how much is too much?

[tsusentei]

I have read a number of scholarly journals and articles on the chemical composition of tea, and I have never found anything like the information that is being discussed here. Does any one have the bibliographic information for these claims? I have an insatiable hunger for tea knowledge as much as tea. I do dislike the spreading unsubstantiated rumors, but would love to pass this stuff on if it is true. Sources?

[scruffmcgruff]

Which claims? There are several that have been discussed here. If you're talking about Proinsias' second-to-last post, read the second quote below. The first one is just some basic info on the chemical composition of tea that I thought might be interesting to some.

"Briefly, tea (Camelia sinensis L.) is particularly rich in polyphenols; they represent 30% of the leaf dry matter (18). Major polyphenols in the fresh tea leaves are flavanol monomers, among which (–)-epicatechin, (–)-epigallocatechin, and their gallic esters are particularly abundant. The so-called "fermentation" of black teas actually consists of enzymatic oxidation of native green tea polyphenols, catalyzed by polyphenoloxidase, followed by chemical reactions of the resulting quinones (18). A major part of tea leaf flavanols are thus converted into various types of products, including thearubigins and theaflavins, which are responsible for the characteristic dark brown color of black tea (20), and smaller quantities of theaflavic acids (21) and bisflavanols, which are also called theasinensins (22). The number of compounds is still increasing because new structures are regularly being identified (23–25), but no information is available on their respective concentrations in tea." (http://www.ajcn.org/cgi/content/full/81/1/223S)

"A second class of food tannins is the derived tannins (7). These complex compounds are formed primarily under oxidative enzymatic and atmospheric conditions during the manipulation of plants and subsequent processing into foods, e.g., oolong and black teas, red wines and coffee. Because of the complexity of the compounds of this class of tannins, strict chemical nomenclature has been difficult and often trivial names have been assigned as a consequence. Clifford (7) has proposed a series of naming rules for many dimers of derived tannins. Of importance to oolong and black teas are the flavanol-derived theaflavins. The unique feature of the theaflavins is the benztropolone ring, a seven-member ring, which is formed by the oxidation of the B ring of either (-)-epigallocatechin or (-)-epigallocatechin-3-gallate, loss of CO2 and simultaneous merger with the B ring of a second molecule of (-)-epicatechin or (-)-epicatechin-3-gallate (Fig. 2)... Thearubigins are also members of derived tannins (Table 2). [Emphasis added]"
(http://jn.nutrition.org/cgi/content/full/133/10/3248S)

This passage argues that tea contains "derived tannins." The specific compounds mentioned are well-documented as being present in tea, so the only revelation here is in the nomenclature. These are different from condensed tannins/ proanthocyanidins, which are apparently not found in tea but are found in fruits, red wine, nuts, and chocolate. The "tannins" commonly referred to as not being present in tea seems to be tannic acid.

So, Proinsias, it seems the person who replied to you on B&B may have been right. This is just one article, and I don't know how controversial it is, but it's something.

[Proinsias]

Cheers Scruff, another great debate solved with a conclusive; sort of, sometimes, well it depends on how you look at it answer.

[Salsero]

Cheers Scruff, another great debate solved with a conclusive; sort of, sometimes, well it depends on how you look at it answer.

I love closure!

Isn't the issue that people sometimes ascribe to tea a constituent of wine--tannic acid--that tea doesn't actually have? I've always thought that at the root of all these discussions was the analogy to wine.

[Proinsias]

I think so Salsero, but the substitution of 'tannic acid present in wine' for 'tannis' ended up with me looking a little silly and scruff possibly eating his foot and we can't have that can we?

[tsusentei]

Hey Scruff! Thanks, those are great articles!

I was also talking about the connection between the astringency in teas and a given compound. People talk about this all the time, but I haven't found anything conclusive on it. I don't get the whole wine and tea thing, I like both, rather alot actually, but they are really so very different.

[Proinsias]

I don't get the whole wine and tea thing, I like both, rather alot actually, but they are really so very different.

They do complement each other rather nicely, too much wine at night goes quite well with too much tea the next morning.

[eor1122]

Also I've been reading about tannins and from what I gather (I may be wrong) the darker teas have a higher concentration of tannins than the white/herbals and that tannins interfere with iron absorption.

I look forward to everyone's feed back.

Good news~
even with drinking lots of tea lately and continuing to take my daily iron supplement, not only was I able to donate blood on Saturday I was able to donate "double red" which requires a higher count than a single pint donation. I was so happy that my new love for tea hasn't effected my ability to donate


thank you everyone for all your information on my new love