theanine

noun

the·​a·​nine ˈthē-ə-ˌnēn 

variants or L-theanine

ˈel-ˈthē-ə-ˌnēn 

: an amino acid C₇H₁₄N₂O₃ found especially in green tea and used as a dietary supplement

Green tea, which is rich in a depression-fighting amino acid called theanine, has previously been lauded for its health benefits.

—Camilla Turner

Examples of theanine in a Sentence

Recent Examples on the Web

While more research is needed, especially in younger people, L-theanine shows promise for improving mental focus—especially in the short term. —Sarah Jividen, Verywell Health, 8 Sep. 2025

The new formula also includes L-theanine, a non-protein amino acid primarily found in green and black tea and some mushrooms, Healthline states. —Greta Cross, USA Today, 5 Sep. 2025

Some people may like matcha for its higher levels of caffeine, antioxidants, and L-theanine, while others prefer the lighter flavor and lower caffeine content of green tea. —Jillian Kubala, Health, 26 Aug. 2025

Manage Your Stress Ashwagandha, St. John’s Wort, melatonin, theanine, and magnesium are commonly used to manage stress levels, as well as decrease anxiety and depression. —Allison Futterman, Discover Magazine, 13 Feb. 2025

Word History

First Known Use

1950, in the meaning defined above

Rhymes for theanine

• acridine
• alkaline
• andesine
• anodyne
• anticline
• arginine
• asinine
• atropine
• benzidine
• borderline
• byzantine
• calamine