Caffeine in Tea

There's a lot of information about tea floating around out there. Some sites on the internet may proclaim that tea cures Alzheimer's Disease, friends may go on about green tea's ability to make one grow younger, news articles may purport that tea extracts cured a lab rat's dental plaque. And for even experienced tea drinkers, determining what's bullshit and what's factual can be a chore.


Here's one of the most common factoids about tea.

Black tea, due to its oxidation, has the highest levels of caffeine of all tea types. Oolong teas have roughly 2/3 the caffeine of black tea, green teas have roughly 1/3, and white teas have even less than green tea. As a rule of thumb, the less processed a tea is, the less caffeine it will have.

Many tea drinkers take this to be a given. I know I did until recently. But in actuality, it's not true.

"All teas have roughly similar caffeine contents, and one cannot rely on the belief that green tea has less caffeine, as asserted by many popular claims. One such claim is that degree of fermentation governs caffeine content, with green having 1/3 and oolong having 2/3 the caffeine content of black tea. This has been debunked repeatedly."

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Basically, caffeine content is dictated by the genetic makeup of the tea plant. Some varieties have more caffeine than others, and also various other factors (such as which leaves are plucked, the season, fertilizer, etc.), but oxidation of the leaves does not contribute very much caffeine to the tea, which runs contrary to popular belief.

There is some truth to this myth, however. Green tea is typically brewed with fewer leaves than black tea, which means a cup of black tea will often have more caffeine than a cup of green tea (but not always).

What tipped me off was white tea. I've heard that white tea has very little caffeine and that it has almost as much as black tea. I did some research and found out that I'd been living a lie -- the green tea I often drink a few hours before bed was indeed what we keeping me up. And now I can't turn to white tea, because it apparently has caffeine levels similar to green tea, if not somewhat higher.

The good news is that tea still has much less caffeine than coffee, and that the caffeine in tea is less likely to give you the jitters. The caffeine is chemically the same as that in coffee, but the polyphenols in tea bind to the caffeine which results in not all of it being released into your system at once. Tea also contains L-theanine, an amino acid that calms and relieves stress.

So if you're particularly sensitive to caffeine, you may want to buy decaffeinated tea instead of substituting green or white tea for black and oolong tea.