Why Does the L-Theanine Content of Tea Vary?

Tea is a unique source of an amino acid called L-theanine. L-theanine is of interest to nutritionists because evidence suggests that L-theanine can alter brain chemistry which result in changes to brain wave pattern. These changes cause the excitability of the brain to be diminished such that the overall effects of L-theanine are to cause a calming effect. Studies have investigated the L-theanine content of various teas, and the findings from these studies indicate that there is a large variation in the L-theanine content. One study investigated this variation by measuring the L-theanine content of two types of leaf, one of which was known to contain much higher concentrations of L-theanine. The observations of the researchers lead them to conclude that the reason that the high L-theanine leaf was able to accumulate more L-theanine was because the degradation of L-theanine to L-glutamate in the leaves was inhibited. Therefore certain tea varieties may accumulate more L-theanine due to reduced capacity to metabolise it.

tea l-theanine

Tea is a source of L-theanine, but the L-theanine content of tea can vary considerably between varieties and between batches of tea. Therefore an effective way to maintain a consistent intake of L-theanine is to take a supplement with a known amount of L-theanine.

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Cheng, S., Fu, X., Liao, Y., Xu, X., Zeng, L., Tang, J., Li, J., Lai, J. and Yang, Z. 2019. Differential accumulation of specialized metabolite L-theanine in green and albino-induced yellow tea (Camellia sinensis) leaves. Food Chemistry. 276: 93-100

About Robert Barrington

Robert Barrington is a writer, nutritionist, lecturer and philosopher.
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