Partially Hydrolyzed Guar Gum (PHGG): The Clear, No-Gel Fiber, Explained

Partially hydrolyzed guar gum (PHGG) is a soluble fiber made by using an enzyme to cut the long chains of guar gum into much shorter pieces, so it dissolves clear in water instead of turning thick. It passes through the small intestine undigested and is fermented by bacteria in the large intestine, which is why researchers study it as a prebiotic fiber.

Here is how it is made, what studies in healthy adults measured, and how to start.

Key takeaways

• PHGG comes from guar beans. Enzymatic processing shortens the guar chains to less than one-tenth of their original length, which is why it stays thin and clear in water.
• It is a soluble, fermentable fiber. Gut bacteria break it down into short-chain fatty acids such as acetate, propionate and butyrate.
• Studies in healthy adults have used from 3 g to about 21 g per day, with several using 3 g to 6 g, and measured stool frequency, stool form and gut bacteria.
• More than 90 percent of American women and 97 percent of men fall short of recommended fiber intakes, according to the Dietary Guidelines for Americans.
• Start low, add water, and increase slowly. Food comes first; a fiber supplement fills gaps.

What PHGG is and why it does not gel

Guar gum is a carbohydrate from the seed of the guar plant (Cyamopsis tetragonolobus). It is built from a long backbone of the sugar mannose with galactose side branches, a structure called a galactomannan. In its intact form, guar gum is a thickener: a 1% solution has a viscosity of roughly 2,000 to 3,000 mPa·s.

To make PHGG, manufacturers treat guar gum with a mannanase enzyme that snips the backbone at intervals. The chemical building blocks stay the same, but the chains end up less than one-tenth of their original length. As a result, a 5% PHGG solution has a viscosity of only about 10 mPa·s, close to water. The result is a fiber that dissolves clear in drinks without changing their taste or texture, and that holds up to heat and acidity.

Many familiar soluble fibers behave differently. MedlinePlus describes soluble fiber as attracting water and forming a gel during digestion. PHGG is soluble but low in viscosity, so it mixes without grit or sludge.

Soluble vs. insoluble fiber, and where fermentation fits

When fermentable fiber reaches the colon, bacteria break it down and produce short-chain fatty acids (SCFAs). In a laboratory study that fermented PHGG with stool samples from six healthy donors, the average SCFA mix was about 30:45:25 acetate to propionate to butyrate. The total amount produced varied more than twofold from person to person, a reminder that everyone's gut bacteria are different.

The International Scientific Association for Probiotics and Prebiotics defines a prebiotic as a substrate that is selectively used by host microorganisms and confers a health benefit. PHGG is researched against that definition: does it shift specific bacteria, and do those shifts come with a measurable benefit?

What human studies in healthy adults measured

The research below was done on PHGG as an ingredient, not on any finished MAXIS product. Some trials were funded or co-authored by the company that makes the branded ingredient, which is common in this field and worth keeping in mind.

• Bowel habits, 8 weeks. In a randomized, double-blind, placebo-controlled trial in healthy men and women, participants took 3 g or 5 g of PHGG per day. Bowel movement frequency and participants' ratings of how bowel movements felt improved in the fiber groups, and the difference reached statistical significance at 5 g compared with placebo (Abe et al., 2023).
• Stool form, 12 weeks. In 44 healthy adults whose stools tended toward the soft end of the Bristol Stool Scale, 5 g per day moved stool form toward the middle of the scale compared with baseline. Stool frequency did not differ from placebo. Bifidobacteria increased in the PHGG group (Yasukawa et al., 2019).
• Stool frequency and butyrate, 3 weeks. In 20 healthy volunteers taking 5 g up to three times a day, PHGG significantly affected stool frequency and consistency, and stool levels of butyrate and acetate rose. Most changes faded after people stopped taking it (Reider et al., 2020).
• Gut bacteria at low doses, 14 days. In 33 healthy adults who normally ate 14 g of fiber a day or less, 3 g and 6 g per day both shifted several bacterial groups compared with placebo (Edelman et al., 2024).
• An early study, 14 days. Nine healthy volunteers took 7 g three times a day. Bifidobacteria counts rose and stool pH fell during intake, and bacterial counts drifted back toward baseline within two weeks of stopping (Okubo et al., 1994).

Two patterns stand out. First, several of the trials used modest amounts, 3 g to 6 g a day. Second, the effects seem to depend on continued intake; when people stopped, their gut bacteria drifted back.

How much fiber Americans eat, and how much is recommended

The Dietary Guidelines for Americans, 2020–2025, set fiber goals at 14 g per 1,000 calories, based on the Dietary Reference Intakes. For adults, that works out to roughly 22 g to 34 g per day depending on age and sex. The newer 2025–2030 edition, released in January 2026, continues to encourage fiber-rich foods.

Actual intake falls well short. National survey data from 2001 to 2010 put average adult intake at about 16 g per day, and the Dietary Guidelines report that more than 90 percent of women and 97 percent of men do not meet their fiber goal. The most reliable way to close the gap is more vegetables, fruit, beans and whole grains. A clear fiber is a convenient way to add a few grams on top of that.

How to start

• Start low. Begin with a single serving a day and stay there for a week or so before adding more. MedlinePlus advises increasing fiber slowly, and notes that gas or bloating is a sign to cut back for a few days.
• Drink enough fluid. When you add fiber, you also need enough water. Mix PHGG into a full glass and keep up your usual fluid intake.
• Be consistent. The studies above gave PHGG daily for weeks, and the measured changes faded when intake stopped.
• Pick a time that is easy to remember. Because it dissolves clear, PHGG can go into water, coffee, tea or a smoothie.

Check with a clinician first if you are pregnant or nursing, take prescription medications, have a diagnosed digestive condition, or have had digestive surgery. See a doctor promptly for new or persistent changes in bowel habits, ongoing abdominal pain, or blood in the stool rather than trying to manage them with a supplement.

Where MAXIS Soluble Clear Fiber fits

MAXIS Soluble Clear Fiber has one ingredient: SunFiber® partially hydrolyzed guar gum from Taiyo. Each tablespoon (about 4 g) provides 3 g of soluble fiber and 20 calories, and it dissolves clear with no grit and no gel. The container holds 142 g, about 35 servings.

One tablespoon sits at the lower end of the amounts used in the studies above. As a prebiotic soluble fiber, it supports digestion and normal bowel regularity.† Follow the label directions, and build up gradually.

FAQ

Is PHGG the same as guar gum?

It comes from guar gum and has the same building blocks, but the chains are much shorter. That is why guar gum thickens liquids and PHGG does not.

Will PHGG cause gas?

Any fermentable fiber can cause some gas, especially when you add a lot at once. Starting with a small amount and increasing slowly gives your gut bacteria time to adjust.

Does a fiber supplement replace high-fiber foods?

No. Whole foods bring fiber along with many other nutrients. Use a supplement to help close the gap, not to replace vegetables, fruit, beans and whole grains.

References

1. Yoon SJ, Chu DC, Juneja LR (2008). Chemical and physical properties, safety and application of partially hydrolized guar gum as dietary fiber. Journal of Clinical Biochemistry and Nutrition. PubMed
2. Gibson GR, Hutkins R, Sanders ME, et al. (2017). Expert consensus document: The International Scientific Association for Probiotics and Prebiotics (ISAPP) consensus statement on the definition and scope of prebiotics. Nature Reviews Gastroenterology & Hepatology. PubMed
3. Carlson J, Esparza J, Swan J, Taussig D, Combs J, Slavin J (2016). In vitro analysis of partially hydrolyzed guar gum fermentation differences between six individuals. Food & Function. PubMed
4. Abe A, Morishima S, Kapoor MP, et al. (2023). Partially hydrolyzed guar gum is associated with improvement in gut health, sleep, and motivation among healthy subjects. Journal of Clinical Biochemistry and Nutrition. PubMed
5. Yasukawa Z, Inoue R, Ozeki M, et al. (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. Nutrients. PubMed
6. Reider SJ, Moosmang S, Tragust J, et al. (2020). Prebiotic effects of partially hydrolyzed guar gum on the composition and function of the human microbiota: results from the PAGODA trial. Nutrients. PubMed
7. Edelman M, Wang Q, Ahnen R, Slavin J (2024). The dose response effects of partially hydrolyzed guar gum on gut microbiome of healthy adults. Applied Microbiology. DOI
8. Okubo T, Ishihara N, Takahashi H, et al. (1994). Effects of partially hydrolyzed guar gum intake on human intestinal microflora and its metabolism. Bioscience, Biotechnology, and Biochemistry. DOI
9. Oklahoma State University Extension (2026). The New Dietary Guidelines for Americans, 2025–2030. OSU Extension
10. U.S. Department of Agriculture and U.S. Department of Health and Human Services (2020). Dietary Guidelines for Americans, 2020–2025. DietaryGuidelines.gov
11. McGill CR, Fulgoni VL, Devareddy L (2015). Ten-year trends in fiber and whole grain intakes and food sources for the United States population: NHANES 2001–2010. Nutrients. PubMed
12. MedlinePlus (U.S. National Library of Medicine). Soluble vs. insoluble fiber; and Fiber. MedlinePlus; MedlinePlus

†These statements have not been evaluated by the Food and Drug Administration. This product is not intended to diagnose, treat, cure, or prevent any disease.