Respiratory well-being during allergy season

Indena’s Quercefit provides safe and effective benefits

Sophora japonica

Flavonoids are a natural treasure for human well-being, which is mainly derived from their antioxidant activity.1 They are able to both reduce free radical formation and scavenge free radicals. Quercetin, categorised as a flavonol, is one of the six subclasses of flavonoid compounds and is supported by extensive scientific literature that demonstrates its multiple biological activities (antioxidant, antiageing, antiaggregation and vasodilation).2–4

Among its different properties, quercetin has shown a promising role in respiratory health when allergies are rife. It’s able to act as a modulator of immune cells, such as lymphocytes, and the release of interferon-γ (IFN-γ). Quercetin can influence the activity of eosinophils by regulating eosinophil peroxidase. Furthermore, through the stabilisation of cell membranes, it can affect the release of histamine from mast cells, which causes sneezing, itchy eyes, a scratchy throat and itchy skin.

The management of healthy levels of antibody IgE, which releases chemicals that cause allergic symptoms, has a direct effect on those annoying reactions in the nose, lung, throat and skin. These positive actions support the promising use of quercetin for respiratory health. Additionally, quercetin has shown in vitro activity against multiple viral targets and, very recently, was identified as a promising ingredient against COVID-19.5 For this reason, quercetin is under evaluation in human clinical studies on COVID-19 subjects.

Indena’s Quercefit comprises quercetin deriving from the flower buds of Sophora japonica L., which is then formulated with Phytosome, Indena’s proprietary 100% food-grade delivery system. Quercefit, a highly bioavailable quercetin, recently achieved very interesting results for the maintenance of well-being in sensitive or intolerant subjects in two human studies.6,7

After 30 days of supplementation with one or two tablets per day of Quercefit, the subjects’ well-being and level of seasonal discomfort were evaluated using the GINA (Global INitiative for Asthma) classification system. Quercefit was shown to retain the normal parameters related to diurnal and nocturnal respiration (by 50% and 70%, respectively) with particular regard to breath function (Peak Expiratory Flow) in those with mild persistent discomfort. The supplementary use of Quercefit with the use of the best available remedies — all while optimising general comfort management and minimising oxidative stress — demonstrated a very good safety profile.6

In a second human study focusing on local skin discomfort, Quercefit was administrated for 3 days, prior to the administration of local histamine skin stimulus. Compared with the control, only the healthy volunteers supplemented with Quercefit showed a statistically significant dose-dependent control of all the main local skin conditions along with capillary filtration reduction.7

Moreover, Quercefit’s safety profile has been investigated in a preliminary human study looking for any interaction between quercetin formulated with Phytosome and common standard synthetic drugs, controlling any possible harmful effects.8 The promising results suggest that Quercefit might not alter the activity of the most common antiplatelet agents (acetylsalicylic acid, ticlopidine or clopidogrel), has no impact in stable subjects using warfarin or dabigatran and might not influence the metabolic control of glucose impairment.9


  1. A.N. Panche, et al., Journal of Nutritional Science 5 e47 (2016):
  2. N. Chondrogianni, et al., Exp. Gerontol. 45(10), 763–771 (2010).
  3. M. Chopra, et al., Clin. Chem. 46(8 Pt 1), 1162–1170 (2000).
  4. I. Erlund, et al., Eur. J. Clin Pharmacol. 56(8), 545–553 (2000). S. Khaerunnisa, et al., Preprints 2020 (doi: 10.20944/preprints202003.0226.v1).
  5. M.R. Cesarone, et al., Minerva Medica 110(6), 524–529 (2019).
  6. G. Belcaro, et al., Esperienze Dermatologiche 22(1), 5–9 (2020).
  7. A. Riva, et al., Minerva Cardioangiol. 67(1), 79–83 (2019).
  8. A. Riva, et al., Minerva Cardioangiol. (2018): doi: 10.23736/S0026- 4725.18.04795-3.

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