Quercetin and C-Reactive Protein (CRP)

I recently read a study with a very long title, The anti-inflammatory flavones quercetin and kaempferol cause inhibition of inducible nitric oxide synthase, cyclooxygenase-2 and reactive C-protein, and down-regulation of the nuclear factor kappaB pathway in Chang Liver cells (!), published in the “European Journal of Pharmacology” in February of 2007. The abstract can be seen here: http://tinyurl.com/26yy5q I was able to read the full study thanks to a friend (grazie, Sherlock!). As usual, I would be more than happy to forward the study upon request.

First, what are Chang liver cells? The online Dictionary of Cell and Molecular Biology tells us that these liver cells are derived from non-malignant human tissue. Now, I don’t want to get involved in a detailed explanation concerning inducible nitric oxide synthase, or iNOS, which is beyond my purpose here, anyway (phew!!!). Let it suffice to say that iNOS is linked to inflammation, and anything that inhibits it is good news. We already know about COX-2 (see my “Ellagic Acid” and “Natural COX-2 Inhibitors” Pages for more info) and CRP, and of course the ubiquitous NF-kappaB. Ah yes, and kaempferol is a natural flavonoid found in tea, broccoli, grapefruit and other plant sources. On with the study, then.

On page 222 we read that Reactive C-protein (CRP) is an acute phase protein produced by hepatocytes whose serum elevation is considered as indicator of chronic inflammation and whose interaction with endothelial cells may be the mechanistic link between CRP and atherosclerosis [ ]. It is known that IL-6 induces CRP through a mechanism involving NF-κB [ ], but no study has until now documented potential effects of flavonoids on CRP expression in liver cells. Hepatocytes, by the way, are liver cells (for the more scientifically-minded, epithelial cells found in the liver that, among other things, have the function of helping to detoxify our blood).

Both quercetin and kaempferol reduce iNOS and COX-2: The present study indicates that both flavones reduce iNOS protein level in activated Chang Liver cells and that kaempferol was a slightly more potent inhibitor at low concentrations. COX-2 protein level was also reduced [ ] And, most importantly for our purpose, i.e., identifying substances that reduce CRP levels naturally: Our data show that both quercetin and kaempferol significantly reduce CRP protein level in liver cells and that this inhibition is concentration-dependent [ ]. SIGNIFICANTLY REDUCE? Well, I have been putting quercetin powder in my curcumin/chocolate mixture for other reasons (see my Bioavailability page for more information), but I am very pleased to discover that it may also be reducing my CRP levels.

The study ends: In summary, the present study indicates that the modulation of iNOS, COX-2 and CRP by quercetin or kaempferol may contribute to the anti-inflammatory effects of these two structurally similar flavonoids in the liver, via mechanisms likely to involve blockade of NF-κB activation. Sounds good to me!

Important aside. After reading this study, I must post a warning: at very high doses, quercetin MAY have some genotoxic effects, see http://tinyurl.com/2lzaw6. The words to keep in mind are may and very high doses. Low doses of quercetin are okay, and I have confirmed this elsewhere (see for instance: http://tinyurl.com/2uvbzt). I have been taking a maximum of two grams per day. Not much, so I am not in the least concerned and will continue to take my daily dose, but it reminds me that caution is the name of the game, as the saying goes. So, do your research…first!

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