Quercetin supplementation may reduce COVID-19 severity


Quercetin, a flavonol not naturally present in the human body, is a polyphenol found in fruits and vegetables

Quercetin Phytosome supplementation, in combination with standard care, may improve the early symptoms of COVID-19 and help mitigate the infection’s severity. It also statistically shortens the timing of molecular test conversion from positive to negative. These are the results of two recently issued human studies1 based on data produced in the last 15 months for Indena’s Quercefit.

The company stresses it’s critical to follow local and international guidelines, and that individuals should contact a health professional if they experience any symptoms associated with COVID-19. It also advocates, however, that some botanical ingredients, including quercetin, can help modulate immune and inflammatory responses in those suffering from respiratory conditions.

“Starting from the mentioned evidences, we carried out a first prospective, randomised, controlled, and open-label study, in which in addition to standard care a daily dose of 1000 mg of quercetin Phytosome was investigated for 30 days in 152 COVID-19 outpatients to disclose its adjuvant effect in treating the early symptoms and in preventing the severe outcomes of the disease,” said Prof Ikram Ujjan, MBBS, Pro Vice Chancellor, Liaquat University of Medical and Health Sciences (LUMHS). “According to the results of this clinical research, the add-on therapy with quercetin Phytosome has significantly reduced the need (68.2%) and the length (76.8%) of hospitalisation, the need of non-invasive oxygen therapy (93.3%), the progression to intensive care units (none versus 8 subjects) and the number of deaths (none versus 3 subjects). Globally considered, using quercetin Phytosome as add-on therapy to standard care has reduced by 91.6% the days of hospitalisation”.

Quercetin, a flavonol not naturally present in the human body, is a polyphenol found in fruits and vegetables. It’s characterised by pharmacological properties including broad-spectrum antiviral, antioxidant, anti-inflammatory and immune-protective effects, Indena says, allowing it to potentially support patients with conditions where oxidative stress, inflammation and immunity are involved. These conditions include discomforts related to cardiovascular health, healthy ageing, bones and joint health, sport and physical activity, gut, and respiratory health2.

Like many botanical extracts and natural compounds, quercetin has naturally poor water solubility, diminishing its bioavailability and potential effectiveness. In the studies, researchers used Quercefit, Indena’s quercetin system which uses sunflower phospholipids (Phytosome), proven to increase the flavonol’s oral absorption up to 20-fold.

"As an Italian company, we are very proud to be part of such important international studies focused on a signature ingredient of Indena, such as quercetin phytosome,” said Stefano Togni, Corporate Director for Business Development and Licensing, Indena. “This is another step of the work Indena has been committing to since one hundred years, in order to support scientific research in the field of botanical active ingredients. Continuous investment in innovation and design of proprietary technologies for the quality, safety and efficacy of ingredients, are the pillars on which Indena has built its leadership in the botanical sector as well as its inspiration for the future business".


1. Di Pierro et al., Possible Therapeutic Effects of Adjuvant Quercetin Supplementation Against Early-Stage COVID-19 Infection: A Prospective, Randomized, Controlled, and Open-Label Study, International Journal of General Medicine 2021:14 2359–2366. https://www.dovepress.com/possible-therapeutic-effects-of-adjuvant-quercetin-supplementation-aga-peer-reviewed-fulltext-article IJGM https://pubmed.ncbi.nlm.nih.gov/34135619/

Di Pierro et al., Potential Clinical Benefits of Quercetin in the Early Stage of COVID-19: Results of a Second, Pilot, Randomized, Controlled and Open-Label Clinical Trial, International Journal of General Medicine 2021:14 2807–2816. https://www.dovepress.com/potential-clinical-benefits-of-quercetin-in-the-early-stage-of-covid-1-peer-reviewed-fulltext-article-IJGM

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2. Anand David AV, Arulmoli R, Parasuraman S. Overviews of biological importance of quercetin: a bioactive flavonoid. Pharmacogn Rev. 2016;10(20):84–89. doi:10.4103/0973-7847.194044)

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