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Quercetin and rutin for allergy symptoms

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Natural Sources

Quercetin is a naturally occurring flavonoid found in red wine, grapefruit, onions, apples, black tea, and many other plants.  Quercetin is also known to have antioxidant and anti-inflammatory properties.

Sugar groups

Quercetin is an ‘aglycone’, which means there is not a sugar group attached.  The color is a brilliant yellow and is insoluble in water.  Quercetin can also have a sugar attached to it and called ‘quercetin glycone’.

 

Chemical Structure

  • Quercetin is 3,3’,4’,5,7 -pentahydroxyflavanone (or its synonym 3,3’,4’,5,7-pentahydroxy-2-phenylchromen-4-one).  Quercetin has an OH group attached at positions 3, 5, 7, 3’, and 4’.
  • Quercetin is an aglycone, which means there is not a sugar group attached.  The color is a brilliant yellow and is insoluble in water.
  • Quercetin can also have a sugar attached to it and called ‘quercetin glycone’.  Examples would include Rutin which gets converted to quercetin when metabolized in the body.

Here are more articles on quercetin including clinical trials.

 

Mechanism of Action

  • Anti-inflammatory – Quercetin inhibits the activity of inflammation producing enzymes including lipoxygenase and cyclooxygenase.  Inhibition of these enzymes prevents the formation of inflammatory chemicals from being producing including leukotrienes and prostaglandins.
  • Anti-histamine – Quercetin can prevent the release of histamine from immune cells that break down.  For example, when a mast cell or basal cell (i.e. immune cell) breaks down it will release histamine.  Histamine will contribute to symptoms of allergies (i.e. allergic rhinitis) including runny nose, itchy eyes, etc.
  • Mast cell stabilizer –   Quercetin can help stabilize mast cells to prevent them from breaking down.  Preventing the breakdown of immune cells will prevent the release of histamine.

Here are more articles on quercetin including clinical trials.

Here are more articles on quercetin including clinical trials.

Clinical Research

A search of PubMed using the keyword ‘quercetin’ with article types limited to Clinical trial will reveal 228 clinical trials.  These studies are a mixture of pure quercetin or quercetin found in natural products (e.g. onions).  There are several studies suggesting a benefit in immune response (1-2). However, no studies have been completed assessing it for reduction in allergy symptoms.

A criticism of quercetin is that it is considered to have poor bioavailability (i.e. absorption) as evidenced by low blood levels.  Strategies to increase blood levels of quercetin include taking it with dietary fat.(3)  However, it is important to point out that quercetin will be quickly metabolized to additional compounds (e.g. quercetin-glucuronide, etc.) that can also maintain activity (4).  These are often referred to as quercetin conjugates.  This type of conjugation occurs with many polyphenols including resveratrol.  Examples of these metabolites or conjugates include isorhamnetin-3-glucuronide, had the highest concentration at 3 months followed by quercetin-3-glucuronide, quercetin-3-sulphate and quercetin diglucuronide.

The time to reach maximum concentration of quercetin after oral dosing was: (5)

  • 50 mg will reach maximum concentration at 2 hrs
  • 100 mg will reach maximum concentrations at 3 hrs
  • 150 mg will reach maximum concentrations at 6 hrs

 

The maximum serum concentrations of quercetin after oral dosing was:

  • 50 mg will reach maximum concentration of 189 nanomolar
  • 100 mg will reach maximum concentrations at 295 nanomolar
  • 150 mg will reach maximum concentrations at 431 nanomolar

 

Rutin is converted to quercetin

Rutin when taken orally will get converted to quercetin once the sugar groups are removed (see figure) according to a human clinical trial.

Here are more articles on quercetin including clinical trials.

Dose

Dosing in clinical trials varies.  A popular dose used in dietary supplements of quercetin for allergy symptoms is 200 mg two times daily or 400 mg two times daily.  Daily doses usually range from 400 to 800 mg per day.

References:

  1. Quercetin supplementation and its effect on human monocyte gene expression profiles in vivo. Br J Nutr.2010 Aug;104(3):336-45.
  2. The acute effect of ingesting a quercetin-based supplement on exercise-induced inflammation and immune changes in runners. Int J Sport Nutr Exerc Metab.2011 Aug;21(4):338-46.
  3. Dietary fat increases quercetin bioavailability in overweight adults. Mol Nutr Food Res. 2013 May;57(5):896-905.
  4. Dose-response to 3 months of quercetin-containing supplements on metabolite and quercetin conjugate profile in adults. Br J Nutr.2013 Jun; 109(11):1923-33.
  5. Daily quercetin supplementation dose-dependently increases plasma quercetin concentrations in healthy humans. J Nutr.2008 Sep;138(9):1615-21.

 

Jeremy Johnson, PharmD, PhD
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Categories: Herbal Pharmacology