Vitafoods Asia 2019



25-26 September 2019  




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Quercetin, a natural antihistamine

Quercetin molecule.

Quercetin is a plant-based active that helps preventing allergies such as allergic rhinitis. It is used by bioXtract in its patented natural antihistamine, Nasaler®.


Where is Quercetin found ?

Quercetin is one of several naturally occurring dietary flavonol compounds belonging to a broad group of polyphenolic flavonoid substances.


Fruits and vegetables, particularly apples, cranberries, blueberries, and onions, are the primary sources of naturally occurring dietary quercetin of the typical Western diet and contain the flavonol at levels as high as ~350 ppm. Black tea, as well as red wine and various fruit juices, are also identified as rich dietary sources of quercetin [1].


Anti-oxidant, anti-carcinogenic, anti-inflammatory, and cardioprotective properties are several key biological functions ascribed to quercetin.


Antihistaminic properties

Quercetin is considered as a natural antihistaminic. But quercetin has a larger spectrum of action than classical antihistaminics [2][3][4]:


  • It prevents the recruitment of mast cells (inhibition of chemokines (IL-8, ICAM-1) and cytokines),


  • It stabilizes the mast cells and blocks its degranulation. By this way, the granule components (histamine, proteases, serotonin…) are not released and do not lead to symptomatic allergic effects.


Quercetin anti histaminic properties.


Quercetin blocks the recruitment, the activation and the degranulation of mast cells. Mast cells can be considered as the “hub” of allergic rhinitis. Quercetin can stabilize it in an “inactive state” and in this way, prevents symptoms of allergic rhinitis. Quercetin, represents a new generation of antihistamine with a broad spectrum of action.


Quercetin also acts in the early stages of the allergic reaction, avoiding the activation of the mastocytes, by downregulating the balance Th2/Th1 in favor of the specific immune defense reaction Th1 instead of allergic reaction Th2. By decreasing the Th2 response, Ig-E production is inhibited and consequently, mastocyte activation [5].


Quercetin prevents symptoms of allergic rhinitis.


Scientists agree that quercetin has in vitro antiallergic effects on human cells. However the challenge with quercetin is to get the same effect in vivo in humans. In fact, due to the low solubility and low bioavailability of quercetin, active plasma concentrations are not easy to reach.


[1] Harwood M, Danielewska-Nikiel B, Borzelleca JF, Flamm GW, Williams GM, Lines TC. A critical review of the data related to the safety of quercetin and lack of evidence of in vivo toxicity, including lack of genotoxic/cacrinogenic properties. Food Chem. Toxicol. 2007; 45: 2179-2205.


[2] Kempuraj D, Madhappan B, Christodoulou S, Boucher W, Cao J, Papadopoulou N, Cetrulo CL, Theoharides TC. Flavonols inhibit proinflammatory mediator release, intracellular calcium ion levels and protein kinase C theta phosphorylation in human mast cells. Br. J. Pharmacol. 2005; 145: 934-944.


[3] Min YD, Choi CH, Bark H, Son HY, Park HH, Lee S, Park JW, Park EK, Shin HI, Kim SH. Quercetin inhibits expression of inflammatory cytokines through attenuation of NF-kappaB and p38 MAPK in HMC-1 human mast cell line. Inflamm. Res. 2007; 56: 210-215.


[4] Kempuraj D, Castellani ML, Petrarca C, Frydas S, Conti P, Theoharides TC, Vecchiet J. Inhibitory effect of quercetin on tryptase and interleukin-6 release, and histidine decarboxylase mRNA transcription by human mast cell-1 cell line. Clin. Exp. Med. 2006; 6: 150-156.


[5] Nair MP, Kandaswami C, Mahajan S, Chadha KC, Chawda R, Nair H, Kumar N, Nair RE, Schwartz SA. The flavonoid, quercetin, differentially regulates Th-1 (IFNgamma) and Th-2 (IL4) cytokine gene expression by normal peripheral blood mononuclear cells. Biochim. Biophys. Acta. 2002; 1593 : 29-36.