Dr. Grey AI

Rhamnogalacturonan I

Rhamnogalacturonan I (RG-I) is a complex polysaccharide found in pectin (abundant in citrus peel, apples, carrots). Has immunomodulatory properties - can stimulate immune cells via complement activation and TLR signaling. Modified citrus pectin (MCP) contains RG-I and has some human research for heavy metal chelation and possibly cancer adjunct therapy. Limited research as isolated RG-I. Essentially a fiber component with immune-modulating potential.

Quick Answer

What it is

Rhamnogalacturonan I (RG-I) is a complex polysaccharide found in pectin (abundant in citrus peel, apples, carrots). Has immunomodulatory properties - can stimulate immune cells via complement activation and TLR signaling.

Key findings

  • Grade C: Heavy Metal Excretion
  • Grade C: Cold Symptom Severity
  • Grade C: NK Cell Activity

Safety

No specific caution or interaction language was detected in the current summary/outcome notes.

ℹ️ Quick Facts: Rhamnogalacturonan I

Quick Facts: Rhamnogalacturonan I

  • Best Evidence:Grade C
  • Conditions Studied:2
  • Research Outcomes:5
  • Key Effect:Acute Respiratory Infection (ARI)
Outcomes by grade:
A0
B0
C3
D2
2 conditions · 5 outcomes

Detailed Outcomes

|
C
Heavy Metal Excretion
Several human studies using Modified Citrus Pectin (which contains RG-I) have demonstrated increased urinary excretion of lead, arsenic, and cadmium. MCP is used as a gentle chelation therapy, though the contribution of RG-I specifically versus other pectin components is unclear.
3 studies
moderate↑Improves
C
Cold Symptom Severity
A single RCT (n=146) challenged healthy volunteers with rhinovirus-16 after 8 weeks of carrot-derived RG-I supplementation (0.3 or 1.5 g/day). cRG-I significantly reduced WURSS-21 symptom scores (p<0.001) and improved quality of life measures (p<0.01) compared to placebo, with 0.3 g/day showing the strongest effects.
moderate↓Improves
C
NK Cell Activity
In the same rhinovirus challenge RCT (n=146), cRG-I supplementation significantly increased CD107a-positive NK cell degranulation (p<0.001), indicating enhanced natural killer cell cytotoxic activity. Interferon-response gene expression was also upregulated in treated groups.
moderate↑Improves
D
Macrophage Activation
In vitro studies show RG-I activates macrophages via complement system and TLR signaling. A 2025 study in zebrafish and RAW 264.7 macrophages demonstrated that RG-I-enriched pectin dose-dependently enhanced macrophage phagocytosis, upregulated immune genes (TNF-alpha, IL-1beta, NF-kappaB), and restored gut microbiota in immunocompromised animals. No human data for this specific outcome.
small↑Improves
D
Cancer Progression
Modified Citrus Pectin (containing RG-I) inhibits galectin-3, a protein involved in cancer cell adhesion and metastasis. Preliminary human studies and preclinical data suggest possible benefit as adjunct cancer therapy, but research is early-stage and no well-powered clinical trials exist for this indication.
2 studies
small↓Worsens

Related Supplements

Zinc

1 shared condition · 148 outcomes

Zinc is an essential mineral that is critical for the function of hundreds of enzymes. Consequently, it plays many roles, including in antioxidant enzymes, brain function, and the immune system. Zinc is most commonly taken to reduce the duration of respiratory infections and the common cold.

Yeast Mannan

1 shared condition · 4 outcomes

Yeast mannan (mannan-oligosaccharides/MOS) is a polysaccharide from yeast cell walls. Indigestible by humans but fermented by gut bacteria, acting as a prebiotic. Used primarily in animal nutrition to support gut health and immunity. NO GRADED OUTCOMES in humans - research is mostly in animals. May have immune-modulating effects. Part of yeast beta-glucan/MOS products. Generally safe.

Vitamin D

1 shared condition · 308 outcomes

Vitamin D is a fat-soluble vitamin that our skin synthesizes when exposed to the sun. It benefits us in many ways, from bone health to mood.

Vitamin C

1 shared condition · 262 outcomes

Vitamin C, or ascorbic acid, is an essential vitamin and a very popular supplement due to its antioxidant properties, safety profile, and low price. Many people supplement with vitamin C because it is believed to reduce symptoms of the common cold.

Violet Flower

1 shared condition · 6 outcomes

Violet flower (Viola odorata) is traditionally used in Persian/Unani medicine for respiratory conditions like coughs and allergic rhinitis. Contains mucilage and anti-inflammatory compounds. NO GRADED OUTCOMES - research is limited. Some studies suggest benefits for allergic rhinitis symptoms. Generally safe as an herbal tea or syrup. More research needed to confirm traditional uses.

Umckaloabo

1 shared condition · 42 outcomes

Umckaloabo is a common name for the root extract of Pelargonium sidoides, a member of the geranium family. The most frequently studied use for umckaloabo is in the treatment of respiratory infection symptoms.

Spirulina

1 shared condition · 304 outcomes

Spirulina, commonly known as “blue-green algae”, is a nontoxic cyanobacterium that is rich in various nutrients and bioactive pigments and polyphenols. Spirulina contains many antioxidant compounds and could have beneficial cardiometabolic effects.