Hello i've recently posted about my subclinical hypothyroidism results and i'm having some confirmatory tests next week. I've been looking at my supplement regime and i've been taking Quercetin with Bromelain regularly for about the last 15 years only 500mg a day. There have been a few papers recently linking Quercetin to Thyroid issues mainly experimenting on rats. Has anybody had any experience with Quercetin? I had some neuromuscular issues a long time ago and it really helps but i'm thinking i may have to stop taking it but i don't know if its the cause or whether i'm just overthinking it. I stopped taking it for 6 weeks before i did the second blood test and my TSH was roughly the same so i'm thinking its probably not the issue but may be best to stop anyway. Just wondering if anyone knows of a replacement for it? Cheers.
Hypothyroidism and Quercetin: Hello i've recently... - Thyroid UK
Hypothyroidism and Quercetin
The flavonoid quercetin inhibits thyroid-restricted genes expression and thyroid function pubmed.ncbi.nlm.nih.gov/244...
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,...
pubmed.ncbi.nlm.nih.gov/244...
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Unless you've also been eating excessive amounts of fruit and vegetables every day, I doubt the dose you've been taking is the cause of your thyroid issue. But, everyone is different and what may not be excessive for one person, may be for another.
I seem to recall bromelain is supposed to stimulate the thyroid. That makes me wonder whether the bromelain in your supplement could be counteracting the negative affect of the quercetin.
Thanks for this. I've started taking Quercetin for my illnesses didn't stop to think about thyroid function. Maybe fisetin is a possible alternative.
On the other hand, you could have already been hypo 15 years ago, and that was the cause of your neuromuscular issues. Hypothyroidism affects every part of the body.
Thank you yes I have thought about that. I thought the Quercetin may have helped because it’s a potent anti inflammatory and may have kept the thyroid inflammation to a minimum but it’s so difficult to tell. I’ll probably never know now if I start taking levothyroxine in a few weeks.
Also worth thinking about is the effect of Quercetin on iron levels. If, like me, you struggle with raising ferritin levels be aware of this. I’ve stopped taking it for a while so I can try and get my iron levels up.
Hi ockerdoc,
I'd suggest comparing your FT4 and FT3 before and after as well, as those will provide a more accurate measure of any changes in your thyroid functioning than TSH alone.
I was just talking about this topic earlier today as I've been blown away by the difference that I think quercetin may have made for me (though I've been using it specifically for allergies vs inflammation or neuromuscular issues).
I've never taken a quercetin supplement out of an abundance of caution due to its potential negative effects on thyroid functioning and iron levels, both of which I struggle with. However, this past winter started adding more dietary amounts of quercetin to my diet almost daily (primarily via capers, at about 10 g a day which is maybe a teaspoonish, in addition to the red onions apples etc already in my diet) and for the first time in 15 years, I am thus far this spring not having the extreme digestive allergy issues that usually come on for me each March/April, despite greater than normal pollen counts in my area 🤞.
I can't say for sure it's the dietary quercetin that has helped, as I'm also on new thyroid meds and have started supplementing with Zinc more regularly and am probably getting more vitamin C than previous years etc. But, in almost all other ways in terms of thyroid symptoms I've felt worse, so my bet is on the potency of dietary quercetin perhaps combined with Vit C and other nutrients. (Vit C and quercetin, along with bromelain, are known to work synergistically).
Capers are among the most concentrated food sources of quercetin (the estimates I've come across for their content is about 18-50mg of quercetin per each 10 g of capers, though not sure if that applies to marinated capers) and I feel safer with those amounts than the high doses in supplements. I also prefer to get my nutrients through diet, So, that's an alternative you could try if inclined.
Thank you yes I’ve gone back and checked my levels again. It’s interesting because while taking quercetin my Free T4 was 16.7 (12-22) after stopping fir 8 weeks it had gone down to 13.5. Free T3 was 4.8 (3.1-6.8) while taking quercetin then 4.5 after stopping so a bit lower but probably not statistically significant. TSH was 4.2 while taking quercetin and then 4.68 after stopping. I was trying to find out some more information last night and apparently one scientist has said that the dihydrate form of quercetin is safe to take for people with thyroid issues. Looking at my numbers I wonder whether taking quercetin all these years has actually suppessed my hypothyroidism somewhat due the anti-inflammatory effects of the quercetin. I’ve gone back to taking it again now as I do feel better when I’m on it. You read these papers and panic but what happens in rats doesn’t always happen the same way in humans especially at the relatively low levels that we supplement with.
Hi ockerdoc sorry for the delayed reply. This is really good to know - I def would not have imagined your numbers would be better on quercetin than off! I wonder how much of a role the bromelain is playing?
In either case, between those numbers and the fact that you feel better on the supplement it certainly doesn’t seem to be causing a problem.
Thanks for sharing the results of your experiment. If at anytime I’m having trouble getting enough through diet (or I get sick of eating capers daily 🙂) I’ll consider a trying a quercetin + bromelain supplement myself based on this. Can I ask what brand you take?
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