associated with a reduction in core IBS symptoms, including abdominal pain, discomfort, and bloating.
In hospital settings, PHGG is used to manage feeding intolerance, particularly for patients receiving enteral (tube) nutrition. Diarrhea is a common complication of tube feeding, and PHGG supplementation can significantly reduce its incidence and severity. Its low viscosity allows it to be easily mixed into liquid formulas without clogging feeding tubes, making it a practical option for clinical nutritional support.
Dosage, Mixing, and Gastrointestinal Tolerance
The typical effective daily dosage of PHGG for general digestive comfort and regularity starts at approximately 5 grams. For persistent issues like chronic constipation or irritable bowel syndrome, clinical studies often utilize doses ranging from 5 to 11 grams per day. It is recommended to begin with a lower dose, such as 3 grams, and gradually increase the amount over several weeks to allow the gut microbiota time to adapt.
PHGG offers superior user convenience due to its unique physical properties. Since the hydrolysis process eliminates the gelling characteristic of native guar gum, the powder is tasteless, odorless, and dissolves completely in most beverages without altering their texture. It can be mixed into hot or cold liquids, including water, coffee, juice, or soft foods like yogurt, without thickening.
The primary advantage of PHGG over many other fermentable fibers is its excellent gastrointestinal tolerance. Unlike faster-fermenting fibers that cause rapid gas production, PHGG undergoes slow and sustained fermentation throughout the colon. This slower metabolic rate results in a reduced incidence of common side effects like bloating, cramping, and flatulence. The risk of adverse gastrointestinal symptoms is notably lower with PHGG compared to high-viscosity fibers.