L-Theanine is an amino acid which naturally occurs in tea leaves and some forms of mushrooms. Tea (Camellia sinensis) contains 1-3% of L-theanine. It is used in a supplemental form isolated directly from tea leaves or prepared via chemical synthesis or biosynthesis. Green, black, oolong and white tea all contain L-Theanine in varying amounts.
L-Theanine is absorbed through the intestines and reaches the blood-brain barrier in approximately 50 minutes after ingestion, similarly to the absorption through natural tea leaves. L-Theanine can be found in the brain in the hippocampus (3) after ingestion–the area of the brain responsible for learning and memory.
Research suggests that L-Theanine (L-gamma-glutamylethylamide) works through glutamate receptors and increases levels of GABA and glycine in the brain, which causes relaxation. Increased GABA and glycine may increase serotonin and dopamine; however, it has also been noted that theanine may decrease or inhibit serotonin synthesis.
Caffeine is a stimulant found in coffee, tea, chocolate, guarana, yerba mate, and the kola nut. It is an adenosine receptor antagonist, meaning that it prevents adenosine from being active. Adenosine is one of the neurotransmitters responsible for drowsiness, and caffeine provides wakefulness through this mechanism of blocking adenosine.
Caffeine also interacts with the serotonergic system and can cause changes in the acetylcholine and dopamine systems within the body. Caffeine does produce side effects, such as large amounts acutely raising blood pressure. Mild side effects can include anxiety, agitation, restlessness, fidgeting, irritability, elevated or irregular heart rate, and others.
L-Theanine + Caffeine Combination
By combining L-theanine with caffeine, some of the undesirable side effects of caffeine use are lessened. L-Theanine reduces caffeine’s stimulatory effects without modifying the other mechanisms for focus that caffeine offers. L-Theanine interacts with caffeine by “taking the edge off” and still allows the alertness provided by caffeine to remain.
The combination of L-theanine with caffeine also may improve cognitive function, may eliminate the blood vessel constriction normally experienced with caffeine, and help keep the mind from experiencing wandering, or distraction.
The cognitive benefits associated with caffeine in combination with L-Theanine were studied on 50 mg caffeine to 100 mg L-Theanine, so we recommend caffeine to L-Theanine ratio should be 1-part caffeine to 2 parts L-Theanine.