Quercetin
Synopsis of quercetin
Quercetin is a plant-derived flavonoid found abundantly in fruits, vegetables, and herbs, especially in onions, apples, capers, berries, kale, and green tea. It is one of the most researched flavonoids for its potent antioxidant, anti-inflammatory, antihistamine, and immune-modulating properties. Quercetin helps neutralize free radicals, protect cells from oxidative damage, and regulate immune responses, making it beneficial for a wide range of health concerns.
Quercetin inhibits the production and release of histamine, prostaglandins, and leukotrienes, which makes it highly effective for allergy relief, including hay fever, asthma, eczema, and mast cell activation syndrome (MCAS). It is also used to support cardiovascular health, reduce inflammation, and enhance exercise performance and recovery. Some studies suggest quercetin may help improve blood vessel function, lower blood pressure, and support metabolic and mitochondrial health.
It is often taken in supplement form—sometimes paired with vitamin C or bromelain to enhance absorption—and is used in protocols for long COVID, immune resilience, and respiratory infections, as well as for neuroprotection and longevity.
Historical Use:
While quercetin as an isolated compound was first identified in the 1930s, the use of quercetin-rich plants in traditional medicine spans thousands of years. In Traditional Chinese Medicine (TCM) and Ayurveda, plants like onion, hawthorn, and tea—now known to be high in quercetin—were used to treat inflammation, allergies, infections, and heart conditions.
In European herbal traditions, elderberries, buckwheat, and St. John’s wort were employed for colds, circulation, and skin issues—all attributed today in part to their flavonoid content. Onions were a folk remedy for respiratory conditions and immune support, while apples and berries were widely used for fever and gut health.
With the advent of modern nutritional science in the 20th century, quercetin was isolated, studied, and eventually recognized as one of the most bioactive and multifunctional flavonoids. Today, it is a cornerstone ingredient in natural antihistamine protocols, inflammation management, and immune-supportive therapies, valued both for its broad safety profile and wide-ranging effects on cellular health.
Quercetin is used for these health conditions
Aging (prevention) (Scientific)
Allergies (food) (Scientific)
Allergies (respiratory) (Scientific)
Alzheimer's Disease (Scientific)
Arteriosclerosis (Scientific)
Arthritis (Scientific)
Asthma (Scientific)
Autoimmune Disorders (Scientific)
Bladder (ulcerated) (Scientific)
Blood Clots (prevention of) (Scientific)
Bruises (healing) (Traditional)
Cancer (natural therapy for) (Scientific)
Cancer (prevention) (Scientific)
Capillary Weakness (Scientific)
Cardiovascular Disease (Scientific)
Cartilage Damage (Scientific)
Cataracts (Scientific)
Chemotherapy (reducing side effects) (Scientific)
Cholesterol (high) (Scientific)
Chronic Obstructive Pulmonary Disorder (Scientific)
Circulation (poor) (Scientific)
Circulation (to the brain) (Scientific)
Cirrhosis of the Liver (Scientific)
Cold Sores (Scientific)
Colds (antiviral) (Scientific)
Colds (decongestant) (Scientific)
Colds (general) (Scientific)
Colds (prevention) (Scientific)
Colds (with fever) (Scientific)
Colitis (Scientific)
Congestion (Scientific)
Congestion (bronchial) (Scientific)
Congestion (lungs) (Scientific)
Congestion (sinus) (Scientific)
Conjunctivitis (Scientific)
Contagious Diseases (Scientific)
Cough (damp) (Traditional)
Crohn's Disease (Scientific)
Cystic Fibrosis (Scientific)
Cytomealovirus (Scientific)
Dementia (Scientific)
Depression (Scientific)
Dermatitis (Scientific)
Diabetes (Scientific)
Diabetic Retinopathy (Scientific)
Edema (Scientific)
Fatigue (Scientific)
Free Radical Damage (Scientific)
Gastritis (Scientific)
Gingivitis (Scientific)
Hair (loss or thinning) (Scientific)
Hypertension (Scientific)
Inflammation (Scientific)
Influenza (Scientific)
Irritable Bowel Syndrome (Scientific)
Liver Detoxification (Scientific)
Lupus (Scientific)
Memory and Brain Function (Scientific)
Multiple Sclerosis (Scientific)
Osteoporosis (Scientific)
Parkinson's Disease (Scientific)
Peripheral Neuropathy (Scientific)
Prostatitis (Scientific)
Psoriasis (Scientific)
Rhinitis (Scientific)
Rhinitis, Allergic (Scientific)
Sinus Infection (Scientific)
Skin (infections) (Scientific)
Sneezing (Scientific)
Triglycerides (high) (Scientific)
Ulcers (Scientific)
quercetin is used to support these body systems
Arteries (Scientific)
Blood (Scientific)
Brain (Scientific)
Capillaries (Scientific)
Circulatory System (Scientific)
Gastrointestinal Tract (Scientific)
Heart (Scientific)
Immune System (Scientific)
Intestinal System (Scientific)
Joints (Scientific)
Lungs (Scientific)
Mitochondria (Scientific)
Prostate (Scientific)
Respiratory System (Scientific)
Sinuses (Scientific)
Skin (Scientific)
Veins (Scientific)
