Monday, January 23, 2006

Green tea and health benefits

Michael, the Chinese medicine student who recently gave us insights in cha qi wrote to me:

"Despite recent Western research touting the health benefits of green tea, reliable Chinese medical sources (whom I trust completely) have suggested that because of certain properties (cooling, draining, etc.) green tea may not be beneficial for regular use for people over 35-40 years of age. My understanding is that it cools off the digestion, and can potentially clear too much heat from the body, damaging the yang energy—but this is only my understanding and I make no claims regarding accuracy/interpretation.

Anyway, for this reason, I only drink green or white (unoxidized) teas on rare occasion, and usually only when climatically appropriate (very hot days, of which we have relatively few in the Bay Area).

I’m emailing you about this because I’m curious re: whether this is something Teaparker has discussed. I’m assuming, of course, that he teaches about the seasonality of teas (Summer, Winter, etc.), but has he taught anything to your recollection regarding appropriate tea for different ages/periods of life?

Your photos of Mr. Wang, his age, and his affinity for highly roasted teas made me wonder about this. Mr. Wang’s longevity is certainly consistent with the information I have regarding the idea that more highly oxidized teas are more tonifying.

Any thoughts?"

My observation of tea drinkers in Taiwan confirms Michael's information about green tea: the older the person, the less green he likes his tea. Young tea drinkers are full of life and energy and can take some cooling, but older people who are more afraid of the cold prefer shou cha. My wife's grandfather (who died recently at 90 years of age) liked old roasted baozhong the best in his final years.

Teaparker told us that research has identified over 450 different chemical compounds in tea. The most important ones are the polyphenolic compounds. Green tea has twice as many polyphenols as Dong Ding oolong (250 ppm -parts per million- vs 137 ppm for the tea 'liquid'). Fermentation and baking/roasting are reducing the amount and changing the nature/effect of these compounds that are linked to the main health benefits. With so many compounds that are absorbed in small quantities, this is a very complex field that may be difficult to prove scientifically.

Teaparker didn't say anything about age, but he often mentions that the weather (and temperature) will have a big impact on which tea he chooses to drink: greener teas in summer and shou cha during cold winter days.

In its dry state, green tea has up to 30% polyphenols, the article said. They are benefitial is theory, but their cooling effect on the stomach may be detrimental. Roasted oolong should have only 10-15% polyphenols and therefore carry less benefits, but are easy on the stomach and warm your body. The best would be to have a tea with high polyphenols that is 'ripe' (shou) like roasted oolong. Do you know a tea that is first almost green and then transforms naturally into a ripe tea?

Aged raw pu erh is the correct answer! Pu er is associated with lots of health benefits and there must be a reason for it! I have seen recent results of chemical testings made by the tea research laboratory of the Yunnan Province on the 1990 wild raw Jiang Cheng brick: they show 35% to 39,98% tea polyphenols! This is even more than for green tea! There are several reasons for this high concentration of polyphenols:
- Pu er, in general, is a stronger tea that can be brewed twice as much as oolong,
- Slow aging is not transforming the chemical structure of pu er as strongly as for cooked pu erh.
- This brick is made of wild, first grade leaves that grow in nature and absorb more strength from their natural environment than plantation puer.

In conclusion, I agree with Michael that you have to weigh in the 'cool' nature of green tea (or light oxidized oolong) when you assess it's benefits on your health. It may actually do more harm then good if you feel 'cold' already. The very best in terms of health benefits (and in terms of taste) is wild aged pu-er: it's quite unique in that it combines a high concentration of tea polyphenols with ripe, warm tea characteristics.

5 comments:

R2K said...

mmm makes me want tea now :)

Rocketry

Yoann said...

Petite considération énergétique:
Le thé ayant une action diurétique, c'est à dire qu'il diminue l'énergie du rein, il a un action refroidissante. Le rein est en médecine chinoise l'organe de l'eau, de l'hiver, de la vieillesse, il a donc une influence sur la température du corps.
Le thé vert diminue donc cette énergie, les thés "chaud" (soit torréfiés, soit ayant accumulé la chaleur des ans) ont plutot tendance à réchauffer cette loge énergétique.
Ca c'est un raisonnement simple sur l'énergie du thé, mais il y a beaucoup d'autres facteurs à prendre en compte : les gouts et énergies de printemps, d'été ou d'automne des thés... Connnaitre le biotope d'origine de la plante et sa morphologie "normale" (sans taille, avec la floraison) serait indispensable pour résoudre des questions qui me trottent dans la tete....

gudipudi said...

can any one over here explain me the good causes in having tea....

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