Posting this here as not sure where as, but some good info on how vitamin A reduces NADPH and glutathione. Those of us you took accutane, it is imperative that we deplete it from our bodies, either very long water fast or zero vitamin A diet. I am now close to 4 months zero vitamin A and it is doing great things. Viewing vitamin A as a un-essentiall and pretty much a toxin is looking more and more real. So if you have PFS and continue to eat or use TEI supps with vitamin A (palmitate - ParaPack), I think you will have trouble progressing. Also roundup(Glyphosate) is in the food chain bigtime, and it blocks the breakdown of vitamin A, and seems to decrease glutathione as well.
Taken from a guest post on Genereaux's blog
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https://www.ncbi.nlm.nih.gov/pmc/articles/PMC1217027/pdf/8660285.pdf
Retinoic acid modulation of glutathione and cysteine metabolism in chondrocytes(Cartilage)
“Secondly, we found that intracellular glutathione levels are
regulated by retinoic acid. Thus, in the presence of
physiological concentrations of the retinoid, there is a
profound decrease in both glutathione and cysteine levels. It is probable that the concomitant decrease in both cellular and extracellular cysteine concentrations results from the change in intracellular glutathione metabolism.”
(JF: well, duh, - the body uses Cysteine to make Glutathione, so they might want to beef-up that "probable" to a "most likely" and still leave room to be wrong. Let's see; deplete Glutathione with Retinoic Acid, check, put the cells/tissue in a panic to create more, check, the local Retinoic Acid inspired emergency grabs every scrap of Cysteine it can find, check, but where's the Glutathione we might assume the Cysteine was used to make? Is this another one of those - "We may have taken such a short-term look at the situation, that our snapshot doesn't actually represent what's going on, but we're confident we'll eventually get to the bottom of it all"? Did they give the Cysteine a chance to become Glutathione? How did they both disappear? What did they disappear into? Is this some kind of Retinoic Acid-as-Conan scenario, broadsword slicing everything to bits? Remember that paper from 2018 that said if researchers had extended the time-parameters of the studies they performed (it was a review paper), that they might find out Retinoic Acid was the cause of all of the Autoimmune Diseases? I wonder if that review group is still working somewhere? Siberia, perhaps? How’d that line even get past the editorial board? Oh, I forgot already, peer-review takes 4 years.)
(JF: I guess you could say “regulated” (above), but the word doesn’t have the same meaning that most of us are walking around with. It's like saying, “The life of the test animal is regulated by Arsenic”. Then they throw a few more variables into the mix and end with a conclusionary kludge. I wonder what the meaning of "modulating" is to these folks. Could it eventually come to light that "modulating" actually means the body creates Glutathione to protect itself from mad-scientists running around, killing and torturing rodents by the millions, with beakers full of Retinoic Acid in their hands?)
“Finally, we explored the effect of medium components on chondrocyte thiol status. We noted that while
ascorbate alone did not change cell thiol levels, (JF: presumably in the cells) it did cause a 4-fold decrease in the extracellular cysteine concentration (JF: that’s interesting for sure). When retinoic acid and ascorbic acid were
both present in the medium, there was a marked decrease in the level of glutathione. In contrast, the
phosphate concentration of the culture medium served as a
powerful modulator of both glutathione and cysteine.
(JF: is "modulator" the same as "regulator"?)
Results of the study clearly showed that there is a
profound decrease in intracellular levels of both cysteine and glutathione
(JF: due to Retinoic Acid) and that thiol levels are
responsive to ascorbic acid and the medium phosphate concentration. These findings point to a critical role for thiols in modulating events linked to chondrocyte maturation and cartilage matrix synthesis and mineralization.”
Thirdly, we noted that
caudal chondrocytes contain half as much glutathione as do the cephalic cells and
the level of the thiol is not influenced by retinoic acid. The profound differences in thiol metabolism between cephalic and caudal chondrocytes
suggest that the retinoid effects are cell specific, possibly related to the acquisition of receptors by cephalic cells.
(JF: now that one looks like a clue. Cell specific retinoic acid effects. Hmmm)
Considering the
control of cellular thiol levels, the investigation
clearly showed that the retinoid [retinoic acid] caused a
dose-dependent decrease in the
intracellular concentrations of
glutathione and
cysteine.
(JF: now we have three words; “regulates”, “modulates”, and “controls”).
Retinoic acid inhibits anaerobic energy metabolism; accordingly, a reduction in glycolysis would limit pentose phosphate shunt activity and lead to a drop in the level of NADPH, a required co-enzyme for glutathione synthesis.
Environ Toxicol Pharmacol. 2007
Cysteine turnover in human cell lines is influenced by glyphosate.
Pesticides are widely spread in the environment and there is a lack of knowledge concerning the impact of these substances on the human cell. In the present study the effect of low doses of the pesticides bentazon, metalaxyl and glyphosate on the
cellular metabolism of glutathione and cysteine was examined in HeLa and hepatoma cell cultures. No effect was observed when the cells were exposed to bentazon or metalaxyl. However,
significant changes in the intra- and extracellular concentration of cysteine, a precursor for glutathione synthesis, were detected when glyphosate was added to the medium. This finding was observed in the presence of
micromolar concentration range of glyphosate, and is
relevant when compared to concentrations observed in monitoring programmes.
From Wiki on Cysteine
Precursor to the antioxidant glutathione[edit]
Due to the ability of thiols to undergo redox reactions,
cysteine has antioxidant properties. Its antioxidant properties are
typically expressed in the tripeptide glutathione, which occurs in humans and other organisms. The systemic availability of oral glutathione (GSH) is negligible; so it must be biosynthesized from its constituent amino acids,
cysteine, glycine, and glutamic acid. While glutamic acid is usually sufficient because amino acid nitrogen is recycled through glutamate as an intermediary,
dietary cysteine and glycine supplementation can improve synthesis of glutathione[15].
(JF: that’s pretty much what I’m looking for, even as I lob the blue-collar razz at these researchers. (Hey, most of it is our tax dollars anyway, we want our money's worth, eh?) If we know that Retinoic Acid is the main problem in Retinoid Toxicity, and we know that it depletes Glutathione in cells, and that dietary Cysteine and Glycine can help us make Glutathione, then what’s not to like about that? These amino acids may not be direct counters to Retinoic Acid, but they sound like they can be very helpful in a protection sense at the very least, and at levels (cells, organs and tissues) in which we might not perceive the beneficial effects right away. In fact, some things we probably can’t perceive until significant damage is done and pain or something else sneaks up on us. I still think there could be a more direct effect in play, so I’ll keep looking at that angle. The paper about Glycine versus Necrosis is enough to make me think there’s more to it than just a powerful antioxidant effect. There's so much information out there about Glycine, Taurine, Cysteine, and their part in transmembrane proteins (among other things) that it wouldn't surprise me to find something simple in the studies that medical science has ignored for years.)