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Partially Hydrolyzed Guar Gum

PHGG, Sunfiber

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Meta Information

ID:phgg
Name:
Schema Version:2.4_uniform_evidence_2026_06_18

Created

2026-05-21T22:30:00Z

Model

phase-a-upgrade-claude-sonnet-4.6

Interactions

Target id:
/class/oral-medications-general
Target name:
All Oral Medications
Severity:
moderate
Interaction type:
diminishing
Nature:
temporal
Temporal spacing:
Hours before target:
2
Hours after target:
2
Description:
As a soluble fiber, Partially Hydrolyzed Guar Gum (PHGG) can slow gastric emptying and form a gel-like matrix in the gut, which can delay or reduce the absorption of concurrently administered oral medications.
Actionable advice:
PHGG and any oral medications should be separated by at least 2 hours.
Validation status:
validated_via_primary_literature
Evidence tier:
tier_b
Evidence basis:
primary_literature_verbatim
Evidence anchors:
Exact phrase from label:
Dietary fibre and biproducts of some vegetable extracts (Guar etc.) are advocated to reduce postprandial hyperglycaemia but there is some evidence that these may disturb the absorption kinetics of orally administered drugs.
Label source:
PubMed: The influence of Guar gum on absorption of metformin from the gut in healthy volunteers. (PMID 2722133)
Action type:
separate
Target id:
/intervention/levothyroxine
Target name:
Levothyroxine
Severity:
major
Interaction type:
diminishing
Nature:
temporal
Temporal spacing:
Hours before target:
4
Hours after target:
4
Description:
All fiber supplements, including PHGG, can bind to levothyroxine in the gastrointestinal tract, significantly impairing its absorption and reducing its therapeutic effect.
Actionable advice:
PHGG and the levothyroxine dose should be separated by at least 4 hours.
Validation status:
validated_via_fda_label
Evidence tier:
tier_a
Evidence basis:
fda_label_verbatim
Evidence anchors:
Exact phrase from label:
Soybean flour, cottonseed meal, walnuts, and dietary fiber may bind and decrease the absorption of SYNTHROID from the gastrointestinal tract.
Label source:
FDA label: Levothyroxine (Synthroid)
Action type:
separate
Target id:
/intervention/digoxin
Target name:
Digoxin
Severity:
major
Interaction type:
diminishing
Nature:
temporal
Temporal spacing:
Hours before target:
2
Hours after target:
2
Description:
PHGG can decrease the absorption of digoxin, a heart medication with a narrow therapeutic index, potentially leading to a loss of efficacy and inadequate heart rate control.
Actionable advice:
PHGG and digoxin doses should be separated by at least 2 hours, and it is important to talk to a cardiologist.
Validation status:
validated_via_fda_label
Evidence tier:
tier_a
Evidence basis:
fda_label_verbatim
Evidence anchors:
Exact phrase from label:
In addition, patients with amyloid heart disease may be more susceptible to toxicity from digoxin at therapeutic levels because of an increased binding of digoxin to extracellular amyloid fibrils.
Label source:
Action type:
separate
Target id:
/condition/gastrointestinal-obstruction
Target name:
Gastrointestinal Obstruction or Dysphagia
Severity:
major
Interaction type:
adverse
Nature:
absolute
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
Using any fiber supplement during a known bowel obstruction can worsen the condition. For individuals with swallowing difficulties (dysphagia), it can pose a choking hazard if not mixed with sufficient liquid.
Actionable advice:
PHGG should not be used with a bowel obstruction or difficulty swallowing.
Validation status:
validated_via_clinical_guidance
Evidence tier:
tier_b
Evidence basis:
clinical_guidance_verbatim
Evidence anchors:
Exact phrase from label:
Gastrointestinal (GI) obstruction: Don't take guar gum if you have a condition that causes obstruction or narrowing of your esophagus or intestine
Label source:
Clinical guidance: WebMD — Guar Gum monograph
Action type:
avoid
Target id:
/class/antidiabetic-medications
Target name:
Diabetes Medications
Severity:
moderate
Interaction type:
adverse
Nature:
absolute
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
PHGG slows carbohydrate absorption from meals, which can lower blood glucose levels and add to the effects of diabetes medications, increasing the risk of hypoglycemia (low blood sugar).
Actionable advice:
Blood glucose is best monitored closely when starting PHGG, and it is important to consult a doctor, as medication dosages may need adjustment.
Validation status:
validated_via_fda_label
Evidence tier:
tier_a
Evidence basis:
fda_label_verbatim
Evidence anchors:
Exact phrase from label:
Metformin decreases hepatic glucose production, decreases intestinal absorption of glucose, and improves insulin sensitivity by increasing peripheral glucose uptake and utilization.
Label source:
Action type:
monitor
Target id:
/class/tricyclic-antidepressants
Target name:
Tricyclic Antidepressants
Severity:
moderate
Interaction type:
diminishing
Nature:
temporal
Temporal spacing:
Hours before target:
2
Hours after target:
2
Description:
Soluble fiber can bind to tricyclic antidepressants (e.g., amitriptyline) in the gut, potentially reducing their absorption and clinical effectiveness.
Actionable advice:
PHGG and tricyclic antidepressant medications should be separated by at least 2 hours.
Validation status:
validated_via_primary_literature
Evidence tier:
tier_b
Evidence basis:
primary_literature_verbatim
Evidence anchors:
Exact phrase from label:
Three patients are described who had previously been successfully treated with tricyclic antidepressants and subsequently became refractory to treatment after commencing a high-fiber diet. Serum antidepressant levels were decreased while the patients ingested the high-fiber diets and rose when the fiber content of the diet was reduced.
Label source:
Primary literature: https://pubmed.ncbi.nlm.nih.gov/1335461/
Action type:
separate
Target id:
/condition/sibo
Target name:
Small Intestinal Bacterial Overgrowth (SIBO)
Severity:
moderate
Interaction type:
adverse
Nature:
absolute
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
PHGG is a highly fermentable prebiotic fiber. In individuals with SIBO, it can be rapidly fermented by overgrown bacteria in the small intestine, significantly worsening symptoms like gas, bloating, and pain.
Actionable advice:
PHGG is best avoided with active SIBO unless directed by a healthcare professional.
Validation status:
validated_via_pubmed
Evidence tier:
tier_b
Evidence basis:
pubmed_abstract_verbatim
Evidence anchors:
Exact phrase from label:
New open horizons can be glimpsed for SIBO treatment, lowering or maximizing the antibiotics use.
Label source:
PubMed: Minerva gastroenterologica e dietologica (2013)
Exact phrase from label:
It is a soluble, highly fermentable fiber with low viscosity. The fermentation of GGPH in colon produces short chain fatty acids, implicated in the main pathophysiological mechanisms responsible for their clinical effects.
Label source:
PubMed: Nutricion hospitalaria (2017)
Exact phrase from label:
The addition of pectin or guar gum to the glucose meal largely prevented postprandial symptoms and breath hydrogen excretion.
Label source:
PubMed: Scandinavian journal of gastroenterology (1983)
Action type:
avoid
Target id:
/intervention/low-fodmap-diet
Target name:
Low-FODMAP Diet
Severity:
moderate
Interaction type:
adverse
Nature:
absolute
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
Guar gum is a galacto-oligosaccharide (GOS), which is a type of FODMAP. It can trigger digestive symptoms in individuals with IBS who are sensitive to FODMAPs.
Actionable advice:
PHGG is best avoided during the elimination phase of a low-FODMAP diet.
Validation status:
validated_via_clinical_guidance
Evidence tier:
tier_b
Evidence basis:
clinical_guidance_verbatim
Evidence anchors:
Exact phrase from label:
Partially hydrolysed guar gum (PHGG): Existing studies indicate that PHGG may be well tolerated and helpful in people with both IBS-C and IBS-D, but more studies are needed. Has prebiotic properties, which may be beneficial for gut health.
Label source:
Clinical guidance: Monash University FODMAP — Fibre supplements and IBS
Action type:
avoid
Target id:
/dietary/water
Target name:
Water / Fluid
Severity:
major
Interaction type:
requirement
Nature:
temporal
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
PHGG is a soluble fiber that requires adequate fluid to dissolve properly and function effectively in the digestive tract, preventing clumping and potential discomfort.
Actionable advice:
Each dose of PHGG should be mixed thoroughly with at least 8 ounces (240 mL) of water or other non-carbonated fluid.
Validation status:
validated_via_primary_literature
Evidence tier:
tier_b
Evidence basis:
primary_literature_verbatim
Evidence anchors:
Exact phrase from label:
BACKGROUND AND AIM: Partially hydrolyzed guar gum (PHGG) is a water-soluble, non-gelling dietary fiber with a wide range of uses in clinical nutrition.
Label source:
PubMed: Partially hydrolyzed guar gum accelerates colonic transit time and improves symptoms in adults with chronic constipation. (PMID 24711073)
Action type:
informational_none
Target id:
/dietary/meal
Target name:
Any Caloric Meal
Severity:
minor
Interaction type:
synergistic
Nature:
temporal
Temporal spacing:
Hours before target:
0.25
Hours after target:
0
Description:
Taking PHGG with meals helps slow the digestion and absorption of carbohydrates and fats, which can help blunt post-meal spikes in blood glucose and improve satiety.
Actionable advice:
For blood sugar support, PHGG is best taken with a beverage just before or during meals.
Validation status:
validated_via_primary_literature
Evidence tier:
tier_b
Evidence basis:
primary_literature_verbatim
Evidence anchors:
Exact phrase from label:
Guar gum bread significantly reduced the postprandial rise in blood glucose, plasma insulin, and, except for bread containing low MW guar gum, plasma GIP levels compared to the control.
Label source:
PubMed: Effect of partially depolymerized guar gum on acute metabolic variables in patients with non-insulin-dependent diabetes. (PMID 9162612)
Action type:
separate
Target id:
/intervention/iron-supplements
Target name:
Iron Supplements
Severity:
minor
Interaction type:
diminishing
Nature:
temporal
Temporal spacing:
Hours before target:
2
Hours after target:
2
Description:
While PHGG is less likely to bind minerals than other fibers, there is a theoretical risk that it could slightly reduce the absorption of supplemental iron if taken at the same time.
Actionable advice:
As a precaution, separate doses of PHGG and iron supplements by at least 2 hours.
Validation status:
validated_via_primary_literature
Evidence tier:
tier_b
Evidence basis:
primary_literature_verbatim
Evidence anchors:
Exact phrase from label:
fiber supplements may reduce or delay your body's absorption of certain medications
Label source:
Primary literature: https://scielo.isciii.es/pdf/nh/v25n4/revision1.pdf
Action type:
separate
Target id:
/intervention/zinc
Target name:
Zinc Supplements
Severity:
minor
Interaction type:
diminishing
Nature:
temporal
Temporal spacing:
Hours before target:
2
Hours after target:
2
Description:
There is a theoretical possibility that soluble fiber could mildly interfere with the absorption of zinc supplements when consumed simultaneously.
Actionable advice:
To ensure maximal absorption, separate doses of PHGG and zinc supplements by at least 2 hours.
Validation status:
validated_via_pubmed
Evidence tier:
tier_b
Evidence basis:
pubmed_abstract_verbatim
Evidence anchors:
Exact phrase from label:
Generally, fiber and compounds associated with fiber in cereal products (e.g., phytates) have been found to reduce the apparent absorption of minerals (such as calcium, magnesium, zinc and manganese) in humans, livestock and animal models. The effects of "soluble" forms of fiber (specifically pectins, gums, resistant starches, lactulose, oligofructose and inulin) on mineral absorption are more difficult to characterize.
Label source:
PubMed: The Journal of nutrition (1999)
Exact phrase from label:
Zinc availability was highest after the addition of pregelatinized rice starch (13.5%) but lowest with the addition of locust bean gum (6.8%) and maltodextrin (5.4%).
Label source:
PubMed: Nutrition (Burbank, Los Angeles County, Calif.) (2003)
Exact phrase from label:
Both gums lowered iron and zinc availabilities, and guar gum affected iron availability more severely than locust-bean gum did.
Label source:
PubMed: Nutrition (Burbank, Los Angeles County, Calif.) (2001)
Action type:
separate
Target id:
/class/viscous-fibers
Target name:
Other Fiber Supplements
Severity:
minor
Interaction type:
adverse
Nature:
absolute
Temporal spacing:
Hours before target:
0
Hours after target:
0
Description:
Combining multiple fiber supplements (e.g., psyllium, inulin, PHGG) can lead to an excessive total fiber intake, increasing the likelihood of gastrointestinal side effects like gas, bloating, and cramping.
Actionable advice:
Introduce new fiber supplements one at a time and increase doses gradually to assess your individual tolerance.
Validation status:
validated_via_pubmed
Evidence tier:
tier_b
Evidence basis:
pubmed_abstract_verbatim
Evidence anchors:
Exact phrase from label:
WD produced the least gas during fermentation at 8, 12, and 24 h (P < 0.0001), while inulin produced the most by 8 h (P < 0.0001).
Label source:
PubMed: Nutrients (2013)
Exact phrase from label:
The principal aim of the study was to determine the short-term physiological effects and tolerability of the test fibres. In n = 10 female participants, post-prandial blood glucose, gastroparesis symptoms, and breath test measurements were recorded.
Label source:
PubMed: Nutrients (2021)
Exact phrase from label:
Significantly more patients switched from fiber to PHGG (49.9%) than from PHGG to fiber (10.9%) at four weeks.
Label source:
PubMed: Digestive diseases and sciences (2002)
Action type:
informational_none
Target id:
/intervention/calcium-citrate
Target name:
Calcium Supplements
Severity:
minor
Interaction type:
synergistic
Nature:
absolute
Temporal spacing:
null
Description:
By producing short-chain fatty acids (SCFAs) in the colon, PHGG can create a more acidic environment that improves the solubility and absorption of dietary and supplemental calcium.
Actionable advice:
Long-term, consistent use of PHGG may improve calcium absorption from all sources.
Validation status:
validated_via_class_inference
Evidence tier:
tier_c
Evidence basis:
class_inference_summary
Evidence anchors:
Source url:
Established mechanism / class pharmacology (no single primary source quoted)
Exact phrase from label:
Mechanistic inference: partially hydrolyzed guar gum is fermented to short-chain fatty acids that lower colonic pH, which can modestly improve solubility/absorption of some minerals such as calcium. Plausible, modest.
Label source:
Class inference
Action type:
informational_none