L-Theanine is a non-essential amino acid commonly found in black and green tea leaves and plays a fundamental role in maintaining a healthy mental state. Research indicates L-theanine promotes healthy, fast-acting relaxation without causing drowsiness. L-theanine supplementation has grown in popularity in recent years to help people ease stress and unwind. In this 3-minute article, we are going to go over and answer the question, "what is L-theanine used for?"
Besides water, tea is the most widely consumed beverage in the entire world. Tea is known not only for its wide variety of flavors and types but also for its unique amino acid, L-theanine, which has many beneficial effects on brain function. As reported by Unilever Food and Health Research Institute, "evidence from human electroencephalograph (EEG) studies show that L-theanine has a direct effect on the brain. L-theanine significantly increases activity in the alpha frequency band which indicates that it relaxes the mind without inducing drowsiness."
Five randomized-controlled trials with a total of 104 participants found L-theanine successfully reduced stress and anxiety in individuals who were experiencing stressful situations. An additional separate study confirmed that L-theanine increases relaxation without causing drowsiness and can safely reduce resting heart rate.
Recent studies suggest L-theanine can also be quite beneficial for a good night's rest. Researchers found that doses of 250 mg to 400 mg of L-theanine greatly improved sleep quality in not only humans but animals (of all kinds) as well. Research also suggests L-theanine can improve sleep quality and duration in individuals diagnosed with schizophrenia—a disorder that is characterized by, "thoughts or experiences that seem out of touch with reality, disorganized speech or behavior, and decreased participation in daily activities."
This is where L-theanine is extremely unique: even though L-theanine can improve relaxation and decrease stress and anxiety, when paired with caffeine this beneficial amino acid can actually increase focus and attention especially during demanding tasks. A 2013 study found that moderate levels of both L-theanine and caffeine when paired together, increase focus and attention. The participants of the study—a group of young adults, found they focused better during demanding tasks and felt less tired in general. These effects can be felt in as little as 30 minutes.
Studies suggest L-theanine can improve the function of the body's immune system. For instance, one study published in the journal Beverages found L-theanine can help reduce the incidences of upper respiratory tract infections. Another study, although more research is needed to expand and certify these findings found L-theanine can help improve inflammation in the intestinal tract.
L-theanine has shown the ability in numerous scientific studies to safely and effectively lower blood pressure in stressful situations. A 2012 study, for example, observed people who normally experienced higher blood pressure after certain tasks and found that L-theanine helped control blood pressure in those groups.
Research suggests that a cup of (green) tea may provide you with some sinusitis relief. Author of the Whole Body Approach To Allergy and Sinus Health, Murray Grossman, MD, states that L-theanine can help boost cilia movement in the nose. Cilia are hair-like strands that can clear up mucus that can be impacted by an infection.
The authors of a 2011 study suggest that L-theanine found in the bay bolete mushroom works together to improve the effectiveness of certain chemotherapy drugs—one of them being doxorubicin. Certain biotechnology researchers are taking these promising studies to the next level and expect that in the future L-theanine could also help improve chemotherapy's ability to fight cancer.
L-theanine is safe to take and there are no confirmed direct side effects. As reported by Healthline, however, "according to Memorial Sloan Kettering Cancer Center, the polyphenol EGCG found in green tea can reduce the efficacy of some chemotherapy drugs while increasing the efficacy in others. For that reason, it’s very important for those taking chemotherapy drugs to consult their doctors before drinking large amounts of green tea as part of their treatment plan."