# Quercitrin (Quercetin 3-rhamnoside)

**Canonical URL:** https://ingredients.hermeticasuperfoods.com/ingredients/quercitrin
**Data Source:** Hermetica Superfoods Ingredient Encyclopedia
**Updated:** 2026-03-30
**Evidence Score:** 4 / 10
**Category:** Compound
**Also Known As:** Quercetin 3-rhamnoside, Quercetin-3-O-rhamnoside, 3-Rhamnosylquercetin, Quercetin 3-rhamnopyranoside, Quercitroside, Rhamnetin

## Overview

Quercitrin (quercetin 3-rhamnoside) is a flavonoid glycoside in which quercetin is bound to the sugar rhamnose, altering its solubility and metabolic profile compared to free quercetin. It exerts antioxidant, [anti-inflammatory](/ingredients/condition/inflammation), and [antiviral](/ingredients/condition/immune-support) effects primarily by inhibiting pro-inflammatory enzymes such as COX-2 and lipoxygenase, and by scavenging [reactive oxygen species](/ingredients/condition/antioxidant).

## Health Benefits

• May reduce upper respiratory tract infection severity by 36% and sick days by 31% in fit adults over 40 (based on quercetin studies, moderate evidence) • Potential [antiviral](/ingredients/condition/immune-support) activity shown in COVID-19 patients with faster viral clearance (76% vs 9.5% negative after 1 week, preliminary evidence) • May help prevent oral mucositis in chemotherapy patients (30% vs 60% incidence, preliminary evidence) • [Anti-inflammatory](/ingredients/condition/inflammation) effects demonstrated through reductions in CRP, D-dimer, and ferritin markers (preliminary evidence) • Well-tolerated at doses up to 2000 mg/day with no severe adverse events in COPD patients (moderate evidence)

## Mechanism of Action

Quercitrin inhibits cyclooxygenase-2 (COX-2) and 5-lipoxygenase, suppressing prostaglandin E2 and leukotriene B4 synthesis to reduce inflammatory signaling. It also downregulates NF-κB pathway activation, limiting transcription of [pro-inflammatory cytokine](/ingredients/condition/inflammation)s including TNF-α and IL-6. Additionally, quercitrin chelates transition metal ions involved in Fenton reactions, reducing hydroxyl radical formation and oxidative cellular damage.

## Clinical Summary

Most clinical evidence for quercitrin comes from trials using quercetin broadly, as quercitrin is a quercetin glycoside that undergoes partial conversion to quercetin aglycone after intestinal [metabolism](/ingredients/condition/weight-management). A randomized controlled trial in physically fit adults over 40 found quercetin supplementation reduced upper respiratory tract infection severity by approximately 36% and sick days by 31%, though sample sizes were modest. Preliminary clinical data from a COVID-19 study reported viral clearance in 76% of quercetin-supplemented patients versus 9.5% of controls after one week, but this was a small, early-phase study requiring replication. Overall, evidence is promising but largely moderate-quality, with larger controlled trials needed specifically examining quercitrin's distinct bioavailability profile.

## Nutritional Profile

Quercitrin (Quercetin 3-rhamnoside) is a flavonoid glycoside with molecular formula C21H20O11 and molecular weight of 448.38 g/mol. It is not a macronutrient source and contributes negligible caloric value. As a bioactive compound, it consists structurally of the flavonol aglycone quercetin bound to the sugar rhamnose (6-deoxy-L-mannose) at the 3-position. Typical concentrations in plant sources: found at 0.1–2.5 mg/g dry weight in buckwheat leaves, 0.5–3.0 mg/g in citrus peel (particularly lemon and lime), 0.2–1.8 mg/g in Rhus coriaria (sumac), and trace amounts (0.05–0.3 mg/g) in black tea and red wine. Bioavailability is notably lower than free quercetin aglycone due to the rhamnose moiety; intestinal absorption requires rhamnosidase enzyme activity primarily from colonic microbiota, resulting in delayed but sustained quercetin release in the large intestine. Estimated oral bioavailability is approximately 20–30% relative to quercetin aglycone. Once deglycosylated, quercetin undergoes hepatic methylation and sulfation, producing isorhamnetin and quercetin sulfates as primary circulating metabolites. No significant vitamin, mineral, fiber, or protein content is associated with purified quercitrin itself. Antioxidant capacity measured at approximately 2.5–3.0 mmol Trolox equivalents per gram (FRAP assay), slightly lower than free quercetin (~4.7 mmol TE/g) due to glycosylation reducing [free radical scaveng](/ingredients/condition/antioxidant)ing at the 3-OH position.

## Dosage & Preparation

Clinical studies of quercetin (released from quercitrin) used 500-1000 mg/day for 10-12 weeks for general health, up to 2000 mg/day for COPD patients, with powder or capsule forms being most common. No standardization specific to quercitrin content was detailed in trials. Consult a healthcare provider before starting any new supplement.

## Safety & Drug Interactions

Quercitrin is generally well tolerated at typical dietary and supplemental doses, with mild gastrointestinal discomfort (bloating, nausea) reported occasionally at higher doses above 500 mg/day quercetin equivalents. It may inhibit CYP3A4 and P-glycoprotein, potentially raising plasma concentrations of drugs such as cyclosporine, statins, and certain anticoagulants like warfarin, necessitating caution. Quercitrin may also potentiate the effects of antiplatelet agents due to inhibition of thromboxane A2 synthesis, increasing bleeding risk when combined with aspirin or clopidogrel. Safety data in pregnancy and lactation are insufficient, and use during these periods is not recommended without medical supervision.

## Scientific Research

While no quercitrin-specific human trials were identified, multiple RCTs have studied quercetin (the active form released from quercitrin). Key trials include a URTI prevention study in 1002 subjects (PMID: 20478383), a COVID-19 outpatient trial with 42 participants (PMID: 36712674), and safety studies in COPD patients testing doses up to 2000 mg/day (PMID: 32071149).

## Historical & Cultural Context

While no direct traditional use of quercitrin was documented in the research, quercetin-related compounds appear in Traditional Chinese Medicine formulas such as Bushen Yiqi Lixue Yangtai (BYLY) for recurrent spontaneous abortion. Quercitrin was identified as a potential key component among 132 active compounds in this traditional remedy.

## Synergistic Combinations

Vitamin C, Zinc, Vitamin D3, Bromelain, Green Tea Extract

## Frequently Asked Questions

### What is the difference between quercitrin and quercetin?

Quercitrin is quercetin bound to the monosaccharide rhamnose at the 3-position, making it a glycoside with lower water solubility than quercetin dihydrate but distinct intestinal absorption kinetics. After ingestion, gut microbiota and intestinal rhamnosidases cleave the rhamnose moiety, releasing free quercetin aglycone that enters systemic circulation. This glycosylation affects both the speed of absorption and the tissues where bioactive metabolites accumulate.

### What foods are naturally high in quercitrin?

Quercitrin is found in relatively high concentrations in rue (Ruta graveolens), capers, buckwheat, and certain citrus peels. It also appears in smaller amounts in apples, red onions, and green tea alongside related flavonoid glycosides like rutin and isoquercitrin. Rue is particularly rich but is also mildly toxic in large amounts, so food sources rather than herbal concentrates are generally preferred for dietary intake.

### How much quercitrin should I take per day?

There is no established recommended daily dose specifically for quercitrin, but clinical quercetin studies showing respiratory benefits typically used 500–1000 mg per day of quercetin equivalents divided into two doses. Because quercitrin must be converted to quercetin aglycone for much of its activity, dosing is often extrapolated from quercetin trials, and bioavailability can vary significantly with food intake and individual gut microbiome composition. Consulting a healthcare provider before supplementing above 500 mg quercetin equivalents daily is advisable, especially for those on prescription medications.

### Does quercitrin have antiviral activity against COVID-19?

Preliminary evidence from a small clinical study reported that quercetin supplementation was associated with SARS-CoV-2 viral clearance in 76% of patients after one week compared to only 9.5% in the control group, suggesting potential antiviral benefit. The proposed mechanism involves quercetin's ability to inhibit the 3CL protease of SARS-CoV-2 and interfere with viral spike protein binding to ACE2 receptors. However, these findings are early-phase and based on small sample sizes, meaning they should not be interpreted as established treatment evidence.

### Can quercitrin interact with blood thinners or other medications?

Yes, quercitrin and its aglycone quercetin can inhibit cytochrome P450 enzymes CYP3A4 and CYP2C9, which are responsible for metabolizing drugs including warfarin, cyclosporine, and several statins, potentially elevating their plasma levels and risk of adverse effects. Quercetin also inhibits thromboxane A2 synthesis via COX-1 suppression, which adds antiplatelet activity that may compound the bleeding risk of anticoagulants or antiplatelet drugs like aspirin and clopidogrel. Patients on any of these medications should consult a physician before starting quercitrin supplementation.

### What does clinical research show about quercitrin's effectiveness for respiratory infections?

Studies on quercetin (of which quercitrin is a glycoside form) suggest it may reduce upper respiratory tract infection severity by approximately 36% and shorten sick days by 31% in fit adults over 40, though this evidence is moderate quality and primarily based on quercetin rather than quercitrin specifically. The mechanism appears related to quercitrin's antiviral and anti-inflammatory properties, though more human trials directly testing quercitrin are needed to confirm these benefits.

### Is quercitrin safe for people undergoing chemotherapy or cancer treatment?

Preliminary research indicates quercitrin may help prevent oral mucositis (mouth sores) in chemotherapy patients, reducing incidence from 60% to approximately 30%, though evidence remains limited and early-stage. However, you should consult your oncology team before taking quercitrin during chemotherapy, as polyphenols can potentially interact with certain cancer medications or treatments.

### What affects how well my body absorbs quercitrin from supplements?

Quercitrin's bioavailability is influenced by its glycoside form, which may offer better absorption than aglycone quercetin in some individuals due to different intestinal transport mechanisms. Taking quercitrin with fat-containing meals and vitamin C may enhance absorption, while digestive health and individual gut microbiota variations can also affect how much quercitrin your body actually utilizes.

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