Intestinal Flora And T4->T3 Conversion?

[Collden]

"[IMPROVING T4->T3 CONVERSION] If you were deficient in selenium, the correcting effect would be quick, but if there was a problem with intestinal flora, that would have to be taken care of before conversion was good. Other nutritional deficiencies could be involved. Daily raw carrot, weekly seafood and liver, enough sunlight and vitamin D, a good ratio of calcium to phosphate, are often helpful." - Ray Peat

Does anyone know more about this? What is the link between intestinal flora and T4->T3 conversion? I thought this was mostly done by the liver. Does serotonin or endotoxin interfere with the process?

 

[mrchibbs]

"[IMPROVING T4->T3 CONVERSION] If you were deficient in selenium, the correcting effect would be quick, but if there was a problem with intestinal flora, that would have to be taken care of before conversion was good. Other nutritional deficiencies could be involved. Daily raw carrot, weekly seafood and liver, enough sunlight and vitamin D, a good ratio of calcium to phosphate, are often helpful." - Ray Peat

Does anyone know more about this? What is the link between intestinal flora and T4->T3 conversion? I thought this was mostly done by the liver. Does serotonin or endotoxin interfere with the process?

Virtually any stressor interferes with the ability to convert T4 into T3.

And yes, intestinal bacteria is a big factor, because endotoxin needs to be detoxified by the liver, and therefore, it has less resources to do the conversion of T4 into T3. Similarly visceral fat creates a constant estrogen load on the liver, and reduces its ability to do other things. Which is why Ray emphasizes protein, and carrot salad. Mineral deficiencies also impair this process, because selenium, zinc, copper etc. are all needed for thyroid function. Emotional stress can cause the thyroid function to down regulate as well. Basically when people start taking thyroid sups they also need t0 start making large lifestyle interventions for it to work optimally.

The Influence Of Intestinal Bacteria Upon The Thyroid Gland (1923)

 

[JKX]

What Mr Chibbs said...

In addition SCFAs produced in the gut, especially acetate, are essential to allow T4 conversion to T3.

You can test this yourself by supplementing a little sodium acetate and watching what happens to temp and pulse.

I'm of the opinion that a bifidobacteria dominant colon is desirable. Good production of SCFAs and low lactic production.