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Quercetin

  1. 1. Dietary Sources
  2. 2. Safety[2]
  3. 3. Healing Properties
    1. 3.1. Anti-Carcinogenic (anticancer)
      1. 3.1.1. Antiproliferative
      2. 3.1.2. Cancer chemopreventive agent
    2. 3.2. Anti-Inflammatory
    3. 3.3. Anti-Infective
    4. 3.4. Antioxidant
    5. 3.5. Brain Health
      1. 3.5.1. Neuroprotective
      2. 3.5.2. Neuroregeneration
        1. 3.5.2.1. Antioxidant
        2. 3.5.2.2. Anti-Inflammatory / Anti-Amyloid Fibrils
      3. 3.5.3. Cognitive performance
        1. 3.5.3.1. Memory Enhancer
        2. 3.5.3.2. Psychostimulant
    6. 3.6. Heart Health / Cardiovascular Health
      1. 3.6.1. Antiinflammatory
      2. 3.6.2. Anti-Atherogenic
    7. 3.7. Blood Health
    8. 3.8. Metabolism
      1. 3.8.1. Energy Production / Mitochondrial Health
  4. 4. Disease / Symptom Treatment
    1. 4.1. Cancer
      1. 4.1.1. Colorectal Cancer
    2. 4.2. Chronic Obstructive Pulmonary Disease (COPD)
    3. 4.3. Diabetes
    4. 4.4. Hyperuricemia
    5. 4.5. Sarcoidosis
    6. 4.6. SARS-CoV-2 / COVID-19
    7. 4.7. Neurodegenerative Diseases
      1. 4.7.1. Neuroinflammation
      2. 4.7.2. Alzheimer’s Disease (AD)
      3. 4.7.3. Parkinson’s Disease
        1. 4.7.3.1. Dopaminergic Neurodegeneration
      4. 4.7.4. Cognitive Impairment
      5. 4.7.5. Ischemia
      6. 4.7.6. Traumatic injury (brain/spinal)
      7. 4.7.7. Huntington’s disease
  5. 5. Synergistic Effects
    1. 5.1. Nicotinamide adenine dinucleotide (NAD+)
      1. 5.1.1. Cell Protection (Helps prevent DNA damage)

Quercetin is a plant flavonol from the flavonoid group of polyphenols. It is widely distributed among different fruits and vegetables.[1]

Dietary Sources

  • Pomegranate
  • Green tea
  • Red onion
  • Mango
  • Moringa oleifera
  • Blueberries
  • Chicory
  • Tomato
  • Apple
  • Passion Flower
  • White mulberry

Safety[2]

  • Poor aqueous solubility, extensive metabolism, and low oral bioavailability continue to limit clinical translation of quercetin.[3]
  • Poor bioavailability limits clinical use and encourages advanced drug delivery strategies.[3:1]
  • Future trials should validate standardized formulations, efficacy, and long-term safety.[3:2]

Healing Properties

Anti-Carcinogenic (anticancer)

Antiproliferative

Quercetin has demonstrated antiproliferative activity against colon and breast cancer cells.[4]

  • Treatment of quercetin had reduced the proliferation rates of colon HCT116 and breat MDA-MB-231 cancer cells.[4:1]

Cancer chemopreventive agent

Treatment with quercetin dihydrate has been shown to promote the killing activity of T cells on cancer cells.[5]

The growth rate of tumor volumes and masses treated with quercetin dihydrate were decreased.[5:1]

  • Quercetin regulates apoptosis and cell cycle progression through p53, PI3K/Akt, and mitochondrial signalling pathways, highlighting its relevance in cancer prevention and therapy.[3:3]
  • Quercetin modulates PI3K/Akt and Wnt/β-catenin signaling pathways among its multitarget actions.[3:4]

Anti-Inflammatory

Strong antiinflammatory activity.[1:1]

  • Quercetin exerts potent anti-inflammatory effects through modulation of multiple signalling pathways, including NF-κB.[3:5]
  • Inhibition of NF-κB and MAPK suppresses the production of pro-inflammatory mediators.[3:6]

Anti-Infective

  • Quercetin exhibits antiviral activity among its broad pharmacological effects.[3:7]
  • Clinical studies further suggest that quercetin may provide therapeutic benefits in SARS-CoV-2 infection, although results remain heterogeneous.[3:8]

Antioxidant

Quercetin is one of the most potent antioxidants of plant origin.[1:2]

Quercetin has direct radical scavenging action.[1:3]

  • Quercetin exerts potent antioxidant effects through modulation of multiple signalling pathways, including Nrf2, AMPK, and SIRT1.[3:9]
  • Activation of Nrf2, AMPK, and SIRT1 enhances endogenous antioxidant defenses and maintains cellular redox homeostasis.[3:10]
  • Quercetin modulates Nrf2, NF-κB, AMPK, SIRT1, PI3K/Akt and Wnt/β-catenin signaling pathways.[3:11]

Brain Health

Neuroprotective

Several in-vitro studies have reported that quercetin demonstrates neuroprotection.[1:4]

Quercetin’s metabolites after absorption have all been shown to afford neuroprotection as well.[1:5]

Quercetin protects against progressive dopaminergic neurodegeneration.[1:6]

Neuroregeneration

Quesrcetin stimulates neuronal regeneration.[1:7]

Antioxidant

It has been shown to protect neurons from oxidative damage while reducing lipid peroxidation.[1:8]

Anti-Inflammatory / Anti-Amyloid Fibrils

In addition to its antioxidant properties, it inhibits the fibril formation of amyloid-β proteins, counteracting cell lyses and inflammatory cascade pathways.[1:9]

  • Suppresses neuroinflammatory processes by downregulating pro-inflammatory cytokines.[1:10]
  • Prevents the degradation of acetylcholine, and decreases Aβ production.[1:11]

Cognitive performance

Quercetin restores acetylcholine levels through the inhibition of hydrolysis of acetylcholine by AChE enzyme.[1:12]

Memory Enhancer

Quercetin and rutin have been reported to function as memory enhancers in scopolamine-induced memory impairment tests, thus possibly enhancing cholinergic neurotransmission.[1:13]

Psychostimulant

Heart Health / Cardiovascular Health

Antiinflammatory

Quercetin Attenuates Atherosclerotic Inflammation[6]

Anti-Atherogenic

Quercetin inhibits atherogenesis (hardening/narrowing of the arteries).[6:1]

  • Clinical studies suggest that quercetin may provide therapeutic benefits in cardiovascular disease, although results remain heterogeneous.[3:12]

Blood Health

Inhibits platelet aggregation.[1:14]

Metabolism

Energy Production / Mitochondrial Health

Quercetin protects against mitochondrial dysfunction.[1:15]

Quercetin stimulates mitochondrial biogenesis.[1:16]

  • Quercetin ameliorates mitochondrial dysfunction by restoring mitochondrial membrane potential, decreases ROS production, and restores ATP synthesis.[1:17]
  • It also increases the expression of AMP-activated protein kinase (AMPK), which is a key cell regulator of energy metabolism.[1:18]
  • Quercetin modulates AMPK and SIRT1 signaling pathways relevant to cellular energy and redox homeostasis.[3:13]

Disease / Symptom Treatment

Cancer

Quercetin dihydrate has the exciting potential to be used as a cancer chemopreventive agent. Treatment with quercetin dihydrate has been shown to promote the killing activity of T cells on cancer cells.[5:2]

The growth rate of tumor volumes and masses treated with quercetin dihydrate were decreased.[5:3]

Colorectal Cancer

A systematic review and meta-analysis of preclinical studies found that quercetin exerts beneficial effects across multiple facets of colorectal cancer (CRC) treatment.[7]

  • Quercetin treatment significantly reduced the incidence of CRC (SMD -1.22, p = 0.004) compared to control groups.[7:1]
  • Quercetin alleviated inflammation and oxidative stress in colorectal cancer models.[7:2]
  • Quercetin effectively improved the degree of crypt lesions and alleviated precancerous lesions (SMD -1.40, p = 0.02).[7:3]
  • Quercetin demonstrated significant inhibitory effects on tumor cell proliferation as determined by PCNA analysis (SMD -8.22, p < 0.00001).[7:4]

Chronic Obstructive Pulmonary Disease (COPD)

  • Clinical studies support benefits of quercetin in COPD, although results remain heterogeneous.[3:14]

Diabetes

  • Clinical studies support benefits of quercetin in diabetes, although results remain heterogeneous.[3:15]

Hyperuricemia

  • Clinical studies support benefits of quercetin in hyperuricemia, although results remain heterogeneous.[3:16]

Sarcoidosis

  • Clinical studies further suggest that quercetin may provide therapeutic benefits in sarcoidosis, although results remain heterogeneous.[3:17]

SARS-CoV-2 / COVID-19

  • Clinical studies further suggest that quercetin may provide therapeutic benefits in SARS-CoV-2 infection, although results remain heterogeneous.[3:18]

Neurodegenerative Diseases

Quercetin Disaggregates Prion Fibrils and Decreases Fibril-Induced Cytotoxicity and Oxidative Stress.[8]

  • A 2026 review reports neuroprotective activities of quercetin among its multitarget effects in oxidative stress-related and neurodegenerative conditions.[3:19]

Neuroinflammation

Reducing the neuroinflammatory events in microglia might afford a beneficial strategy for the prevention of the progression of inflammatory-mediated neurodegenerative disorders.[1:19]

Quercetin has been reported to have anti-inflammatory actions, and is a suitable candidate among phytochemicals for future studies on its efficacy to reverse neuroinflammation.[1:20]

Quercetin has been shown to inhibit neuroinflammation by reducing nitric oxide production, iNOS gene expression in microglia, the production of inflammatory cytokines, as well as a reduction in cytokine expression as reported from in vivo studies.[1:21]

Alzheimer’s Disease (AD)

  • Reverses histopathological hallmarks of AD[1:22]
  • Improves motor function[1:23]
  • Reduces α-synuclein fibrillization[1:24]
  • Reduces hippocampal neuronal cell death[1:25]
  • Improves synaptic plasticity[1:26]
  • Quercetin has shown therapeutic efficacy, improving learning, memory, and cognitive functions in AD.[1:27]
  • Quercetin administration reverses extracellular β-amyloidosis and decreases tauopathies, astrogliosis, and microgliosis in the hippocampus and amygdale, thus protecting cognitive and emotional function in age triple transgenic Alzheimer’s disease model.[1:28]

Quercetin interferes with the formation of neurotoxic oligomeric Aβ species and displays fibril destabilizing effects on preformed fibrillar Aβ, reversing Aβ-induced neurotoxicity.[1:29]

Parkinson’s Disease

Dopaminergic Neurodegeneration

Quercetin protects against progressive dopaminergic neurodegeneration.[1:30]

Cognitive Impairment

Ischemia

Traumatic injury (brain/spinal)

Isoquercetin improved motor functions in acute spinal cord injury.[1:31]

Huntington’s disease

Synergistic Effects

Nicotinamide adenine dinucleotide (NAD+)

Cell Protection (Helps prevent DNA damage)

Quercetin can significantly potentiate the cell protection and rescue effects of Nicotinamide adenine dinucleotide (NAD+).[9]

Quercetin has been independently shown to significantly protect cells from DNA-damaging agents and induced cell death.[9:1]

The NAD+ precursors Nicotinic acid and Nicotinamide, when administered with Quercetin significantly improved cell protection and rescue effects, plausibly due to increased intracellular NAD+ levels.[9:2]

  1. Title: Neuroprotective Effects of Quercetin in Alzheimer’s Disease
    Publication: MDPI Biomolecules
    Archive: archive, archive-mirror ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎

  2. Title: Safety Aspects of the Use of Quercetin as a Dietary Supplement
    Publication: Wiley Online Library: Molecular Nutrition & Food Research
    Archive ↩︎

  3. Title: From antioxidant to signal modulator: The expanding role of quercetin in human health
    Publication: Pharmacological Research - Natural Products
    Date: 2026/09/01
    Study Type: Review
    Author(s): Aman Kumar, Nayan Sood, Ritik Kumar Thakur, Nitin Singh, Rajneesh Kalyan, Preeti Patel, Balak Das Kurmi
    Abstract: Quercetin, a naturally occurring flavonoid widely distributed in fruits, vegetables, and medicinal plants, has attracted considerable attention as a safe and affordable therapeutic candidate for the prevention and management of lifestyle and age-related diseases. Extensive evidence demonstrates that quercetin exerts potent antioxidant, anti-inflammatory, antiviral, chemoprotective, and immunomodulatory effects through modulation of multiple signalling pathways, including Nrf2, AMPK, SIRT1, NF-κB, Wnt/β-catenin, and p53. Clinical studies further suggest possible benefits in COPD, sarcoidosis, hyperuricemia, cardiovascular disease, and SARS-CoV-2 infection, although results remain heterogeneous. Poor aqueous solubility, extensive metabolism, and low oral bioavailability continue to limit clinical translation.
    Source URL: https://www.sciencedirect.com/science/article/abs/pii/S2950199726003496
    DOI: 10.1016/j.prenap.2026.100836 ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎ ↩︎

  4. Title: Synthesis, Antiproliferative Activity and Radical Scavenging Ability of 5-O-Acyl Derivatives of Quercetin
    Publication: MDPI - Molecules
    Archive: archive, archive-mirror ↩︎ ↩︎

  5. Title: Quercetin inhibiting the PD-1/PD-L1 interaction for immune-enhancing cancer chemopreventive agent
    Publication: Wiley Online Library: Phytotherapy Research
    Archive ↩︎ ↩︎ ↩︎ ↩︎

  6. Title: Quercetin Attenuates Atherosclerotic Inflammation by Inhibiting Gal‐3‐NLRP3 Signaling Pathway
    Publication: Wiley Online Library ↩︎ ↩︎

  7. Title: The potential value of quercetin for colorectal cancer: a systematic review and a meta-analysis of preclinical studies
    Publication: Frontiers in Pharmacology
    Date: 2025/09/05
    Study Type: Systematic Review and Meta-Analysis (preclinical animal studies)
    Author(s): Duan, Xiucheng, Zhang, Liyuan, Liu, Fenye ↩︎ ↩︎ ↩︎ ↩︎ ↩︎

  8. Title: Quercetin Disaggregates Prion Fibrils and Decreases Fibril-Induced Cytotoxicity and Oxidative Stress
    Publication: MDPI - Pharmaceutics
    Archive: archive, archive-mirror ↩︎

  9. Title: Resveratrol and Quercetin Potentiate the Cell Protection and Rescue Effects of NAD+ Precursors in HEK293 Cells Challenged by DNA Damaging Agent, N-Methyl-N′-nitro-N-nitrosoguanidine
    Publication: Sage Journals: Natural Product Communications
    Date: September 24, 2021
    Archive ↩︎ ↩︎ ↩︎