Small studies and tests on animals have shown that L-theanine may offer a range of benefits. Experts consider it to be generally safe, but there is currently a lack of high-quality research in humans to confirm its benefits. Many people drink black or green tea while at work, believing that it boosts their mental focus. A study supports this idea. The researchers found that people who took milligrams mg of L-theanine made fewer errors in an attention task than those in the placebo group.
L-theanine may help people sleep more easily. Several studies have suggested that L-theanine could help people relax before bedtime, get to sleep more easily, and sleep more deeply. These benefits may result from the specific effects that the amino acid has on brain chemicals that play a role in sleep. A study found that people reported having greater sleep satisfaction after taking — mg of L-theanine daily for 8 weeks.
The study participants had generalized anxiety disorder and were taking antidepressants. The authors noted that there were no reported improvements in anxiety or insomnia severity. People often drink a cup of tea or another hot beverage to help them relax. They noted that it seems to have neuroprotective effects, which improve brain function. In combination with caffeine, it may lead to improvements in their number skills and alertness.
Caffeine is a stimulant, so it can help people stay alert and focused. As part of a calorie-controlled diet, replacing a snack with green tea or another low-calorie hot beverage could aid weight loss. The L-theanine in green tea can create a savory taste, also known as umami flavor.
Research suggests that umami flavors may reduce appetite, which often helps with weight loss. L-theanine may support the body in fighting off illness. Research has linked high blood pressure with a higher risk of several health problems, including heart attack and stroke. L-theanine may help reduce stress, and a reduction in stress and increased relaxation can lower the heart rate.
In turn, this may help lower blood pressure. Some research on animals suggests that L-theanine may increase the effectiveness of a chemotherapy drug called doxorubicin. It is possible that it makes doxorubicin more effective by increasing the amount of the drug in cancer cells.
However, scientists need to do more research to understand the specific interactions between these chemicals. Scientists have not yet conducted high-quality research in humans. A stroke is the result of a sudden blockage of blood ischemia to a part of the brain, resulting in massive chemical stresses, extreme excitotoxicity, and eventual death of brain cells.
Lab studies show that L-theanine is capable of significantly improving nitric oxide production in endothelial artery-lining cells. In another stroke-preventing mechanism, L-theanine has recently been shown to significantly reduce the expression of adhesion molecules to the endothelial wall by inhibiting tumor necrosis factor alpha TNF-a , thereby reducing the risk of an artery-blocking clot or obstruction that produces a stroke.
L-theanine protects the body from the damage of blood reperfusing, or refilling that occurs after the abrupt loss of circulation during the stroke.
This ischemia-reperfusion injury results in massive release of glutamate and produces deadly excitotoxicity. Animal studies show that administration of L-theanine up to 12 hours after a stroke is induced protects brain cells and reduces the size of the damaged brain areas. Even treatment as late as 24 hours after the stroke improves neurological status.
People with schizophrenia may experience positive symptoms such as hallucinations, delusions, and paranoid thinking, as well as negative symptoms including loss of ability to experience pleasure, blunted emotions, and diminished speech capacity. Perhaps because schizophrenia may involve excitotoxic damage to brain cells, L-theanine has recently been the focus of human studies in patients with this disease.
In one study of 40 patients with schizophrenia, subjects were given placebo or mg L-theanine along with their regular medications for an eight-week trial. The supplemented patients demonstrated significant reductions in their anxiety and general symptoms of psychopathology.
A mg per day dose of L-theanine significantly improved, in a different study scores on positive symptoms, as well as in sleep quality. L-theanine, an amino acid found in green tea, reduces anxiety by blocking excitatory stimuli at glutamate receptors in the brain while stimulating production of the inhibitory, relaxing neurotransmitter GABA. But unlike prescription anti-anxiety drugs, L-theanine relieves stress without causing drowsiness or impairing motor behavior. In fact, studies show it improves alertness and attention.
Studies suggest a role for L-theanine in supporting cognitive function and preventing cognitive loss by protecting brain cells and preventing strokes and reducing the damaging effects if a stroke has occurred. Lastly, L-theanine is the subject of human studies in patients with schizophrenia. Influence of alkylamides of glutamic acid and related compounds on the central nervous system.
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