Green tea effects on cognition, mood and human brain function: A systematic review

Area of Science:

• Neuroscience
• Nutritional Science
• Psychology

Background:

• Green tea (Camellia sinensis) has a long history of consumption.
• Its popularity is increasing globally, necessitating an understanding of its brain effects.
• Numerous health claims associated with green tea require scientific investigation.

Purpose of the Study:

• To review existing literature on the neuropsychological effects of green tea.
• To assess the impact of green tea, l-theanine, and epigallocatechin gallate on human cognition and brain function.
• To synthesize current knowledge on green tea's influence on general neuropsychology.

Main Methods:

• Systematic literature search conducted on the PubMed database.
• Studies selected based on predefined eligibility criteria.
• Study quality assessed using adapted DELPHI-list and Newcastle-Ottawa scales, following PRISMA guidelines.

Main Results:

• A total of 21 studies were reviewed, including randomized controlled trials, cross-over, cross-sectional, and cohort studies.
• The overall quality of the included studies was rated as good.
• Evidence suggests green tea influences psychopathological symptoms and cognitive functions.

Conclusions:

• Green tea consumption is linked to reduced anxiety and improved memory and attention.
• Functional MRI studies show activation of working memory associated with green tea.
• Beneficial effects are attributed to the synergistic action of green tea constituents, notably caffeine and l-theanine.