Health Benefits of Tea - How These Effects Vary Between Different Types of Tea
Health Benefits of Tea - How TheseEffects Vary Between Different Types of Tea - Discussion of the health benefits and health
effects of tea has flooded the internet as well as print publications in recent
years. Commonly mentioned health benefits include antioxidant activity, cancer
prevention, lowering of cholesterol, lowering of blood pressure, reduction of
stress, antibacterial and antimicrobial activity, and enhancing general health
and promoting overall well-being.
Tea,
made from the leaves of the Camellia sinensis plant, has a long history of use
for health purposes. Tea originated thousands of years ago in ancient China as
medicine used to treat various illnesses; over hundreds of years, tea gradually
shifted first towards being viewed as a general tonic for good health, and then
developed into being viewed a beverage as it is today.
Varieties of Tea:
Tea
comes in many varieties, ranging from the least-processed white tea, to
unoxidized but generally steamed or pan-fired green teas, through intermediate
oolongs, fully-oxidized black teas, and aged pu-erhs.
Each
of these broad types comes in dozens if not hundreds of varieties, and within
each variety, individual teas vary greatly from one estate, farm, or factory to
another, and even from one year to the next (as they are influenced by variable
factors such as weather).
Different
teas can have remarkably different flavors, aromas, and other characteristics.
Not surprisingly, they have widely variable health benefits as well.
Are some varieties of tea healthier
than others?
Green
tea is widely touted as having a myriad of health benefits. Oolong tea (often
spelled wu-long in this context) is often pushed as a dieting or weight-loss
drink. Pu-erh tea is promoted as lowering cholesterol.
White
tea is often presented as having more antioxidants than other teas. Most of the
sources making these claims are companies promoting their own products; they do
not cite scientific studies backing their claims. While some of these claims
about health effects are true, others can be misleading or even outright wrong.
Which of these claims are true?
Some
of the most widespread and most misleading statements about tea are
generalizations about one broad class (such as green, black, or white) being
universally better than others are misleading. In reality, the health benefits
vary much more among individual teas than they do among broad categories.
Science firmly backs this perspective.
A
2005 article in the Journal of Food Science presented a study of the
distribution of Catechins and other chemicals in 77 different teas. Catechins
are the most well-known antioxidants in tea, and are well-established to have
positive effects on health. Most of the teas studied were ones widely available
in supermarkets in the U.S. The published study can be found here:
http://ddr.nal.usda.gov/handle/10113/1807
The
results are astounding: among black teas, the tea with the most Catechins had
over 12 times as much as the one with the least. Among green teas and others
(including white and oolong) the factor was even larger.
While
green teas tended to have more Catechins than black teas, a number of black
teas ranked higher than many of the green teas. Also, black tea contains theaflavins,
antioxidants not found in green tea except in tiny traces.
If we
accept these measures as a good indicator of health value, this study firmly
establishes that the health effects of tea must be addressed on the level of
individual teas, not broad categories.
So how do we maximize our health
benefits when drinking tea?
This
seems to present a problem. If we are seeking health benefits such as
antioxidants, and these benefits vary widely from one tea to the next, how are
we to choose what to drink? An obvious long-term solution is for scientists to
study and publish the antioxidant content of more teas, and also to continue
researching and questioning the validity of various claims of health benefits.
But
until this is done, the best we can do is to explore drinking a wide variety of
different teas...and perhaps more importantly, to be skeptical of bold claims
and sweeping generalizations that are made without reference to rigorous
scientific research.