Is PHGG Soluble or Insoluble Fiber? The Definitive Guide

December 9, 2025 •

4 min read

According to the National Institutes of Health, partially hydrolyzed guar gum (PHGG) is a water-soluble dietary fiber. While its parent compound, guar gum, is highly viscous and gelling, PHGG undergoes an enzymatic process that breaks it down into a form that dissolves easily and remains liquid when mixed with fluids. This unique processing gives PHGG distinct advantages as a well-tolerated prebiotic fiber for gut health.

Quick Summary

PHGG is a water-soluble fiber derived from guar beans through enzymatic hydrolysis. This process significantly reduces its viscosity, creating a low-gelling, easy-to-mix fiber that provides numerous gut health benefits without the gas and bloating common with other fibers. It acts as a prebiotic, normalizing bowel movements and supporting healthy gut flora.

Key Points

PHGG is Soluble: Partially Hydrolyzed Guar Gum (PHGG) is definitively a water-soluble fiber, not an insoluble one.
Low Viscosity: Unlike traditional guar gum, PHGG is enzymatically processed to create a low-viscosity fiber that dissolves completely in water and does not form a thick gel.
Prebiotic Benefits: PHGG acts as a prebiotic, fermenting slowly in the large intestine to feed beneficial bacteria like Bifidobacterium and produce health-supporting short-chain fatty acids.
Gentle on Digestion: Due to its slow fermentation and low gelling properties, PHGG causes less gas and bloating compared to other soluble fibers, making it well-tolerated by those with sensitive stomachs or IBS.
Regulates Bowel Function: PHGG is a versatile fiber that can help normalize bowel movements, addressing both constipation by increasing stool frequency and diarrhea by improving stool consistency.
Supports Overall Health: Beyond digestive balance, PHGG has been clinically studied for its potential benefits in blood sugar control, cholesterol management, and satiety.
Versatile Supplement: As a tasteless, odorless powder, PHGG can be easily added to a wide variety of foods and beverages without altering their flavor or texture.

What is Partially Hydrolyzed Guar Gum (PHGG)?

Partially Hydrolyzed Guar Gum, or PHGG, is a versatile dietary fiber made from the guar bean (Cyamopsis tetragonolobus). Its raw form, guar gum, is known for its high viscosity and is used as a thickening and stabilizing agent in the food industry. However, to create PHGG, manufacturers use a controlled enzymatic hydrolysis process to break down the long polysaccharide chains of the guar gum. The result is a much shorter, lower molecular weight fiber that retains the benefits of guar gum but with a drastically reduced viscosity. This low-viscosity property is what allows PHGG to dissolve completely in water without gelling, making it a tasteless, odorless, and highly palatable fiber supplement.

The Key Differences Between PHGG and Guar Gum

Understanding the distinction between PHGG and its parent compound, guar gum, is critical to understanding its functionality. While both are sourced from the guar bean, their physical properties and uses differ significantly due to the hydrolysis process. Guar gum's high viscosity can cause esophageal or intestinal blockages if consumed in large quantities, leading the FDA to implement strict guidelines on its use. Conversely, PHGG's low viscosity makes it a safe and well-tolerated fiber supplement suitable for a wide range of applications, from beverages to clinical nutrition.

Why PHGG is Classified as a Soluble Fiber

PHGG is definitively a soluble fiber, as it dissolves completely in water. This is a defining characteristic of all soluble fibers, which form a gel-like substance in the digestive tract that slows digestion. However, PHGG is unique among soluble fibers for its low viscosity and high fermentability. Unlike many other soluble fibers that form thick gels and can cause significant gas and bloating, PHGG is slowly fermented by the gut bacteria. This slow fermentation reduces the build-up of gas, making it a gentler and more comfortable option for individuals with sensitive digestive systems, including those with Irritable Bowel Syndrome (IBS).

The Function of Soluble Fiber in the Gut

Soluble fiber, like PHGG, is not digested in the upper gastrointestinal tract but is fermented by the beneficial microbes in the large intestine. This fermentation produces short-chain fatty acids (SCFAs), such as butyrate, acetate, and propionate, which serve as a primary energy source for colon cells. These SCFAs are crucial for maintaining the health of the gut lining and supporting a balanced gut microbiome. The prebiotic effect of PHGG, which promotes the growth of beneficial bacteria like Bifidobacterium, contributes to overall gut health and has been linked to improvements in bowel regularity, stool consistency, and symptoms of IBS.

Comparison Table: PHGG vs. Other Common Fibers


Feature	PHGG (Partially Hydrolyzed Guar Gum)	Psyllium Husk (Soluble)	Wheat Bran (Insoluble)
Fiber Type	Soluble, highly soluble	Soluble, forms a thick gel	Insoluble, non-gelling
Viscosity	Very low	Very high	N/A
Fermentability	High, slow fermentation	High, rapid fermentation	Low
Gastrointestinal Impact	Well-tolerated, less gas/bloating	Can cause significant gas/bloating	Adds bulk, speeds transit time
Mixing	Dissolves clearly and easily	Forms a thick, gelatinous mixture	Does not dissolve
Primary Function	Prebiotic, regulates bowel function, feeds beneficial bacteria	Bulking agent, promotes regularity	Bulking agent, aids laxation

The Health Benefits of PHGG

PHGG's classification as a soluble, prebiotic fiber with low viscosity gives it a unique set of health benefits. Research and clinical studies have validated its effectiveness in addressing a range of digestive issues and promoting overall wellness.

Relieves Constipation: By absorbing water, PHGG can improve stool consistency and increase bowel movement frequency, helping to normalize transit time in constipated individuals.
Manages Diarrhea: In cases of loose stools or diarrhea, PHGG can help normalize bowel movements by binding to excess water. Its ability to regulate transit time means it can both accelerate and slow it down as needed to promote balance.
Supports IBS Symptoms: Studies have shown that PHGG can significantly improve symptoms associated with Irritable Bowel Syndrome, including abdominal pain, bloating, and gas. Its gentle fermentation makes it a preferred option over other fibers that may exacerbate these issues.
Acts as a Prebiotic: PHGG nourishes and promotes the growth of beneficial gut bacteria, particularly Bifidobacterium and Lactobacillus. This helps to restore a healthy balance to the gut microbiome.
Supports Blood Sugar and Cholesterol: Soluble fibers can help slow the absorption of sugars and fats. PHGG has been shown to reduce post-meal blood sugar spikes and may help lower serum cholesterol levels.
Enhances Satiety: Because soluble fiber helps to slow digestion, PHGG can contribute to a feeling of fullness, which may assist with weight management.

Conclusion

In summary, PHGG is a soluble fiber, but its specific processing gives it advantageous characteristics that set it apart from other fibers in its class. Unlike its highly viscous precursor, guar gum, PHGG dissolves easily in water, is tasteless, and does not form a thick gel. This makes it a highly palatable and gentle fiber supplement that effectively addresses a spectrum of digestive issues, including constipation and diarrhea, and provides significant prebiotic benefits to support a healthy gut microbiome. Its slow fermentation process minimizes the gas and bloating that can often accompany fiber supplementation, cementing its status as a well-tolerated and effective choice for digestive health. For those seeking to improve their gut health and regularity, PHGG offers a reliable and comfortable solution.

The Importance of Variety in Fiber Intake

While PHGG offers numerous benefits as a soluble fiber, a balanced diet is most effective for long-term digestive health. Combining different sources of both soluble and insoluble fibers—from fruits, vegetables, whole grains, and legumes—is essential. PHGG can serve as an excellent, versatile supplement to bridge any gaps in dietary fiber intake, ensuring you receive a broad range of benefits for your gut and overall well-being.

Frequently Asked Questions

PHGG is slowly fermented by gut bacteria, which reduces the rapid gas production that often occurs with other types of soluble fibers. As a result, it is generally very well-tolerated and associated with significantly less gas and bloating.

While both come from the guar bean, PHGG is created by enzymatically breaking down guar gum's long chains into shorter ones. This process drastically lowers its viscosity, preventing it from forming a thick gel like regular guar gum and making it easy to mix into liquids.

Yes, PHGG is a regulating fiber that can normalize bowel movements. It helps with constipation by drawing water into the colon to soften stool, and with diarrhea by absorbing excess water to improve stool consistency.

Yes, PHGG is a well-established prebiotic fiber. It selectively nourishes and promotes the growth of beneficial gut bacteria, such as Bifidobacterium and Lactobacillus.

PHGG is typically sold as a tasteless, odorless powder that dissolves clearly in water or other beverages. It can be easily mixed into drinks, smoothies, yogurt, or other foods without affecting their taste or texture.

Clinical studies have shown that PHGG can be effective in managing irritable bowel syndrome (IBS) symptoms, including bloating and abdominal pain. Its superior tolerability compared to other fibers makes it a preferred option for many with IBS.

PHGG has a long history of safe use and is generally recognized as safe (GRAS) by regulatory bodies. Numerous human clinical trials support its safety and efficacy for both short-term and long-term use.