Comment · Sat, January 8, 2022 · ND Owner
Silymarin and Thyroid Disruption
Original post in this thread
Ratharax · 23 points
TLDR: Silymarin is comprised of chemicals that inhibit a transmembrane transporter of thyroid hormone into cells (MCT-8), as tested in vitro with murine (rodent) astrocytes (which are rather important for neuronal health!). Silichristin is by far the most potent inhibitor of this transporter. Healthy humans given 400 mg milk thistle extract had peak serum levels of silichristin sufficient for inhibitory action.
I was just looking into milk thistle extract, and from wikipedia found a study that shows that silymarin very strongly inhibits a transmembrane protein, MCT-8, responsible for transporting thyroid hormone into cells. Their study is on rodents, but they find that all of the flavonolignan components of silymarin, and by far most potently silichristin (a.k.a silychristin), inhibit MCT-8. They actually zeroed in on silymarin, and then silichristin, from a group of candidate chemicals because the inhibition is so potent
The authors state that most of the benefits that have been attributed to silymarin are focused on silibinin A & B, which are quite weak MCT-8 inhibitors, and so silichristin having such a profound effect has mostly been unnoticed, thus the potential harmfu…
What they were answering
Ratharax · 2 points
Awesome thanks so much!!
u/MisterYouAreSoDumb · ND Owner
So our current batch of normal milk thistle is right in line with that paper. The silychristin is at 16.79%. I read through the paper, and I think you are onto something. I am going to do more research and get a bunch more samples of milk thistle in to run through the lab. Very interesting find! Thanks for bringing it up. Maybe there is an opportunity here to create a new extract of milk thistle that focuses solely on silibinin A & B, and keeps the silychristin low. We might have to get creative to accomplish that, but we can certainly try!