Monday, September 3, 2012

Green Tea May Boost Working Memory

In the European Journal of Clinical Investigation there is a recent report that green tea has yet another demonstrated benefit to good health--increasing "working" memory.

Working memory is the function of the brain that holds information so it can be used for decision making (the "executive function" of the prefrontal cortex) and reasoning. Without working memory, we cannot use our experiences and learning to make the judgments that make life easier.

Professor Stephan Borgwardt of the University Hospital in Basel, Switzerland recruited volunteers to drink either a sports drink containing whey and green tea polyphenols or a sports drink containing only whey and no green tea polyphenols. He then measured brain activity with MRI (magnetic resonance imaging). The volunteers were tested twice, with neither the volunteers or the researcher knowing which beverage they had consumed until after results had been recorded.

Green tea extract had little effect on the brain as a whole, but increased the activity of the dorsolateral prefrontal cortex. This part of the brain is involved in planning and organization. It is also the part of the brain activated during lucid dreaming and the part of the brain that makes it possible for us to engage in deception--our brains having a natural propensity for truth-telling.

The polyphenols that seem to activate this part of the brain are EGCG (epigallocatechin gallate), epigallocatechin, epicatechin, and epicatechin gallate. These substances are especially abundant in green tea, about half as abundant in oolong tea, and present in much smaller amounts in black tea.

Does this mean that drinking tea makes you "brainy?" Well, not exactly, but up to 500 mg of green tea catechins, an amount only available from taking supplements, may increase higher-level brain activities for several hours at a time.

Image credit: 緑茶(2005年2月 MASA自宅で撮影)

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