Thorne Quercetin Phytosome Review
Thorne Quercetin Phytosome is presented as a plant-based antioxidant support product. The page describes it as a powerhouse antioxidant that supports healthy seasonal immune system function and promotes a healthy aging process for well-rounded daily wellness support. Each capsule contains 250mg of Quercetin Phytosome, a phospholipid complex made from sunflower. The serving size is one capsule, with 60 servings per container. The product is sold as a one-time purchase at $46 for 60 capsules, or at $41.40 with a subscription offering 10 percent off, with additional savings available for multiple subscriptions and optional delivery intervals. Quercetin is described as a flavonoid, a plant pigment found in fruits and vegetables such as apples, onions, berries, and tea. Flavonoids are said to function as antioxidants that seek out and neutralize free radicals, which the page links to daily oxidative stress, cellular damage, accelerated aging, and chronic health conditions. Thorne states that its Quercetin Phytosome offers the antioxidant benefits of a flavonoid along with immune-supporting properties and the ability to support a healthy inflammatory response. The page explains that quercetin is typically characterized by poor absorption into the bloodstream, which is why Thorne provides it as a phytosome. The phytosome technology is described as optimizing bioavailability, and the page claims the product is up to 20 times more bioavailable than quercetin extract alone, allowing a smaller amount to deliver maximum benefit. The product is recommended for anyone looking to support healthy immune function, those looking to promote recovery and a healthy inflammatory response in the respiratory tract, biohackers looking to optimize sirtuin function and decrease senescent cells, and anyone wanting to support a healthy aging process. Under immune support, the page says quercetin plays a role in moderating immune function by supporting various types of immune cells needed for an optimized immune response, supporting healthy seasonal immune system function, and helping to maintain a normal inflammatory response, particularly in the respiratory tract. Under healthy aging, the page cites research showing quercetin helps reduce cellular senescence, a process in which malfunctioning cells stop dividing but do not die and remain in the body, which can be associated with biological aging and age-related disorders. The page states that quercetin is one of only two nutrients studied to reduce cellular senescence and that it up-regulates sirtuins, key regulators of cellular health associated with improved weight-related metabolic factors at the cellular level. The page describes the trio of antioxidant, sirtuin, and senescence support as helping to optimize healthy cellular aging. The product is stated to be third-party tested and certified to verify that what is in the package matches the label and that it contains no unsafe levels of contaminants such as heavy metals, pesticides, and microorganisms. The warnings section states that the product is contraindicated in individuals with a history of hypersensitivity to any of its ingredients, advises pregnant users to consult a health-care practitioner before use, and notes that there are no known adverse interactions or contraindications at the publication date.
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Study, Trial or Testing Result Summary
Members Only19 human studies · 9 improved
1 of these 19 human studies gave quercetin by injection, not by mouth.
The largest and best studies of quercetin taken alone did not show it strengthens the immune system. In 1002 adults taking 500 or 1000 milligrams daily for 12 weeks, colds and other upper airway infections were no less common than on placebo, though fit adults aged 40 and over on the higher dose had fewer sick days and milder illness [1]. In 120 women over 12 weeks, immune cell activity and inflammation did not change [2]. In 63 ultramarathon runners, illness rates matched placebo [3]. Four weeks of quercetin before a booster vaccine did not improve antibody or immune cell responses in 50 adults [4]. A lower dose of 150 milligrams for 6 weeks did not produce reproducible changes in immune cell genes [5]. One small trial of 40 trained cyclists did find fewer infections after heavy training, 1 of 20 versus 9 of 20 on placebo [6]. This product gives 250 milligrams per capsule, below the 500 to 1000 milligrams used in most of these trials. Animal and cell studies are never counted.
See all 19 studies →Hide the studies
- A review of 58 human studies on flavonoids and immune function found only quercetin had been tested as a supplement and said more evidence is needed to know whether it helps immunity.Flavonoids and immune function in human: a systematic review.
- A review of 48 trials and 10 observational studies on supplements for hay fever found promising evidence for isoquercitrin and for a vitamin D3, quercetin and Perilla mix, though the evidence quality was limited.Health supplements for allergic rhinitis: A mixed-methods systematic review.
- A review of lab and clinical studies on rheumatoid arthritis described quercetin as blocking an inflammation-linked enzyme and restoring immune cell balance, calling it a promising candidate, but no pooled human results were given.Mechanistic role of quercetin as inhibitor for adenosine deaminase enzyme in rheumatoid arthritis: systematic review.
- In 1002 adults aged 18 to 85 taking 500 or 1000 mg quercetin daily for 12 weeks, upper respiratory infection rates did not differ from placebo, though fit people aged 40 and over taking 1000 mg had fewer sick days and milder illness.Quercetin supplementation and upper respiratory tract infection: A randomized community clinical trial.
- In 194 matched COVID-19 patients, an herbal granule formula that contains quercetin among other compounds shortened lung lesion and viral clearance time and lowered inflammation markers, but quercetin was not tested alone.Yindan Jiedu granules exhibit anti-inflammatory effect in patients with novel Coronavirus disease (COVID-19) by suppress…
- In 120 women taking 500 or 1000 mg quercetin daily for 12 weeks, blood quercetin rose but natural killer cell activity, immune cell function and inflammation markers did not change compared with placebo.A 12-week supplementation with quercetin does not affect natural killer cell activity, granulocyte oxidative burst activ…
- In 63 ultramarathon runners taking 1000 mg quercetin daily for 3 weeks before and 2 weeks after a 160-km race, illness rates and immune cell and saliva antibody drops did not differ from placebo.Post-160-km race illness rates and decreases in granulocyte respiratory burst and salivary IgA output are not countered …
- In 50 older or metabolically at-risk adults, 560 mg of quercetin glycoside daily for 4 weeks before a COVID-19 booster did not change antibody or T-cell responses or vaccine reactions compared with placebo.Immune Preconditioning with Oral Quercetin Supplement and COVID-19 mRNA Vaccine Responses: A Randomized, Double-Blind, P…
- In 48 overweight or obese women, 10 weeks of a mixed supplement including 1000 mg quercetin did not change blood inflammation markers or cytokines, but increased activity of antiviral gene pathways and reduced inflammatory phagocytosis-related pathways compared with placebo.A Mixed Flavonoid-Fish Oil Supplement Induces Immune-Enhancing and Anti-Inflammatory Transcriptomic Changes in Adult Obe…
- In 40 trained male cyclists, 1000 mg of quercetin daily for 3 weeks before, during and 2 weeks after 3 days of heavy cycling did not change exercise-related immune measures but cut upper respiratory infections in the 2 weeks after (1 of 20 versus 9 of 20 on placebo).Quercetin reduces illness but not immune perturbations after intensive exercise.
- In 40 children aged 5-12 with allergic asthma and rhinitis, 6 months of a multi-ingredient supplement including quercetin improved asthma and nasal symptom control versus placebo and shifted immune cell responses in lab tests, though quercetin's own effect cannot be separated.Exploratory pilot trial of a multicomponent immunonutritional supplement in children with allergic asthma and rhinitis: …
- In 39 trained cyclists, 2 weeks of 1000 mg quercetin plus 120 mg EGCG daily lowered inflammatory markers CRP and IL-6 after 3 days of heavy exercise compared with placebo and increased an immune cell activity measure.Effects of quercetin and EGCG on mitochondrial biogenesis and immunity.
- In a small placebo-controlled pilot trial, young children with cow's milk allergy who took a multicomponent supplement containing quercetin for 6 months gained more weight and height than those given placebo, and their immune cells showed a shift toward tolerance.Immunonutritional effects elicited by a novel multicomponent food supplement in children with cow's milk allergy: result…
- In a crossover trial of 20 adults with a cardiovascular risk profile, 150 mg of quercetin daily for 6 weeks did not produce reproducible changes in monocyte gene expression compared with placebo; the few gene changes found were very small.Quercetin supplementation and its effect on human monocyte gene expression profiles in vivo.
- In a crossover trial of 20 runners, a single 1000 mg quercetin-based chew taken before a 2-hour run raised blood quercetin strongly but did not reduce exercise-induced inflammation or immune changes compared with placebo.The acute effect of ingesting a quercetin-based supplement on exercise-induced inflammation and immune changes in runner…
- In 356 young adults with hepatitis A, those given quercetin along with other drugs during the acute phase, in addition to standard care, showed better clinical and immune test results, though the quercetin effect could not be separated from the other drugs.[The immunocorrective therapy of patients with viral hepatitis A living under the adverse conditions of an industrial re…
- In 134 dysentery patients given injected quercetin and vitamin E for 7 days versus 154 on routine treatment, clinical signs normalized faster and immune balance was restored better.[The efficacy of quercetin and tocopherol acetate in treating patients with Flexner's dysentery].
- Cancer patients on personalized diets with added functional foods, including garlic, onion, and turmeric, had higher albumin and lower clotting marker levels, and one group also showed reduced markers of oxidative stress; the diets were not compared against a placebo and quercetin was not dosed separately.Read the study on PubMed (26333154) →
- In lab and mouse experiments, quercetin reduced production of the inflammatory signal TNF-alpha through a protein called Slpi, and oral quercetin raised Slpi levels; this was not tested as a treatment in people.Secretory leukoprotease inhibitor is required for efficient quercetin-mediated suppression of TNFα secretion.
Review Totals and Summary
Members Only7,094 reviews · 95% positive
Buyers of Thorne Quercetin Phytosome capsules are mostly positive, with about 5,782 ratings across the stores. Praise centres on energy, sleep, allergy-type relief and quality, and the main complaint is that it costs a lot. I left out review [4], which describes a different product combination, and review [1], which says nothing useful about the capsules. **What buyers say it did for them:** Many describe more energy and better sleep. One says, "Bye bye naps! Noticeable energy increase!" Another reports, "my sleep has been amazing," and adds that recovery from workouts improved. A few mention better workouts or focus. Others point to allergy and sinus effects: one person with MCAS says "One a day is like a little miracle for me," and another says it "helps keep my sinuses in good shape." A Vitacost-page reviewer also says it works well for their MCAS, without detail. Some are lukewarm: "After 60 days, have no proof of change." **What they complain about:** Price is the main complaint. Reviewers call it "Very Expensive" and "Pricey and not strong enough," with one suggesting the dose should reflect recent research. Another calls an ingredient "Sketchy." One buyer ordered the wrong pills by mistake. That was an ordering error, not a problem with the product. A few doubt whether it works noticeably. **Taste, smell, pill size or form:** Taste and smell are not discussed. On the Vitacost page, one reviewer says the capsules are very easy to swallow, and another says they fit easily into a daily routine. One buyer values the "clean" formulation, though the reviews don't say what that means. **Value for money:** Opinion is split. The store summaries note that the brand costs more, but one reviewer says it works and accepts the higher price. Another calls it good value for the size. Critical reviewers feel the price is too high for what they get: "Expensive." **Who it seems to suit and who it did not:** It seems to suit long-term, repeat buyers. One says "I have been using this product for years," another has taken it for about a year, and a third is on a third bottle. It also appeals to people who want a clean quercetin, such as the buyer who stopped using a caffeinated pre-workout, and to people looking for allergy, sinus or MCAS support. It suited people less if they expect a clearly noticeable change within a couple of months, or if they are price-sensitive and want a higher dose for the money. **Quality:** Store summaries say reviewers are happy with the quality and ingredients and trust the brand. There are no direct quotes for this theme. Overall, satisfied long-term users outnumber critics, and those critics mostly focus on price and on how little they noticed.
Biohacker Summary
Members Only4 of 10 recommend it
Quercetin is the main ingredient here, and the panel is broadly positive: eight of ten spoke about it, and most either recommend it or take it themselves. Their reasons are calming mast cells and histamine for allergies, clearing aged cells for longevity, easing inflammation, and supporting recovery and immune health. Several get it from foods like capers and onions, one takes the phytosome form, and one takes 250 mg once a month for three days. One says it pairs well with bromelain for absorption, and another uses an IV form every few months followed by a med. Cautions come from two panelists who say quercetin may interfere with alcohol breakdown, one who says it did not show huge effects in tests, and two who note there are no human trials yet on clearing aged cells and that much of the mast cell evidence comes from animals.
See all 9 biohackers →Hide the biohackers
Siim Land · Quercetin · neutral
- Mentions quercetin as a phytochemical that has been shown to stimulate GLP-1 expression directly, and also increase glucose uptake and insulin sensitivity.
- Uses IV quercetin every 3 months or so as part of his senolytic regimen, followed by a med.
- Mentions that Quercetin is one of the most common senolytics, but there are no human clinical trials on these yet.
- Did not see huge effects from quercetin in their tests.
- Discusses Quercetin as a senolytic supplement with potential longevity effects, but notes there are no human clinical trials yet to confirm its efficacy, placing it in the 'okay' tier based on current limited evidence.
- Mentions quercetin as a senolytic compound that helps eliminate senescent cells, which accumulate during aging and spread inflammation.
- The absorption rate for quercetin is around 1-3%, which is even lower than pure PCC1, explaining why much bigger doses are needed.
- Warns that quercetin, as a senolytic, can block MAOA, potentially raising adrenaline and causing anxiety or poor sleep in some individuals.
- Places Quercetin in the 'okay tier' for longevity, acknowledging its senolytic properties and potential life extension effects in animals, but highlights the limited human data on its effectiveness and the lack of established protocols for its use.
- Notes that quercetin, a flavonoid found in many fruits and vegetables, when combined with a med, was shown to induce senolysis or death of senescent cells in culture.
Thomas DeLauer · Quercetin · neutral
- Describes quercetin as 'unreal' and notes its high presence in apples and onions, stating it stabilizes mast cells to release less histamine.
- States that capers are the highest quality and most potent source of quercetin, which has huge impacts as an antioxidant and helps upregulate natural antioxidants in the body.
- Recommends quercetin as a polyphenol to be consumed in the evening, stating it's a great one that extends the repair window by inhibiting mTOR and acting as an HDAC inhibitor.
- Personally takes quercetin supplements because quercetin is awesome, and notes it is found in high concentrations in capers and also in maple syrup.
- States that quercetin is currently their favorite supplement in the longevity space, citing its performance properties for recovery, immune benefits, and its role as a powerful senolytic and anti-inflammatory that can be taken at any age.
- Notes that quercetin, found in polyphenol-rich foods like onions, shallots, and capers, can increase in skeletal muscle, allowing glucose to be absorbed into muscle cells without insulin.
- Notes that quercetin, which is in red onion, didn't perform as well as red onion itself in studies but still had a powerful benefit for fat loss.
- Mentions that bee pollen contains quercetin, which can help with the NRF2 pathway and the upregulation of the body's natural antioxidants like superoxide dismutase and glutathione.
- Started taking about 1,000 milligrams of quercetin every day, finding it acts as a potent histamine blocker, which helps him breathe better and feel more rested, especially at night due to congestion from allergies and histamine sensitivities.
- Mentions quercetin as a flavonol found in maple syrup that is great for allergies and has been demonstrated in other studies to reduce inflammation directly, including lipopolysaccharide-induced inflammation.
Dr. Eric Berg · Quercetin · recommends
- Dr. Eric Berg recommends adding more quercetin-rich foods such as red onions, capers, kale, dill, and radishes to your diet for seasonal allergies.
- Explains that the quercetin in onions decreases DHT, a powerful form of testosterone that is often the reason for hair loss.
- Lists quercetin as an epigenetic factor that may help with cancer prevention.
- Recommends quercetin-rich foods like onions, broccoli, and capers, as they support a healthy inflammatory response and help protect cells from oxidative stress for kidney health.
- Suggests that quercetin can be beneficial to counter some of the effects of a hypoxic state in cancer and inflammation.
- Recommends quercetin, found in onions, for kidney health.
- States that quercetin has great properties for the kidney, including anti-inflammatory effects and preventing scar tissue.
- States that quercetin is very beneficial for building up antioxidant reserves.
- Recommends quercetin as a way to get iron out of tissues, with onions being one of the best sources.
- Recommends quercetin, found in onions, as a food that can increase NAD and should be part of a healthy diet for people over 50.
Dave Asprey · Quercetin · recommends
- Recommends quercetin, found in foods like capers and red onions, as a plant compound that directly slows down the demolition crew inside cells, which destroys NAD+.
- Dave Asprey recommends quercetin, a plant compound found in capers and red onions, as it has been shown to directly slow down the demolition crew inside cells that breaks down NAD+.
- Believes quercetin is important for addressing mast cell activation.
- Sees great success with quercetin as a mast cell stabilizer.
- Recommends quercetin as a strategy to decrease inflammation, particularly post-COVID anxiety.
- Dave Asprey mentions that supplements like quercetin rival pharmaceuticals in keeping uric acid under control.
- Mentions that something as simple as quercetin could make a big difference in IQ if histamine is holding it down.
- Mentions that quercetin has anti-parasitic properties and is useful.
- Dave states that pure quercetin is not well absorbed orally because it never existed in isolated form in nature, making rutin a better option.
- Lists quercetin as a mass cell stabilizer that works well for treating Mass Cell Activation.
Dr. Mark Hyman · Quercetin · uses
- States that he uses Quercetin, a flavonoid and one of the best-studied natural mast cell stabilizers, for allergies and as a longevity compound, noting it pairs well with bromelain for absorption.
- Mentions that HTB Immune Energy Chews contain over 100 immune active polyphenols like quercetin, which are studied for supporting healthy immune balance and longevity.
- Notes that quercetin is one of the immune active polyphenols found in sprouted Himalayan tardy buckwheat, studied for supporting healthy immune balance and longevity.
- Dr. Mark Hyman, agreeing with the guest, mentions Quercetin as a supplement that can help with modifying the histamine response.
- Recommends quercetin, a natural mast cell stabilizer and plant bioflavonoid, to help stabilize mast cells that release histamine, which causes allergy symptoms.
- Recommends quercetin, a polyphenol from onion skins, as part of a 4 or 5-day senolytic intervention to kill zombie cells and lower the burden of toxic, pro-inflammatory cells.
- Uses Himalayan tartary buckwheat sprout powder daily, which is high in quercetin, and recommends quercetin for its antiviral, anti-inflammatory, anti-cancer, and antioxidant properties, noting its effectiveness against COVID-19 and its ability to reverse biological age.
- Recommends quercetin, stating it is a mast cell stabilizer, helps the body excrete uric acid, is great for longevity, works on AMPK, and can help lower uric acid and improve fatty liver.
- Recommends focusing on foods naturally rich in quercetin, such as onions and apples, and also adding quercetin supplements, due to their natural a med qualities.
- Recommends pairing high-dose IV vitamin C and L-lysine with a lot of antiviral supplements, including quercetin, to have as much antiviral fighting capacity on a daily basis as possible.
Ben Greenfield · Quercetin · uses
- States that quercetin inhibits proteasome, which has an effect on Nrf2 activation.
- Mentions quercetin or other senolytics to clear senescent cells as a recommended intervention on the True Age test.
- States that quercetin, a powerful flavonoid, is found in fruit tree leaves and was named after its inclusion in oak tree leaves.
- Mentions quercetin as a polyphenol that can confer benefits when consumed.
- Includes quercetin in their Lumat blue product along with methylene blue, phycocyanin, riboflavin, green tea extract, and lutein.
- Ben Greenfield mentions quercetin as an exercise mimetic.
- Mentions that a report for a client with high gut inflammation suggested using quercetin.
- Mentions quercetin as an example of a senolytic agent that helps get rid of senescent cells.
- Expresses caution about quercetin, noting it is an anti-cancer drug with antimitotic activities, and questions how hard one should push the body for extra years compared to living a good lifestyle.
- Recommends layering in quercetin to support antioxidant stores, especially for those with high oxidative loads.
Peter Attia · Quercetin · warns
- Quercetin, a bioactive flavonoid present in red wine, can impair alcohol metabolism.
- Notes that Quercetin is often given in combination with a med as an anti-senescent drug.
- Mentions that quercetin, found in fruits and onions, was one of the first two plant molecules discovered to activate human sirtuin one, alongside piceatannol, before resveratrol was identified.
- Takes 250 mg of Quercetin once a month for 3 days for longevity.
- Identifies Quercetin as a flavonoid compound and senolytic, often used with a med, and details its dosage in a pilot study for mild cognitive impairment or early-stage AD.
Dr. Rhonda Patrick · Quercetin · neutral
- Discusses a hypothesis that quercetin 3-glucuronide, a derivative of quercetin present in red wine, may cause red wine headaches by inhibiting an enzyme responsible for metabolizing acetaldehyde.
- Discusses quercetin, a flavonoid found in various plants, noting its reported ability to block the entry of SARS-CoV-1 in host cells and its potential role as a zinc ionophore, with clinical trials for SARS-CoV-2 beginning.
- Mentions quercetin, found in onions, as a plant polyphenol that has hormetic effects.
- Has supplemented with quercetin, particularly during COVID-19 for its antiviral properties, and now has the phytosome form from Thorne, which she might take again due to its anti-inflammatory and senescence effects.
- States that flavonoids like quercetin inhibit mast cell activation and histamine release, but much of the evidence is from animal work.
- Dr. Rhonda Patrick mentions that quercetin has been reported to block the entry of SARS-CoV-1 into host cells.
- Quercetin functions as a polyphenolic antioxidant, donating electrons and upregulating endogenous antioxidant enzymes to neutralize ROS.
- Notes that quercetin, found in yellow onions, activates FOXO3, which is associated with longevity.
Andrew Huberman · Quercetin · uses
- Takes quercetin supplements, noting that it activates sirtuins and helps kill senescent cells, contributing to longevity.
RAL Summary
Members OnlyTier 4 for Immune Health
Tier 2 rests on positive trials that were mostly mixed formulas, while the largest and best trials of quercetin alone (1002, 120, 63 and 50 people) found no immune benefit and only one small trial of 40 cyclists was positive, so the evidence is mixed at best. So it is graded Tier 4, lower than the rules alone gave.
- Emerging: not enough evidence to rank higher yet.
Where the evidence disagrees: 6 of the 19 human studies found no effect.
More Details
Members OnlyBody systems · Combine with · Possible side effects
Body systems: Immune system, Respiratory system
Combine with: For immune and allergy support, quercetin pairs well with vitamin C (which helps recycle quercetin and supports immune function), zinc, vitamin D3 with K2, and bromelain (which may improve quercetin absorption and adds anti-inflammatory support). Nettle leaf extract can complement it for seasonal allergy comfort. If joint health is still the user's goal, stack it with proven joint ingredients such as UC-II undenatured collagen, glucosamine with chondroitin, curcumin phytosome, omega-3 fish oil (EPA/DHA), and MSM. Take quercetin with a meal containing some fat and consult a healthcare provider if on meds, meds, or immunosuppressants, since quercetin can interact with some medications.
Possible side effects: No major side effects reported in the studies; quercetin did not change vaccine reactions compared with placebo.
Supplement Facts
Quercetin Phytosome 250 mg
| Quercetin Phytosome | 250 mg | † |
Other ingredients: Leucine, Microcrystalline Cellulose, Hypromellose, Silicon Dioxide.
Directions: Suggested use: Take 1 capsule two to three times daily with meals or as recommended by your health-care practitioner.
Barcode (UPC) 693749004356 · Label source: NIH label database · Report a label change
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Graded November 5, 2026 by the Reverse Age Lab evidence engine, from human studies, real reviews and our biohacker panel. How we grade. Is this medical advice? No. Rala organizes the published evidence; go over any change with your doctor, especially if you take meds.
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