Quercetin: The lesser-known ingredient with big immune health promise

Nutritional OutlookNutritional Outlook Vol. 25 No. 6
Volume 25
Issue 6

Will new research on quercetin’s immune health properties revitalize interest in the ingredient?

Photo © AdobeStock.com/MQ-Illustrations

Photo © AdobeStock.com/MQ-Illustrations

The quercetin market is growing, driven by consumers’ renewed interest in immune health products in the wake of the COVID-19 pandemic. Brand Essence Research estimates that the global quercetin market will reach $406 million USD by 2027, with the Asia-Pacific region driving most of the growth.1

While quercetin has been on the market for some time, recent research on this flavonoid, and development activity, are giving rise to more potent formulations that are tailored for more specific end uses. Here are some of the ways quercetin is evolving to meet the needs of a more sophisticated market.

New Trials Show Surprising Benefits

Quercetin has shown a variety of effects on human health. Greg Ris, vice president of sales for Indena USA (Seattle, WA), says quercetin is best described as an antioxidant, anti-inflammatory, and immune health ingredient. As a flavonoid, he says, quercetin has an excellent antioxidant profile and can also modulate inflammation by acting on cytokines, NF-kB transcription factor, and pro-inflammatory enzymes.

One recent clinical trial2 found that quercetin had a surprising immunoprotective effect in a noteworthy environment. This 2021 randomized, controlled, open-label pilot trial sponsored by Indena and PharmExtracta S.p.A. (Italy) assessed whether PharmExtracta’s branded Quevir dietary supplement, containing Indena’s branded quercetin phytosome ingredient Quercefit, could shorten test-positivity duration, reduce risk of hospitalization, and modulate immune response in 42 adult outpatients who had tested positive for COVID-19 on a PCR test and were experiencing mild to moderate symptoms. Quercefit is a quercetin extract derived from Sophora japonica L. designed to be 20 times more bioavailable than unformulated quercetin.

Subjects were randomly assigned to receive either 1) a standard COVID-19 medical treatment protocol consisting of 500 mg/day of azithromycin for three consecutive days and up to 3 g/day of acetaminophen, or 2) the standard medical treatment protocol plus Quevir. The Quevir group received three 500-mg Quevir tablets per day for seven days, followed by two 500-mg Quevir tablets per day for another seven days. Each 500-mg Quevir tablet contains the equivalent of 200 mg of quercetin. Subjects were assessed for symptoms like fever, cough, headache, and weakness, as well as PCR test status, concentrations of immune biomarkers like C-reactive protein and lymphocytes, and need for hospitalization.

In this study, quercetin was found to accelerate viral clearance, reduce symptoms, and improve disease biomarkers in COVID-19 patients. While the trial had a small sample size, was not double-blind, and lacked a placebo condition, the authors concluded that quercetin improved clinical outcomes in COVID-19 outpatients.

Ris says quercetin may also have other immune benefits. In addition to its antioxidant properties, quercetin may inhibit cytokines and stimulate immune cells like lymphocytes.

“Indena recently completed a human study involving 120 high-exposure healthcare workers where individuals taking Quercefit were more likely to maintain their health in a high-risk COVID-19 environment3,” he notes. “We’re continuing our research into Quercefit for immune health, including daily immune function as well as allergies.”

R&D Leads to Improved Formulations

Quercetin ingredients have long suffered from formulation problems. Quercetin is often difficult to formulate in a bioavailable manner, has a challenging taste for formulators to work with, and lacks the solubility needed for certain applications. Recently, though, ingredient suppliers have overcome these formulation problems with creative new approaches.

Derek Timm, PhD, is the technical sales director for Taiyo International (Minneapolis). Timm says Taiyo resolved the issue of bioavailability by formulating a quercetin precursor. Launched in February 2022, Taiyo’s patented SunActive IsoQ is a water-soluble form of isoquercitrin extracted from the flower buds of the Styphnolobium japonicum Schott tree. SunActive IsoQ is a nature-identical isoquercitrin extracted through a patented enzyme process that is free of solvents. When converted into quercetin in the body, SunActive IsoQ becomes 25 times more bioavailable than free quercetin, the company says.

“SunActive IsoQ is produced with a novel delivery system that enables manufacturers to use a lower dose for health benefits,” Timm says. “It’s easily formulated in multiple delivery formats, such as beverages, gummies, powders, capsules, and soft chews.”

Michael Lelah, PhD, is the chief science officer for NutriScience Innovations LLC (Milford, CT). NutriScience is the exclusive U.S. distributor for SunActive IsoQ. Lelah explains that while the potential health benefits of quercetin have been known for some time, formulators have long struggled with the ingredient’s poor taste and bioavailability, making solutions like SunActive IsoQ key.

“Consumers need to trust that they’re receiving a health benefit from an ingredient,” Lelah adds. “They need to feel that benefit while also having an enjoyable experience.”

Low Consumer Awareness Constrains Growth

While new quercetin research has proven out new benefits and applications, brands continue to encounter hurdles in marketing and customer retention. Ris notes that, as is the case with many nutritional ingredients, low consumer awareness is limiting quercetin’s potential.

Despite quercetin’s various benefits, more consumer education may be needed in order for the ingredient to reach mass-market acceptance. Still, Ris says that new research on quercetin’s immune health properties has revitalized interest in the ingredient among suppliers and consumers. Brands looking to use quercetin in their formulations would do well to invest in consumer education campaigns.

Quercetin Development to Accelerate

The quercetin space is seeing new research and development activity as suppliers prove out the ingredient’s benefits. More bioavailable forms and formulations are creating new options for brands, while clinical trials examining quercetin’s properties are capitalizing on newsworthy applications like immune health. Incorporating quercetin as an ingredient in immune health blends may help to raise the ingredient’s profile and capture consumer interest.


  1. Brand Essence Research report. “Quercetin Market Size, Share & Trend Analysis Report by Type (Food Grade, Reagent/Chemical Grade, Others) by Nature (Organic, Conventional) by End Uses (Food & Beverage Industry, Pharmaceutical, Dietary Supplement & Nutraceutical, Others) Based on Region, and Segment Forecasts, 2021-2027.” Published online December 2021.
  2. Di Pierro F et al. “Potential clinical benefits of quercetin in the early stage of COVID-19: Results of a second, pilot, randomized, controlled and open-label trial.” International Journal of General Medicine. Published online June 24, 2021.
  3. Rondanelli M et al. “Promising effects of 3-month period of quercetin Phytosome supplementation in the prevention of symptomatic COVID-19 disease in healthcare workers: A pilot study.” Life, vol. 12, no. 1 (January 2022): 66
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