4 Stimulants in Tea You Should Know
There are 4 substances in tea that are able to cross the blood-brain barrier to provide a stimulant effect. We have good, old caffeine, which you can also get from coffee and soft drinks. 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.
Caffeine is the world’s most widely used psychoactive substance. 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. 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.
Theophylline and Theobromine
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.
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.