Written by Greg Arnold, DC, CSCS. Researchers found a 62% decrease in a marker of inflammation in a group given vitamin C and quercetin compared to placebo group.

Quercetin is one of the most abundant of a type of antioxidants, called flavonoids. It is present in a wide variety of fruits, vegetables, and berries (1) and shown to possess a number of healthful properties, most notably as an antioxidant and anti-inflammatory (2).  Now a new study (3) suggests that quercetin combined with vitamin C may improve both inflammation and cell damage levels.

In the study, 60 healthy men between the ages of 19 and 23 were given either 500 mg of quercetin, 250 mg of vitamin C, both quercetin and vitamin C, or placebo each day for 8 weeks.  Throughout the study, the subjects provided information on diet, physical activity, and any side effects.  The subjects also agreed to avoid the use of vitamin/mineral supplements, nutritional supplements, herbs, and drugs known to affect immune function for 3 weeks before and during the 8 weeks of study.

The researchers found that the greatest decreases in inflammation and cell damage occurred in the quercetin/vitamin C group.  Specifically, there was a 49% decrease in C-reactive protein levels (1.37 to 0.70 milligrams/Liter) compared a 35% decrease in the control group (1.47 to 0.97 mg/L) (p < 0.01).  No statistically significant decreases were seen in the quercetin-only and vitamin C-only groups.

There was also a 62% decrease in levels of another inflammatory protein called IL-6 (42.09 to 16.0 picograms/milliliter) compared to a 47% increase in the placebo group (50.5 to 74.13 pg/mL) (p < 0.01) with no statistically significant decreases in the quercetin-only and vitamin C-only group.  Unfortunately, the researchers did not offer any suggestions as to why the control group saw such a significant decrease in C-reactive protein.

Regarding cell damage, there was a 4.7% decrease in the quercetin/vitamin C group (73.15 to 69.75 pg/mL) of a measure of cell damage called F2-isoprostanes compared to no significant change in the placebo group (72.44 to 72.94 pg/mL) (p < 0.05) and the quercetin-only and vitamin C-only groups.

When suggesting why inflammation levels and cell damage levels were only statistically significant when quercetin was combined with vitamin C, researchers suggested research showing the ability of vitamin C to regenerate quercetin and maintain its’ antioxidant properties (4).  They went on to conclude that “ingestion of quercetin with vitamin C may improve its bioavailability probably though regeneration of oxidized form of quercetin” and suggest that “additional researches are requested” to further confirm their conclusion.

Source: Askari, Gholamreza, et al. “The effect of quercetin supplementation on selected markers of inflammation and oxidative stress.” Journal of Research in Medical Sciences 17.7 (2012).

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Posted August 14, 2013. 

Greg Arnold is a Chiropractic Physician practicing in Hauppauge, NY.  You can contact Dr. Arnold directly by emailing him at PitchingDoc@msn.com or visiting his web site at www.PitchingDoc.com

References:

  1. Harwood M. A critical review of the data related to the safety of quercetin and lack of evidence of in vivo toxicity, including lack of genotoxic/carcinogenic properties. Food and Chemical Toxicology 20087; 45: 2179–2205.
  2. Hamalainen M. Anti-inflammatory effects of flavonoids: Genistein, kaempferol, quercetin, and daidzein inhibit STAT-1 and NF-kappaB activations, whereas flavone, isorhamnetin, naringenin, and pelargonidin inhibit only NF-kappaB activation along with their inhibitory effect on iNOS expression and NO production in activated macrophages. Mediators of Inflammation 2007; 45673.
  3. Askari G.  The effect of quercetin supplementation on selected markers of inflammation and oxidative stress.  J Res Med Sci 2012; 17(7): 637-641.
  4. Skaper SD, Fabris M, Ferrari V, Dalle Carbonare M, Leon A. Quercetin protects cutaneous tissue-associated cell types including sensory neurons from oxidative stress induced by glutathione depletion: Cooperative effects of ascorbic acid. J Free Radic Biol Med 1997;22:669-78.