Pu-erh tea, does it contain oxalate?

One of the intentionally aged teas, Pu-Erh has a loyal following.

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Re:

by kyarazen » Jul 22nd 14 1:17 pm

bonescwa wrote:Oxidation isn't required to form a kidney stone of calcium oxalate so i have no idea why an antioxidant would help when they already disparage theories where antioxidant effect makes sense
the kidney is pretty much an oxidative organ since oxidative deamination occurs all the time. perhaps antioxidants are nephro-protective in certain ways since tea polyphenols do pass through.

with regards to your previous post, in my POV its still an equilibrium thing. any form of calcium sequestration, even to the point of the events occuring in the kidney should have effects

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by bonescwa » Jul 22nd 14 3:36 pm

Calcium sequestration with big organic molecules isn't going to occur "in the kidney" which I assume you mean in the tubule of the nephron, large organic molecules would never pass into the tubule unless the person has a serious renal problem

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by kyarazen » Jul 22nd 14 4:11 pm

bonescwa wrote:Calcium sequestration with big organic molecules isn't going to occur "in the kidney" which I assume you mean in the tubule of the nephron, large organic molecules would never pass into the tubule unless the person has a serious renal problem
urinary polyphenols are intriguing biomarkers :)

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by bonescwa » Jul 22nd 14 6:14 pm

Hmm you're right. I hate renal physiology lol. But tea catechin or polyphenols being some kind of chelator for calcium is one thing, antioxidants somehow helping renal tubular cells to dissolve calcium oxalate crystals is another.

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Re:

by entropyembrace » Jul 22nd 14 6:28 pm

bonescwa wrote:Hmm you're right. I hate renal physiology lol. But tea catechin or polyphenols being some kind of chelator for calcium is one thing, antioxidants somehow helping renal tubular cells to dissolve calcium oxalate crystals is another.
http://ajcn.nutrition.org/content/79/5/727.full

Tea catechins are known to be absorbed by the intestine, conjugated by enzymes in the liver and kidney, and transported to various tissues in the body even including the brain :!: according to the review posted above.

So there is specific machinery in the body to utilize catechins from the diet :)

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Re: Pu-erh tea, does it contain oxalate?

by entropyembrace » Jul 22nd 14 6:32 pm

Balthazar wrote:
Rui wrote:Now I wish I could get hold of some of these papers that have been quoted but it seems they are all charged for. Therefore I am going to buy one or two for me to read probably the ones who are more directly related to Pu-erh.
If you know someone studying at a university there's a good chance the person will be able to help you get some (if not all) of these. Just saying, the academic publishing price model really is insane.
I agree the price to view individual papers is insane. I wouldn't pay for individual access if I didn't have access through my school's university. I think it's unfortunate that a lot of publicly funded research ends up behind paywalls :(

Still I post the links because I know there's other university students and people who work at universities here, and I have a hard time finding sources for tea chemistry on open access journals :(

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by bonescwa » Jul 22nd 14 6:33 pm

But what the hell is any cell going to do with this giant conjugated organic molecule? I don't know. This sounds so much like wishful thinking to me. It's like the powers that be want fish oil or tea or coenzyme q10 to be a good thing and overnight all these studies crop up saying it's good for everything from autism to celiac disease to kidney stones.

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Re:

by entropyembrace » Jul 22nd 14 7:17 pm

bonescwa wrote:But what the hell is any cell going to do with this giant conjugated organic molecule? I don't know. This sounds so much like wishful thinking to me. It's like the powers that be want fish oil or tea or coenzyme q10 to be a good thing and overnight all these studies crop up saying it's good for everything from autism to celiac disease to kidney stones.
Uhhh....there's lots of uses for giant conjugated organic molecules in general...some of them are vitamins, others hormones...ect... :shock:

And "the powers that be" don't get to write whatever they feel like and get it through peer review and into academic papers. There's real cell biology and physiology work behind this, and it didn't happen over night, there's at least 10 years of research.

As for what this specific big conjugated organic molecule does? I posted this earlier http://www.biomedcentral.com/1472-6882/13/228 it is open access so you can read it :)

It prevents mitochondria mediated apoptosis of proximal tubule epithelial cells

It alters the expression of superoxide dismutase, cytochrome c, osteopontin, and cleaved caspase 3

It increases urinary excretion of oxalate

Zhai etal. cites 4 other papers which support their conclusion that green tea catechin protects kidney epithelial cells from apoptosis triggered by the oxidative stress of excreting excess oxalate.

These researchers did real laboratory work with kidney cell cultures and kidneys in live lab animals to prove that the protective effects of green tea catechin are real, and worked the molecular mechanism of action. It's not wishful thinking, it's hard science.

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by bonescwa » Jul 22nd 14 7:35 pm

Well if it protects from apoptosis so much, maybe in 5 years they can implicate catechins in renal cell carcinoma. It's nothing personal, but in the current climate of publication races and quotas, there is so much faddish garbage out there it's not even funny

And I didn't mean vitamins, hormones etc so much as this foreign molecule from a plant having a discrete effect on cellular physiology. Looking at the Wikipedia article on catechins, it's looks like they do a little bit of everything? Hmm, so do I believe they actually do all that stuff, or maybe some new assistant professors needed publications?

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Re:

by entropyembrace » Jul 22nd 14 7:47 pm

bonescwa wrote:Well if it protects from apoptosis so much, maybe in 5 years they can implicate catechins in renal cell carcinoma. It's nothing personal, but in the current climate of publication races and quotas, there is so much faddish garbage out there it's not even funny

And I didn't mean vitamins, hormones etc so much as this foreign molecule from a plant having a discrete effect on cellular physiology. Looking at the Wikipedia article on catechins, it's looks like they do a little bit of everything? Hmm, so do I believe they actually do all that stuff, or maybe some new assistant professors needed publications?
"faddish garbage" usually doesn't take the form of real laboratory research that takes hard work with cell cultures and model organisms :wink:

Most vitamins are also foreign molecules from a plant...

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by bonescwa » Jul 23rd 14 12:07 am

http://link.springer.com/chapter/10.100 ... ltext.html

That basically summarizes my view of the scientific establishment as it stands today. I did a pub med search for catechins and apparently they cure liver cancer as well.

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Re:

by entropyembrace » Jul 23rd 14 12:27 am

bonescwa wrote:http://link.springer.com/chapter/10.100 ... ltext.html

That basically summarizes my view of the scientific establishment as it stands today. I did a pub med search for catechins and apparently they cure liver cancer as well.
Each claim needs to be assessed individually. You're discrediting a very specific statement with a broad brush based on a general distrust of publication standards. Instead of saying there are problems with the scientific publication process so you won't believe anything that's published why not look at the specific statement and papers and evaluate their credibility based on their own merits?

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Re: Pu-erh tea, does it contain oxalate?

by bonescwa » Jul 23rd 14 1:02 am

entropyembrace wrote:
bonescwa wrote:http://link.springer.com/chapter/10.100 ... ltext.html

That basically summarizes my view of the scientific establishment as it stands today. I did a pub med search for catechins and apparently they cure liver cancer as well.
Each claim needs to be assessed individually. You're discrediting a very specific statement with a broad brush based on a general distrust of publication standards. Instead of saying there are problems with the scientific publication process so you won't believe anything that's published why not look at the specific statement and papers and evaluate their credibility based on their own merits?
Because I don't have the lab equipment or time to do so. After you have seen so many health crazes come on go, I think you'll be a bit sympathetic to my sentiments. They used to be only in the popular press, but now academia latches on to the next big thing and obsesses over it for a while until they get tired of it and move on to something else. These little effects they find in cell cultures and lab animals, I'm not saying they are totally fabricated or grossly exagerrated, but they rarely if ever translate into a meaningful effect in clinical trials. It's almost to the point where I'd believe pretty much anything they squirt onto a renal cell culture will show evidence of slight inhibition of some minor step along the long apoptosis cascade, if they apply the right statistical tricks.

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by bonescwa » Jul 23rd 14 1:07 am

And I totally get it, I have no room to talk at all, I didn't even read the paper! But my skepticism meter goes off when I can search catechins in pubmed or Googlescholar and it sounds like the proverbial snake oil cure for everything under the sun. One article said it prevents apoptosis of renal cells, two more say it is pro-apoptotic for hepatocellular carcinoma cells.

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Re: Pu-erh tea, does it contain oxalate?

by entropyembrace » Jul 23rd 14 1:24 am

bonescwa wrote: It's almost to the point where I'd believe pretty much anything they squirt onto a renal cell culture will show evidence of slight inhibition of some minor step along the long apoptosis cascade, if they apply the right statistical tricks.
Reading an open access paper doesn't require lab equipment or very much time. Care to point out the statistical tricks they used?

The results weren't slight either...

Besides that I don't think when doctors have been routinely telling kidney stone patients for years that they can drink green tea it's a health fad?