Tea and Caffeine, Explained

ABSTRACT:
All true tea (of the genus Camellia) contains caffeine
Tisanes (non-tea plants) contain no caffeine (exceptions include yaupon, yerba mate, cascara, and others).
Oxidation level—what determines if a tea is white, green, oolong, black, etc.—does not affect caffeine content.
Some production methods
(like roasting) can lower caffeine content.
Tea weight, water temperature, and steep time will affect how much caffeine is extracted.
An average cup of tea (3 grams steeped for 3 minutes in 350 ml water) contains 60(ish) mg of caffeine.

THE GIST

"Tea comforts the spirit, banishes passivity, lightens the body, and adds sparkle to the eyes."⁣
- Shen Nong,Medicinal Herbs

Probably what ol’ Shen was experiencing when he wrote this thousands of years ago were the stimulating effects of caffeine (coupled with the entourage effect of other psychotropic cofactors in ancient tea trees…maybe. No way to know, and we don’t deal in folklore or speculation.) 
So let’s stick to the facts:

Tea—that is, a liquid extraction of the botanical constituents in dried tea plant, genus Camellia—contains caffeine. No two ways about it, really. Unless your tea is pressure cooked with carbon monoxide (how “decaf” is made) or thoroughly roasted (eg houjicha), it has caffeine. About half a cup of coffee’s worth, in fact. And while the chemical makeup of each tea is unique, caffeine is a relative constant.

Tisanes—or, liquid extractions of non-tea plants, like herbs and flowers—contain no caffeine. Well, some do; yaupon, yerba mate, guayasa, guarana, cascara, and the list probably goes on. But in general, non-tea plants have no caffeine. They may stimulate (Ever tried aged white ginseng? 🤪), but not in the coffee-jitters sense.

This caffeine conversation is one reason we do battle against that resilient misnomer: “herbal tea”.  Why? Because it’s just plain inaccurate. Tea leaves blended with non-tea plants could rightly be called “herbal tea”, but that would confuse the rest of us who think of peppermint and chamomile as herbal tea. The French tisane‎ is a more correct and useful word. And it’s important to know if you’re drinking true tea, as it has health implications.

What implications? Well, we know caffeine gets us wired. But why—and why does the tea plant have it at all?

PHARMACOLOGY

It’s a defense mechanism! Caffeine is a powerful insecticide, and the tea plant evolved over countless millennia to favor synthesizing it for its own protection.

Also known as “theine” (not to be confused with l-theanine, which we’ll get to later) in the context of tea, caffeine is an alkaloid compound of the methylxanthine class, formula C8H10N4O2.
Here we have its molecular structure:

Now write that down. Got it? No? Well, for this little rundown on caffeine in tea, it’s not super relevant. All you really need to know is that caffeine is a central nervous system stimulant, and tea has it. It also has countless chemical co-factors like l-theanine (abundant in matcha) that synergize with theine. In the case of l-theanine, the compound counteracts caffeine’s vasoconstricting (i.e. blood pressure raising) effects, promoting feelings of calm along with the alertness caffeine provides. We don’t talk much about tea’s health effects, purported, factual or otherwise, but this is science, and we trust the lab coats at this tea company.

(Fun fact: technically, caffeine is toxic to humans. Luckily, our oversized livers metabolize the minuscule amount found in tea plants effectively. That we’re able to enjoy tea’s mild stimulant effect is a happy accident of biology.)

One of the great misconceptions in tea is that different types contain different amounts of caffeine.
Here's a handy chart that breaks it all down:

Mind blowing, right? It's true. Steeping parameters—that's tea weight, water temperature, and steep time—are what make most of the difference in extracted caffeine content.

There are other persistent myths about tea. Let's dispel those, too:

MYTHS

- Green tea has more caffeine than black tea.Nope. See chart above.

- White tea has the most caffeine.The chart!

(Really, any version of the sentence “____ tea has more/less caffeine than ____ tea” is probably false. It all depends on leaf weight, water temperature, extraction time, and the unique biology of different tea plants.)

- Tea caffeine is different than coffee caffeine.Sort of. Theine (the term for caffeine found in tea, you recall) and coffee caffeine are exactly the same, but tea’s many additional cofactors change the way you perceive caffeine’s effects.

- Gushu / laocong / old tree tea contains more caffeine. This one’s for the teaheads out there. The answer: probably not. There’s a popular theory about the effects of drinking tea from older trees, namely that they can get you “tea drunk”. This state is often described as a feeling of pleasant airiness and joviality, and is said to be the result of a tea’s cha qi or “tea energy”. The idea is that older tea trees—some verifiably several hundred years old—have deep reaching roots able to extract more nutrients from the soil, and that the terroirs these trees are normally found in are naturally biodiverse with rich soils, enhancing the effect. The logic tracks. Still, there is no hard evidence to substantiate this. All we have is hearsay. But ask any pu’er lover and they’ll swear it’s a thing. Time to run some experiments with our old tree tea cakes, eh?

IN SUM

- All teas have similar caffeine content.

- (Most) non-tea plants don’t.

- Tea type is mostly irrelevant to caffeine content.

- Processing steps—decaffination, high heat roasting—can remove a tea’s caffeine.

- The caffeine in your cup has much more to do with how much tea was steeped, in what temperature water, and for how much time.

If you’re looking for a serious buzz, seek out teas from healthy tea trees, processed without high heat, and that are verifiably from older trees. The best way to find all this out is to ask your vendor; if they’re any good, they’ll be fully transparent with these details. 

Now you know! And with any luck, our inbox will chill out about caffeine. Fingers crossed!
(Just kidding—your questions are always warmly received.)