effect of green tea and its polyphenols on the lifespan of model organisms: a systematic review

Green tea contains phenolic compounds such as catechins and theanine that are known to exert positive effects to health in various organisms. the aim of this review is to determine the effect of green tea on the lifespan on healthy model organisms. pubmed and scopus databases systematically searched according to predefined eligibility criteria by three reviewers. the initial 400 titles were screened for duplicates. after exclusion of duplicates, review papers, human studies, in vitro studies and studies using unhealthy organisms, a total of 29 research articles were assessed. the articles selected reported on models namely caenorhabditis elegans (n=9), rodents (mice and rats, n = 8), drosophila melanogaster (n = 11) and african honeybees (n = 1). in most studies, green tea extracts and catechins significantly increased the mean and median lifespan of the organisms. generally, discrepancies of results within the same model organism were due to differences in the species, gender, sample size and experimental conditions used. the reviewed studies presented evidence that green tea and its constituents influence the lifespan of different healthy organisms. the effects of green tea are attributed to multiple components present in the tea. this is supported by various findings that reported modulation of lifespan when whole green tea extracts and isolated compounds were used.