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L-theanine is a an amino acid that occurs naturally in green tea and black tea, and it is also available in supplement form. Debene carries Ansiwell Fast, a food supplement for concentration and anti-stress, and Ansiwell Voyage, a food supplement against anxiety. 


Research suggests that L-theanine may provide a range of health benefits, which may include improved mental focus and better sleep quality.


According to Healthline, the benefits of L-theanine are: 


Anxiety and Stress Relief

L-theanine may be beneficial for those dealing with high levels of anxiety. Five randomized-controlled trials with a total of 104 participants found L-theanine reduced stress and anxiety in people who were experiencing stressful situations. Another study found that it increased relaxation without causing drowsiness and reduced resting heart rate.


Increased Focus

Paired with caffeine, L-theanine may help increase focus and attention. A 2013 study found that moderate levels of L-theanine and caffeine (about 97 mg and 40 mg) helped a group of young adults to focus better during demanding tasks. The study’s participants also felt more alert and less tired in general. According to another study, these effects can be felt in as little as 30 minutes.


Better Immunity

Some research suggests that L-theanine may improve the function of the body’s immune system. One study published in the journal Beverages found that L-theanine could help decrease the incidence of upper respiratory tract infections. Another study found that L-theanine could help improve inflammation in the intestinal tract. However, more research is needed to confirm and expand on these findings.


Tumor and Cancer Treatment

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. Because of these promising findings, the same biotechnology researchers expect that L-theanine could also help improve chemotherapy’s ability to fight cancer.


Blood Pressure Control

L-theanine may be beneficial for those who experience increased blood pressure in stressful situations. A 2012 study observed people who normally experienced higher blood pressure after certain mental tasks. They found that L-theanine helped control this blood pressure increase in those groups. In the same study, the researchers noted that caffeine had a similar but less beneficial effect.


Improved Sleep Quality

Some research indicates that L-theanine could be beneficial for a good night’s sleep. Researchers in one study found that doses of 250 mg and 400 mg of L-theanine greatly improved sleep in animals and humans. Also, 200 mg of L-theanine was shown to reduce resting heart rate, pointing to its ability to promote relaxation.”




  1. Healthline. Theanine. Available at:

  2. Hidese S, Ogawa S, Ota M, et al. Effects of L-Theanine Administration on Stress-Related Symptoms and Cognitive Functions in Healthy Adults: A Randomized Controlled Trial. Nutrients. 2019;11(10):2362. Published 2019 Oct 3. doi:10.3390/nu11102362.

  3. WebMD. Theanine. Available at:

  4. Wikipedia. Theanine. Available at:




All information on this webpage and website has been sourced and reported “as is” based on public sources. None of the statements on this web site have been evaluated by the US FDA, EFSA or other regulatory authority. Read More


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