Green tea could affect working memory, say researchers
Having green tea could affect parts of the brain connected to working memory.
According to the first study ever to use functional neuroimaging methods to test green tea effects on the brain, whey-based soft drinks that contain green tea is associated with increased activation in the dorsolateral prefrontal cortex – a section of the human brain linked to working memory.
Led by Professor Stefan Borgwardt from the University Hospital Basel in Switzerland, the study is the first to use functional magnetic resonance imaging (MRI) to observe changes in the brain following the consumption of green tea extracts.
Borgwardt said: “This is the first neuroimaging study implicating that functional neuroimaging methods provide a means of examining how green tea extract acts on the brain and that green tea extract enhances the engagement of brain regions that mediate working memory processing”.
The research team examined 12 healthy volunteers and asked them to perform a working memory task after consuming 250 or 500 ml of a whey-based soft drink with or without green tea extract in a double-blind, controlled repeated measures within-subject trial.
While analysis of the whole brain demonstrated no significant changes, further examination revealed that consumption of green tea extracts is associated with increased activation in the dorsolateral prefrontal cortex.
In addition, the effects were linked to the doses consumed with higher doses producing greater activation.
The study is another example to a long list of potential health effects of green tea and its extracts including minimising the risks of Alzheimer’s and particular cancers, improving cardiovascular and oral health as well as helping in weight management.
Green tea contains around one third of water-extractable polyphenols, while black tea (green tea that has been oxidised by fermentation) contains roughly just under one tenth.
Oolong tea is semi-fermented tea and roughly in between green and black tea. The four primary polyphenols found in fresh tealeaves are epigallocatechin gallate (EGCG), epigallocatechin, epicatechin gallate and epicatechin.