Anyone know? I've read very good things about quercetin supplementation. Does anybody know if it's safe to take it for moderate to long term?
ray told me he'd heard good things about quercetin from people
Really? I thought quercetin wasn't liked around here, because of its estrogenic and anti-thyroid effects.
Food Chem Toxicol. 2014 Apr;66:23-9. doi: 10.1016/j.fct.2014.01.016. Epub 2014 Jan 18.
The flavonoid quercetin inhibits thyroid-restricted genes expression and thyroid function.
Giuliani C1, Bucci I2, Di Santo S3, Rossi C4, Grassadonia A5, Piantelli M6, Monaco F7, Napolitano G8.
Author information
Abstract
Quercetin is the most abundant flavonoid present in a broad range of fruit and vegetables. Furthermore, quercetin is available as dietary supplements that are based on its antioxidant, antiproliferative and anti-inflammatory properties. However, concerns have been raised about the potential toxic effects of excessive intake of quercetin, and several studies have demonstrated that flavonoids, included quercetin, can interfere with thyroid function. In a previous report, we showed that quercetin inhibits thyroid-cell growth and iodide uptake. The latter effect was associated with down-regulation of sodium/iodide symporter gene expression. In the present study, we have evaluated the effects of quercetin on the expression of other thyroid-restricted genes, and we show that quercetin decreases the expression of the thyrotropin receptor, thyroid peroxidase and thyroglobulin genes. We further investigated the inhibitory effects of quercetin on thyroid function in vivo through evaluation of radioiodine uptake in the Sprague-Dawley rat, which was significantly decreased after 14 days of quercetin treatment. These data confirm that quercetin can act as a thyroid disruptor, and they suggest that caution is needed in its supplemental and therapeutic use.
Copyright © 2014 Elsevier Ltd. All rights reserved.
KEYWORDS:
Endocrine disruptor; FRTL-5; Quercetin; Radioiodide uptake; Rat; Thyroid
The flavonoid quercetin inhibits thyroid-restricted genes expression and thyroid function. - PubMed - NCBI
I've heard very good things about quercetin too, but stayed away from it because of the impression I've got from here.
Ray did say he’d heard good things about quercetin when I asked him. I almost have qualms about bringing it up Bc it’s not something I think he necessarily put a lot of thought into as an answer. He still recommended thyroid and vitamin d , the usual , and didn’t recommend quercetin or ketotifen but just said he’d heard good things. I think that maybe the estrogenic activity of phytoestrogens can sometimes be weak but the antithyrojd activiry would concern me more. But not a ton of good mast cell stabilizers out there