Caffeine in Tea

by Jake Mardell

Caffeine is without doubt the most widely consumed psychoactive drug on earth. Right this moment, it is coursing through my veins, and I am by no means alone in this regular drug habit. Coffee drinkers, chocolate bar eaters, paracetamol poppers, and of course the esteemed tea drinker, all consume caffeine on a daily basis.

Numerous studies show that caffeine boosts metabolism, elevates mood, increases athletic performance and enhances cognitive function. But numerous studies also show that caffeine causes anxiety, decreases cognitive function, leads to dependence, insomnia, and even incontinence.

Health advice seems to change with the waxing and waning of the moon. One moment, green tea is the poster child of the mindfulness set, the next, an edict from the health professionals has it banned, along with all other caffeinated beverages.

Myths and pseudo-science abound, so in order to understand caffeine in tea a little better, let’s clear up some of the more common misunderstandings.

Tea vs. Coffee

The caffeine in tea vs. caffeine in coffee debate is well-trodden ground. Conventional wisdom seems to suggest that coffee is a more highly caffeinated beverage than tea. Conventional wisdom is largely correct.  The surprising, and therefore popular fact, that tea contains more caffeine than coffee seems to arise from some truth. In their pre-brewed form, tea leaves do tend to have a higher caffeine content than coffee beans. So, if you are eating the product straight, the urban myth holds. But in its drinkable form, tea tends to have a much lower caffeine content, more of it being left behind in the leaf post-brew. 

Green vs. Black 

It is commonly thought that green and white teas contain less caffeine than other types of tea. That stronger flavoured black teas have a higher caffeine content seems to make sense. But a 2005 study published in the Journal of Food Science actually found that the most caffeinated of 77 teas it surveyed, was a white tea [1].  

The cultivar matters a lot more than the general type of tea, but so too does the part of the plant used. Tips and younger leaves contain more caffeine than older parts of the plant, presumably because caffeine acts as a natural insecticide, protecting these more vulnerable leaves.

A Tea Chemistry Lesson

Tea is often thought of as a more wholesome and less jittery source of caffeine than coffee. There is some science behind this claim. Not only does drinking tea give a lower dose of the stuff, there are other compounds present in tea which seem to influence they way our bodies respond to caffeine. Tannins are the popular new biological antioxidants, and they are said to slow down the release of caffeine into your bloodstream. They are widely found in teas, providing the ‘tannic quality’, or the astringency and richer mouthfeel of darker teas. Catechins do much the same job in green teas, both in terms of their effect on caffeine and taste.

The other little chemical to consider is L-theanine, a protein which works in synergy with caffeine to boost mood, improve cognitive function, and do all the things caffeine is sometimes said to do on its own. The narrative goes that L-theanine mitigates the negative effects of caffeine. Together, their buzz isn’t as jittery, it involves more sleep and less heart palpitations than caffeine alone might.

What Do We Think?

So, those are the facts. But how should we feel about caffeine in tea? It should essentially come down to personal experience and it also helps to look at how people drank tea before they’d even heard of catechins.

Most people simply do find tea’s buzz to be more focused and calm than that of coffee or energy drinks. Should you drink tea before bed? It depends upon whether it keeps you up at night or not, and that’s something you can tell you better than Google can. The thousands of late night tea shops that have existed for hundreds of years in China don’t switch to serving camomile to save their customers from insomnia, that much is true.

There is a fundamental truth behind the fickleness of a lot of health and diet advice we hear.

That is, we don’t actually know as much as we think we do. Especially not about the effects of chemicals and compounds on the brain. Articles and blog posts prefer being able to make concrete claims, but the advice is subject to change and the science is often still speculative.

It doesn’t make for as compelling reading, but the best thing you can do to make your mind up about caffeine in tea, is to drink some tea and see how you feel.

[1] http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2621.2005.tb08304.x/abstract