A bowl of prepared matcha tea on a wooden surface, with a heap of matcha powder, a spoon, and a bamboo whisk, showcasing the tea-making process

L-Theanine and Cognitive Function

L-theanine, a non-protein amino acid primarily found in green tea, has garnered significant attention for its potential cognitive benefits.

This compound is known for its ability to cross the blood-brain barrier, exerting various effects on brain function. Recent research has focused on how L-theanine can enhance cognitive performance, particularly in middle-aged and older adults.

This blog will review a recent study that investigates the impact of L-theanine on cognitive functions such as attention, working memory, and executive function.

Can a simple cup of green tea truly enhance your memory and attention? Let's explore the science behind this intriguing question.



  • Background
  • Study Overview
  • Results
  • Discussion


L-Theanine and Cognitive Function


A glass cup of green tea with a tea bag steeping inside, placed on a cork coaster with fresh mint leaves beside it, set against a green background



Historically, L-theanine has been consumed through green tea for its calming effects and various health benefits. In Japan, teas like gyokuro and matcha, which contain higher levels of L-theanine compared to other teas, have been particularly prized.

In modern times, L-theanine has attracted scientific interest due to its potential mental health benefits, including stress reduction and mood improvement. Beyond these effects, L-theanine is reputed to support cognitive functions such as attention and memory.

Its ability to induce relaxation without drowsiness makes it a unique and valuable nootropic, appealing to those seeking to enhance their mental performance naturally.


Study Overview

The study titled "Effects of L-Theanine on Cognitive Function in Middle-Aged and Older Subjects" by Yoshitake Baba and colleagues, published in 2021, provides a thorough investigation into the cognitive benefits of L-theanine.

The primary aim of the research was to determine which specific cognitive functions are positively influenced by L-theanine intake. This study is particularly relevant given the increasing interest in non-pharmaceutical interventions for cognitive enhancement.

To achieve this, the researchers conducted a double-blind, randomized, placebo-controlled trial involving 69 Japanese participants aged between 50 and 69 years. These participants were selected based on their self-reported cognitive decline and confirmed through baseline cognitive assessments using the Mini Mental State Examination-Japanese version (MMSE-J).

The study utilized the Cognitrax test battery, a comprehensive tool for evaluating various aspects of cognitive function, including attention, working memory, and executive function.

Participants were divided into two groups, receiving either L-theanine or a placebo over a 12-week period. Cognitive performance was assessed at baseline, after a single dose of L-theanine, and following the 12-week supplementation period. This rigorous methodology ensured the reliability and validity of the findings, providing valuable insights into the cognitive effects of L-theanine in an aging population.




The study demonstrated that L-theanine intake significantly enhanced attention and working memory in middle-aged and older adults.

Participants who consumed L-theanine showed marked improvements in cognitive tasks. For instance, the reaction times in the Stroop test (Part 1) were significantly lower in the L-theanine group compared to the placebo group, with reaction times decreasing from 378 ± 138 ms to 337 ± 84 ms (p < 0.05).

In the four-part continuous performance test (Part 4), the number of correct responses increased significantly, from 11.8 ± 3.4 to 13.4 ± 2.8, while omission errors decreased from 1.15 ± 2.3 to 0.12 ± 0.33 (p < 0.05).

These quantitative results highlight L-theanine's efficacy in enhancing specific cognitive functions, offering a statistically significant improvement over the placebo.



The findings of this study align well with the existing body of knowledge regarding L-theanine's neuroprotective and cognitive-enhancing properties. Previous research has indicated that L-theanine can alleviate stress, improve mood, and support normal sleep patterns, all of which contribute to cognitive health. The observed improvements in attention and working memory are consistent with these neuroprotective effects.

However, the study's limitations must be acknowledged. It focused exclusively on middle-aged and older adults, which means the results may not be generalizable to younger populations or those with different health conditions. Further research is needed to explore the effects of L-theanine across diverse demographic groups and to understand the long-term impact of its consumption.

From a practical perspective, incorporating L-theanine into the daily diet, possibly through green tea or supplements, could offer significant cognitive benefits. For those looking to enhance their mental performance, L-theanine provides a natural and accessible option. Given its safety profile and the positive outcomes observed, it is a promising candidate for further investigation and everyday use.



L-theanine demonstrates significant promise in enhancing attention and working memory among middle-aged and older adults.

The study's findings support its efficacy as a cognitive enhancer, with notable improvements in reaction times and accuracy in cognitive tasks. We encourage readers to explore the benefits of L-theanine by incorporating green tea into their daily routines and to share their experiences.

This simple addition to your diet could provide valuable cognitive support, contributing to improved mental performance and overall brain health.


Learn more about the vitamins, minerals and natural nootropic plant extracts we use to give your brain a daily boost 

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