L-theanine is a relaxing and non-essential amino acid that is found almost exclusively in teas, particularly green, oolong and black teas. It is known to promote relaxation without necessarily causing sedation, improve attention and reduce the perception of stress. (1) It is basically a nootropic, stress relief and amino acid supplement.
Its ability to promote attention and relaxation coupled with lack of sedation gives it a superior preference among athletes- it alleviates the unwanted effects of many stimulants and at the same time, has synergistic effects with them. Take for instance, a combination of L-theanine and caffeine is impressively synergistic in promoting cognition and attention. (2)
When ingested, L-theanine is absorbed in the gastrointestinal brush border membrane, specifically of the small intestines. Once absorbed into the bloodstream, it crosses the blood-brain barrier, to exert its nootropic effects. L-theanine has shown that it affects the brain wave frequency by improving alpha wave activity, the activity that is present when in the awake and alert state. It also increases dopamine levels which plays a significant role in the motivational component of reward-motivated behavior. (3) Other studies have also shown that L-theanine increases the levels of serotonin as well as GABA.
The main reason that people supplement with L-theanine is for relaxation. In several human clinical trials, L-theanine has been shown to promote relaxation through increasing alpha waves and decreasing beta waves. Alpha brain waves are dominant during quietly flowing thoughts that aid in overall mental coordination, calmness, alertness and mind-body integration. On the other hand, beta brain waves signal a more excited and non-focused mental state. Beta waves dominate high engagement, extreme excitement, and even high anxiety. (4) The high continuous frequency processing required by beta waves is not an efficient way to run the brain, especially just before a competition (it takes a tremendous amount of energy)- save that for when one has won or has smashed their goals. L-theanine, therefore, promotes relaxation by balancing these two critical brain waves. Another way in which L-theanine promotes relaxation is by decreasing anxiety and reducing rises in blood pressure that can accompany psychological stress. When the body experiences stress, the nervous system produces hormones such as cortisol that elevate blood pressure and feelings of tension.
In a study (5) published in the Journal of Psychological Anthropology, 16 healthy volunteers were given 200mg of L-theanine for a period of 7 days. The participants were then given mental tasks to perform, and later, their moods were assessed using Profile of Mood States and Visual Analogue Scales. The results showed that administration of L-theanine significantly affected systolic and diastolic blood pressure and reduced anxiety.
L-Theanine also appears to promote nitric oxide release by phosphorylating the endothelial variant of nitric oxide enzyme (eNOS). (6) The inner lining of blood vessels uses nitric oxide to signal the smooth muscle cells to cause vasodilation, consequently increasing blood flow. Good blood circulation to the brain delivers oxygen, glucose and other vital nutrients required for cognitive processes and mental focus.
As mentioned before, unlike other relaxant supplements or drugs, L-Theanine does not cause any drowsiness. This is one of the most appealing aspects of L-theanine. That means that it is a good choice for athletes that are keen on enhancing the wakeful relaxation without worrying about being sleepy and fatigued throughout the day.
The usage of caffeine benefits physical and mental performance and is one of the most widely used stimulants globally. A single dose is enough to improve exercise performance, focus, and fat burning because of its ability to cross the brain and muscle cells. (7) Since both caffeine and L-theanine improve cognitive and neurophysiological measures of selective attention, they potentiate each other. Thus, their combination even makes their effects more magical. (8)There are several ways in which L-theanine potentiates caffeine.
First, L-theanine through its action of improving blood flow to the brain, it facilitates more of caffeine to reach the neurons, for it to exert its effects. In addition, L-theanine eliminates the vasoconstrictive effects of caffeine in high levels, reducing the headaches that are common with the continued use of caffeine. (9) Second, while L-theanine acts mainly on glutamate (the main excitatory neurotransmitter) receptors, caffeine mostly inhibits adenosine signaling. This means that they both work on the brain cells but on different receptors. They, therefore, do not compete for the same binding sites.
Third, L-theanine counteracts the side effects of caffeine. (10) The downside of caffeine is that it increases the heart rate, blood pressure, anxiety and unpleasant energy crashes- the big price of being awake and aware. L-theanine stops the excessive neuronal firing, reducing the jitters and nervousness brought about by caffeine while increasing the effectiveness of the positive effects.
L-theanine protects brain cells from cell death, and injury. Other studies suggest that it is involved in the development of the hippocampus- part of the brain that stores memories. How? Its intake increases the levels of Brain-derived Neurotrophic Factor (BNDF), predominantly in the hippocampus and cortex. This action promotes the development of neurons and strengthens their connections. (11)
In a systematic review (12) published in the Journal of Phytomedicine, most of the sample studies presented evidence that indeed, L-theanine affects brain function by activating working memory, reducing the reaction time, enhancing attention and alertness. Other researchers have also shown that L-theanine can help improve and slow down memory loss in people with Alzheimer’s disease and stroke. Though most of the studies have been carried out on small sample sizes, the results are promising.
They have shown that L-theanine blunts the effects of amyloid beta- memory impairment and brain cell death. (13) Amyloid beta is the man peptide component of the amyloid plaques that are found in the brains of Alzheimer’s patients. L-theanine blocks these effects through directly acting on cellular glutathione, to prevent damage to the fats that make up the brain cells.
L-theanine constitutes 1-2% of dry weight tea- meaning that one gets about 25 to 60mg per 200ml cup of tea whereas, the effective dosage is 200mg. (14) Therefore, to get the benefits discussed above, the best source of L-theanine is from a supplement, not a cup of tea. Most of the studies recommend a dose between 100 to 200mg, usually alongside caffeine. (1) When combined with caffeine, ideal doses are as from L-theanine (100mg) and caffeine (50mg). Higher doses have also been used by some athletes, without any adverse effects- though some of it goes to building more proteins.
The best time to take L-theanine supplement depends entirely on the benefit that one would like to experience. If looking for general calming effects, morning with a cup of coffee is the best time. For sleep, an hour before bedtime is perfect. It can also be taken as a pre-workout to enhance focus, motivation, and performance.
Use of L-theanine is safe, and few adverse reactions have been reported. Most of the clinical trials that have been carried out have shown that it is not only effective but also safe. In the United States, it is marketed as a dietary supplement and has been granted as GRAS (generally recognized as safe) by the Food and Drug Administration (FDA). (15)
However, some people may experience headaches, dizziness and gastrointestinal symptoms. These side effects are generally mild and fade away with time.
L-theanine was first found as a component in green tea between 1949 and 1950 in a laboratory in Kyoto, Japan. It was initially extracted from gyokuro leaves, a type of Japanese green tea. Fourteen years later in 1964, L-theanine was approved in Japan to be used as an ingredient in all food and beverages except those meant for infants. (16) Before L-theanine was extracted, monks had been using green tea for thousands of years during extended periods of meditation.
After the scientists’ discovery, green and black teas gained popularity beyond the Chinese and Japanese cultures. More and more dietary supplement manufacturers also embarked on the business of L-theanine. In the athletic world, L-theanine is now a favourite for athletes competing in high stress, performance-based sports.
Here is a quick summary of L-theanine
It is an amino acid that predominantly occurs in green tea leaves, scientifically known as Camelia Sinensis.It comprises about 2% of the weight of a dry green tea leaf.L-theanine is responsible for the unique, pleasant taste of green tea and is also behind the ultimate success of this herbal tea.It has a chemical structure similar to glutamate, and some of their effects appear to be the same while others seem to block glutamateIt is an important component that is responsible for stimulating alpha wave production of the brain, to give an effective state of relaxation and mental clarity.L-theanine also increases dopamine and serotonin levels, some of the brain’s feel-good neurotransmitters.It protects the brain by preventing oxidative damage, averting accumulation of amyloid beta and promoting the growth of new cellsImproves mental focus, learning, and memoryIs usually taken together with caffeine for best results.A typical dose of L-theanine is about 200mgIt is considered extremely safe and is designated as GRAS by the FDA. Some people may report minor side effects such as headaches and stomach upsets but are not widely reported.