Quercetin

Quercetin

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Summary

Quercetin is a flavonoid polyphenol with antioxidant and anti‑inflammatory effects. In adults, supplementation may support immune balance, vascular function, and GI comfort; cognitive and mood effects are indirect through reduced inflammation and improved recovery.

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Quercetin Complex — Thorne
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Quercetin Complex
Combines quercetin phytosome and bromelain to support allergy sufferers, enhance immune function, and help reduce bruising and swelling. NSF Certified for Sport®.
thorne.com
 

Mental Clarity, Focus, and Energy

  • Indirect effects: Reduced inflammatory load and improved recovery can translate to steadier daytime energy and focus in some cohorts.
  • No stimulant‑like effects; benefits accrue over weeks.

Brain Health

  • Mechanisms: Modulates NF‑κB, supports mitochondrial function and redox balance, and may influence neurotrophic signaling in models.
  • Human cognition‑specific data are limited; most endpoints relate to fatigue, mood, or recovery.

Gut Health

  • May help reduce GI inflammatory signals and support barrier integrity in early human work; GI tolerability improves when taken with food.

Brain-Gut Axis

  • By decreasing oxidative and inflammatory signaling and potentially modulating microbiota metabolites, quercetin may indirectly support gut–brain communication.

Evidence Summary

Benefit Area
Evidence Quality
Effect Noted
Notes
Mental Clarity
Limited–Moderate
Indirect via inflammation/recovery
500–1,000 mg/day
Focus Enhancement
Limited
Secondary to improved recovery
Not a stimulant
Energy Support
Limited–Moderate
Reduced fatigue in subsets
Baseline inflammation matters
Brain Health
Moderate
Antioxidant and anti‑inflammatory support
Heterogeneous endpoints
Gut Health
Emerging–Moderate
Barrier and GI comfort signals
With food for tolerance
Brain–Gut Optimization
Emerging
Lower oxidative/inflammatory crosstalk
Early human signals

Typical Dosing Instructions

  • Standard dose: 500–1,000 mg/day, often split twice daily; consider phytosome forms for absorption
  • Timing: With meals to reduce GI upset; pair with vitamin C to support uptake
  • Notes: Evaluate after 4–8 weeks; avoid exceeding label dosing without clinician guidance

Safety Considerations

  • General safety: Generally well tolerated when taken with food
  • Common effects: GI upset or headache in some users
  • Contraindications and cautions: Potential interactions with certain antibiotics, cyclosporine, and CYP3A4‑metabolized drugs; theoretical antiplatelet effects
  • Populations: Limited pregnancy data; avoid unless clinician‑directed
  • Monitoring: Track GI comfort, fatigue, and recovery; discontinue if adverse effects occur
 

References

  1. The effects of quercetin supplementation on lipid profiles and inflammatory markers among patients with metabolic syndrome and related disorders: A systematic review and meta‑analysis of RCTs, 2019-04-23
  1. Quercetin: Its Main Pharmacological Activity and Potential Application in Clinical Medicine, Oxidative Medicine and Cellular Longevity, 2020-12-30
  1. The Effects of Quercetin on Vascular Endothelium, Inflammation, Cardiovascular Disease and Lipid Metabolism—A Review, 2025-05-03
  1. Two‑month 500 mg/day lecithin‑based quercetin supplementation counterbalances chronic fatigue symptoms: double‑blind, placebo‑controlled clinical trial, 2023-01-01
  1. Quercetin in Sports and Exercise: A review, International Journal of Exercise Science, 2023-10-01
  1. Quercetin, Inflammation and Immunity, Nutrients, 2016-04-01
  1. Modulatory Properties of Food and Nutraceutical Components Targeting NLRP3 Inflammasome Activation, Nutrients, 2022-01-23
  1. Quercetin Uses, Benefits & Dosage, Drugs.com, 2024-12-09