There are 4 substances in tea that are able to cross the blood-brain barrier to provide a stimulant effect.
Then we have two substances related to caffeine, theobromine and theophylline.
And finally we have a rather unique amino acid called L-Theanine, which has some very interesting effects on the brain.
This article discusses these 4 stimulants in tea.
The other day I was talking to a friend of mine about the psychoactive effects of coffee and tea.
Both contain caffeine and therefore have a stimulant-like effect on the brain, but we agreed that the nature of these effects is quite different.
My friend used an interesting analogy: The effect provided by tea is like being gently encouraged to do something by Mother Theresa, while coffee is like being kicked in the butt by a military officer.
After our conversation, I've been doing some reading on tea and how it affects the mind.
Don't get me wrong, I do love coffee and I believe it to be healthy. In fact, I tend to call it my all-time favorite health drink.
However, coffee does definitely have a downside for me. It tends to give me a nice and strong energy boost, but I believe it sometimes prevents me from getting much done because the "wired" feeling can cause my brain to wander.
This excessive stimulant effect of coffee can make me spend a lot of time on unproductive tasks like checking e-mails, hanging on Facebook, reading pointless news stories, etc.
It turns out that tea has less caffeine than coffee, but also three stimulant substances that may provide some sort of synergistic effect.
Bottom Line: Coffee gives a stronger boost and greater stimulating effects than tea. It can even be so powerful that it may affect your productivity.
Caffeine is the world's most widely used psychoactive substance (1).
That sounds like a bad thing, but it doesn't have to be.
Coffee, the biggest source of caffeine, also happens to be the biggest source of antioxidants in the western diet, and consuming it has been associated with various health benefits.
The second largest source of caffeine worldwide is tea, which tends to provide a moderate amount of caffeine, depending on the type.
Caffeine causes stimulation of the central nervous system, increases vigilance and reduces drowsiness.
Caffeine has several proposed mechanisms, the main one is that it is believed to block an inhibitory neurotransmitter called adenosine at certain synapses in the brain, leading to a net stimulant effect.
Adenosine is believed to increase in the brain throughout the day, building up a kind of a "sleep pressure." The more adenosine, the greater the tendency to fall asleep. Caffeine partly reverses this effect (2).
The main difference between the caffeine in coffee and tea, is that tea has a lot less of it.
Whereas a strong cup of coffee can provide 100 mg, 200 or even 300 mg of caffeine, a cup of tea may provide 20-60 mg.
Bottom Line: Caffeine blocks adenosine in the brain, an inhibitory neurotransmitter that promotes sleepiness. Tea contains much less caffeine than coffee, thereby providing less stimulating effects.
Theophylline and theobromine are both related to caffeine and belong to a class of organic compounds called xanthines.
They both have several physiological effects on the body.Theophylline relaxes smooth muscles in the airway, making breathing easier while also stimulating both the rate and force of contraction of the heart.
Theobromine can also stimulate the heart, but it does have a mild diuretic effect and improves blood flow around the body, leading to a net reduction in blood pressure.
Cocoa beans are also good sources of these two substances (3).
The amounts of these substances in a cup of tea are very small though, so their net effect on the body is probably negligible.
Some of the caffeine we ingest is metabolized into theophylline and theobromine, so every time you consume caffeine - you will indirectly increase your levels of these two caffeine metabolites.
Bottom Line: Theophylline and theobromine are organic compounds related to caffeine and found in small amounts in tea. They stimulate the body in several ways.
The last substance is by far the most interesting of the four.
It is a unique type of amino acid called L-theanine. It is mainly found in the tea plant (Camellia sinensis) and is able to cross the blood-brain barrier.
In humans, L-theanine increases generation of brain waves called Alpha waves, which are associated with alert relaxation. This is perhaps the main reason for the different, milder buzz that tea generates compared to coffee (4).L-theanine may affect neurotransmitters in the brain, such as GABA and Dopamine (5).
Bottom Line: Tea contains an amino acid called L-theanine, which increases the production of alpha waves in the brain. L-theanine, in combination with caffeine, may improve brain function.
Tea may be a suitable alternative for those who are sensitive to the high amounts of caffeine in coffee.
Due to the L-theanine and its effect on alpha waves in the brain, it may also be a better choice than coffee for those who need to concentrate for long periods of time.
I personally feel pretty good when I drink tea (green tea, in my case).
I feel relaxed, focused and I don't get the excessively wired feeling that coffee tends to give me.
However, I don't feel the same strong motivating effects of coffee, that kick that I get after drinking a strong cup.
All in all, I believe that both tea and coffee have their upsides and downsides.
For me, tea looks like the best choice when doing work on the computer or studying, while coffee is better suited for physical endeavors like working out in the gym.