What is L-theanine?
L-Theanine is a non-proteinogenic amino acid primarily found in green tea (Camellia sinensis) and some mushrooms. It is known for its strong antioxidant-like properties and contributes to the umami taste sensation of green tea [1]. L-Theanine is also available in pill or tablet form and is often used as a supplement for its potential health benefits [2].
This amino acid has been reported to have numerous therapeutic effects, including improvements in brain and gastrointestinal function, cancer drug therapeutic efficacies, antihypertensive effects, and improved immune function [1]. It is also known to promote relaxation and improve concentration and learning ability [3].
L-Theanine has been commercially developed as a valuable ingredient for use in food and beverages to improve and/or maintain human health [3]. It is also used as a safe food additive in beverages or foods due to its varied bioactivities [4].
Based on the available scientific literature, there is no evidence to suggest that L-theanine, a major nonprotein derivative amino acid found in tea, causes cancer. In fact, several studies have indicated that L-theanine may have potential anticancer effects. You can also check out a deeper dive into L-theanine here.
The Anticancer Effects of L-Theanine
Research has shown that L-theanine can have beneficial effects on various cancer cell lines, including lung cancer, leukemia, prostate cancer, and melanoma. It has been found to suppress the growth of these cancer cells and inhibit their migration and invasion [5, 6, 7, 8].
In a systematic review of 14 studies, L-theanine was found to have moderate apoptotic (cell death-inducing), antimetastatic (preventing cancer spread), antimigration, and anti-invasion effects, along with a mild antiproliferative (growth-inhibiting) influence on cancer [5].
In a study on human lung cancer and leukemia cells, L-theanine suppressed the growth of these cells in a dose- and time-dependent manner. It also inhibited the migration of lung cancer cells [6].
In prostate cancer cells, L-theanine was found to suppress invasion, migration, and increase cell-cell adhesion [7].
In melanoma cells, L-theanine reduced cell viability, attenuated proliferation and migration, and promoted apoptosis (programmed cell death) [8].
Theanine and Chemotherapy
L-theanine has also been associated with amplifying the anti-tumor effects of certain chemotherapy drugs. It has been suggested that L-theanine could help improve chemotherapy's ability to fight cancer [2].
However, it's important to note that while L-theanine itself does not have confirmed or direct side effects, teas that contain amino acids can have other ingredients that could be harmful to people being treated for cancer. For example, the polyphenol EGCG found in green tea can reduce the efficacy of some chemotherapy drugs, such as bortezomib [2]. Therefore, it's crucial for those taking chemotherapy drugs to talk with their healthcare provider before drinking green tea as part of their treatment plan.
In conclusion, while more research is needed to fully understand the potential anticancer effects of L-theanine, current evidence does not suggest that L-theanine causes cancer. Instead, it may have potential anticancer properties.
