Single Dose of L-Theanine Improves Working Memory and Attention in Older Adults

by | Oct 13, 2021 | 2021, Amino Acids, Brain Health

Written by Chrystal Moulton, Staff Writer. Reaction time (p= 0.017) and working memory (P<0.05) were significantly improved following single dose of 100mg L-theanine.

agingL-theanine is an amino acid most commonly found in green tea 1 and mushrooms 2. Studies in mice show L-theanine can improve learning ability and behavior under social stress 3,4 and improves memory 5. L- theanine has also been shown to suppress delayed neuronal cell death in the hippocampal Cornu Ammonis 1 area after transient ischemia 6 and promotes neurogenesis 7. In the current study, researchers wanted to assess the effect of L- theanine on working memory, executive function, and attention 8.

Of the 69 healthy participants eligible for this double blind, randomized, placebo- controlled parallel group study, 52 participants (aged 50-69 years old) were randomized to receive either L- theanine (100.6mg) or placebo (corn starch) for 12 weeks. Participants were instructed to take one capsule per day in the morning. They also recorded whenever they consumed their designated test capsule for compliance purposes. Blood sampling, anthropometric measures, and cognitive testing was conducted at baseline and 12 weeks. Upon administration of the first dose, researchers conducted cognitive testing to determine immediate effects L-theanine supplementation. Cognitrax was used to evaluate cognitive functioning. The Mini Mental State Examination- Japanese version was used to assess attention. The primary outcomes were results of the Mini Mental State Examination and Cognitrax test. Secondary end points were blood levels of amyloid beta proteins and brain derived neurotrophic factor.

A total of 24 participants were allocated to the placebo group and 26 participants to the theanine group. No significant difference was observed in scores on the Mini Mental State Examination between both groups before and after the intervention. After a single dose of L- theanine, reaction time was significantly lower in the L- theanine group compared to the placebo group (365 ± 62.0 VS. 337 ± 84.0, P= 0.017). Furthermore, improvements were observed in the theanine group for working memory after the first dose of L-theanine (P< 0.05). No significant differences were observed between the intervention group and placebo at week 12. Also, no significant differences were observed in amyloid beta levels and brain derived neurotrophic factor between either group throughout the trial.

Overall, a single dose administration of L-theanine significantly reduced reaction time in attention tasks and improved working memory in adults. Further studies will be needed to confirm these results.

Source: Baba, Yoshitake, Shun Inagaki, Sae Nakagawa, Toshiyuki Kaneko, Makoto Kobayashi, and Takanobu Takihara. “Effects of L-theanine on cognitive function in middle-aged and older subjects: A randomized placebo-controlled study.” Journal of Medicinal Food 24, no. 4 (2021): 333-341.

© Yoshitake Baba, et al., 2021; Published by Mary Ann Liebert, Inc. This Open Access article is distributed under the terms of the Creative Commons Attribution Noncommercial License [CC-BY-NC] (http://creativecommons.org/licenses/by-nc/4.0/) which permits any noncommercial use, distribution, and reproduction in any medium, provided the original author(s) and the source are cited.

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Posted October 13, 2021.

Chrystal Moulton BA, PMP, is a 2008 graduate of the University of Illinois at Chicago. She graduated with a bachelor’s in psychology with a focus on premedical studies and is a licensed project manager. She currently resides in Indianapolis, IN.

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