A Look at the World’s Oldest Tea

Uncovering

Last week my family and I had the privilege to help a dear friend. Her mother’s apartment needed to be cleared out, and, sadly, she was a hoarder who hid her valuables. Treasure among the dross.

Or, was it all treasure to her?

This made me rethink my own possessions. Like a little box that I’ve kept since . . . well, forever.

Discovering

Opened, the box’s contents look like trash to someone who doesn’t attach a memory to the items. After all, who but me would know that the pencil stub had been sharpened with a knife by my  grandfather—whom I only dimly remember.

What would archaeologists of a distant future make of these trinkets? They wouldn’t know that when I looked at the pencil, I saw someone I cherished.

Yet—yet—they might well surmise that I held these trifles in some esteem, kept as they are, together in a box. Archaeologists do seek to attach meaning to what they uncover—while simultaneously striving to not make assumptions.

Taking Care with the Interpretations

This week, Guinness World Records validated that the tea leaves discovered in an emperor’s tomb in the Han Yangling Mausoleum in Xi’an, western China, are the world’s oldest (at least as of today!) at 2,100 years.

But this doesn’t mean simply that people—or at least the emperor—were drinking tea by then, nor is the age of the leaves necessarily the most important point of this discovery. Interpretations are always complex, and we must not apply today’s meaning to antiquity’s treasures.

Because tea does not grow near the area where the leaves were found, they were imported to Xi’an; because they were interred in Jing Emperor Liu Qi’s tomb, they obviously had significance. Researchers determined that the tea was high-quality beverage tea because it consisted mostly of buds of the species Camellia sinensis—but was it consumed as a beverage?

Although the researchers in this project say that their “study reveals that tea was drunk by Han Dynasty emperors as early as 2100 yr BP” (Lu et al. 2016), Professor James Benn, as quoted in NPR’s article on the discovery, cautions that the presence of tea leaves doesn’t mean that they were consumed as “tea” like we do today—they may have been part of a “medicinal soup,” for instance.

But as Professor John Speth of the University of Michigan points out, “there is evidence of much earlier humans boiling up plant-based concoctions as drinks. It probably wasn’t tea in the technical sense but the idea of brewing plant concoctions is many thousands of years older. It is likely in fact that Neanderthals were already doing it, judging by phytochemicals found in Neanderthal dental calculus (tartar)” (see also Hardy et al. 2012).

So C. sinensis may well have been consumed for millennia before tea leaves were interred in the emperor’s tomb; we just haven’t found physical evidence yet.

But their presence—coupled with the concomitant positive identification of tea leaves in Gurgyam Cemetery in Tibet—substantiates that tea was “being imported to Xi’an in the first century BCE, and westwards into Tibet by the second century CE” (Lu et al. 2016).

This is the earliest physical evidence that tea, along with other luxury materials, was being transported on the Silk Road between the two regions.

Before this discovery, we had believed that tea came to Tibet only when Tibetan king Songtsen Gambo married Princess Wencheng of the Tang Dynasty in 641, there being no evidence of tea on the Silk Road until the time of the Tang Dynasty. In addition, the oldest physical evidence of tea in the world had been from the Northern Song Dynasty in China, at the much later date of 960–1127.

The research team (Lu et al. 2016) writes that over 4,000 years ago, contact between eastern China, the Tibetan Plateau, and Central Asia resulted in “the spread of food grains, a few fruit trees and livestock, and can be connected with the development of settled farming in the Tibetan Plateau and parts of Central Asia.” Two thousand years later, luxury goods were being exchanged. And today, we have physical evidence that tea was among those goods.

So while the age of these tea leaves made the Guinness World Record, it is the leaves in context that make this a truly significant discovery.


Sources:
–Cherfas, J. “World’s oldest tea discovered in an ancient Chinese emperor’s tomb,” The Salt, NPR, January 26, 2016. www.npr.org/sections/thesalt/2016/01/26/464437173/worlds-oldest-tea-discovered-in-an-ancient-chinese-emperors-tomb.
–Hardy, K., et al. “Neanderthal medics? Evidence for food, cooking, and medicinal plants entrapped in dental calculus,” Naturwissenschaften 99(8):617–626. July 18, 2012.
–Lu, H., et al. “Earliest tea as evidence for one branch of the silk road across the Tibetan plateau,” Scientific Reports 6(18955). January 7, 2016.

–Swatman, R. “2,100 years old: Archaeologists discover world’s oldest tea leaves in China,” Guinness World Records, May 13, 2016. http://www.guinnessworldrecords.com/news/2016/5/archaeologists-discover-oldest-tea-leaves-in-china-after-2-100-years-428858.

Caffeine in Tea: How Much Is in Your Brew?

The first time I walked into TeaHaus in Ann Arbor, I was a bit staggered at the selection of loose leaf teas. Wow, this is terrific!—quickly followed by seriously?! how on earth do I pick?teawall

Because one of the great things about tea is that there are thousands of choices!  The downside? There are thousands of choices!

But let’s not stop there. Say that you want a tea from Camellia sinensis—as opposed to rooibos, fruit tea, or an herbal tisane—which narrows the field. However, you would prefer a brew that is on the lower end of the caffeine scale. Which is a valid preference. And, unfortunately, riddled with complexity.

Caffeine: It Doesn’t Act Alone

There are many many factors that determine just how much caffeine you will get in your cup of tea. . . . complicated by factors that affect how you will experience that caffeine.

A recently published study reiterated the finding that the relaxing effects of theanine (the amino acid found in tea) offset or blunt the stimulant effect of caffeine. Therefore, the theanine to caffeine ratio “determines the degree of stimulant effect of tea drinks. Moreover, together with caffeine, L-theanine has a synergistic positive effect on attention as demonstrated in human electroencephalography studies, and in a behavioral study” (Boros et al.).

So yes, caffeine is a stimulant and keeps us awake and alert whereas theanine relaxes us with those alpha brain waves (see my previous post). But caffeine coupled with theanine work together to promote attention (seems like a perfect marriage here!).

To complicate things even more, caffeine’s effects are also impacted by other xanthines such as theophylline and theobromine, and by polyphenols, which bind with caffeine, slowing its absorption.

So what we experience when we drink a cup of tea varies from tea to tea, and even varies from one cup to the next of the same tea!

Many Elements Impact How Much Caffeine Ends Up in Your Teacup

While keeping in mind that the levels of xanthines and polyphenols also vary with many of these same elements, the level of caffeine lurking in your brewed cup of tea is determined by:

  • type of tea plant: C. sinensis var. assamica (higher caffeine) or C. sinensis var. sinensis
  • whether the tea plant came from cloning (higher caffeine) or seedling
  • the age of the plant
  • stress of the plant (e.g., caused by pests)
  • soil conditions (higher nitrogen level means higher caffeine level)
  • climate
  • rainfall
  • growing season (the faster the plant grows, the more caffeine)
  • amount of shading the plant receives (more shading increases caffeine level—but shading also increases the theanine level)
  • which leaves are plucked (buds and young leaves have more caffeine)
  • how the leaves are processed after plucking (type of tea); for example, duration and temperature of withering, duration of oxidation
  • particle size: teabag (more caffeine due to the broken leaves) vs loose leaf tea
  • how the tea leaves are brewed, which includes:
    • temperature of water used
    • how much tea is used
    • method of brewing (e.g., loose, strained, teabag)
    • brewing time
    • which infusion it is
  • how much is consumed

Can You Do Anything about the Caffeine Level?

So is there any way to control the level of caffeine you are ingesting? You cannot “wash” caffeine out of tea­—nor would you want to remove caffeine in this way because caffeine and flavor go hand in hand. You would need to infuse a teabag, for example, for over five minutes to remove 80% of the caffeine—and clearly the second infusion would have no flavor left! And, other substances that contribute to flavor and health benefits (such as polyphenols) are also extracted quickly, another reason that we want to drink the first brew and not discard it.

With loose leaf tea, the flavor—and the caffeine—is maintained over multiple infusions, particularly with whole leaves. For those teas that have been shaped into pearls or rolled, each infusion will unfurl the leaves more fully, releasing additional caffeine. However, you can limit the amount of caffeine released by lowering your brewing temperature by 5° with each infusion. A bonus is that this also decreases bitterness in your brew (both caffeine and tannins are naturally bitter tasting, and both are released by hot water).

Your Best Bet?

Needless to say, endless research studies are delving into these matters­—all hoping to reduce the uncertainties and variables into a cohesive understanding so that we can more fully realize tea’s numerous health benefits. Meanwhile, both the FDA and the European Food Safety Authority cite 400 mg of caffeine per day as safe for adults.copper teacup

But again, how we experience that caffeine depends on so many things! Although caffeine is caffeine, when we drink coffee or caffeinated soft drinks or mate, the caffeine hits us quickly, unlike in tea, where the effects are mitigated. The upshot? Experiment. With different teas that you love, paying attention to how they affect you.

If even the smallest amount of caffeine is a problem, then move into the world of naturally caffeine-free fruit teas, rooibos, and honeybush. Many herbal tisanes are caffeine free as well. (Decaffeinated tea, however, does contain a small amount of caffeine.) There are so many outstanding choices!

In the world of tea, there really is something for everyone!


Sources:
–”Caffeine,” Science of Food and Cooking, http://www.edinformatics.com/math_science/science_of_cooking/caffeine.htm.
–”Caffeine and tea: Myth and reality,” by N. Melican,  February 6, 2008. http://chadao.blogspot.com/2008/02/caffeine-and-tea-myth-and-reality.html.
–”Chemical compounds in tea,” by T. Gebely, Tea Education. 2015. http://www.worldoftea.org/category/tea-education.
–”FDA to investigate added caffeine,” U.S. Food and Drug Administration. May 3, 2013. http://www.fda.gov/ForConsumers/ConsumerUpdates/ucm350570.htm.
–”Scientific opinion on the safety of caffeine,” EFSA Journal 13(5):4201. 2015.
–”Tea preparation and its influence on methylxanthine concentration,” by M. B. Hicks et al., Food Research International 29(3–4):325–330. 1996.
–”Theanine and caffeine content of infusions prepared from commercial tea samples,” by K. Boros et al., Pharmacognosy Magazine 12(45):75–79. January–March 2016.