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?

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.

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!

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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.