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

Its lower caffeine content and the presence of L-theanine – an amino acid found naturally in tea – may also promote a calmer, more sustained sense of focus. —Daryl Austin, USA Today, 20 Feb. 2026

Matcha delivers a steady boost of energy and improves mental focus through a combination of caffeine and the amino acid L-theanine. —Lindsay Curtis, Health, 16 Feb. 2026

There are also other components in caffeinated beverages – particularly tea – that can provide brain boosting effects such as polyphenols and L-theanine which may guard against oxidative stress and support cerebrovascular function. —New Atlas, 15 Feb. 2026

Avoid taking l-theanine while pregnant or breastfeeding. —T'keyah Bazin, Verywell Health, 4 Feb. 2026

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