Tea, flavonoids and stroke in man and mouse

Background and purpose luate the strength of the in vivo evidence of relationships between flavonoids and risk of stroke. s iewed the literature more broadly for flavonoids and stroke and conducted an evidence-based review of original publication experiments on tea or tea components on induced coronary occlusion in animal models and on the observational epidemiology on stroke and either tea or flavonoids in man. Each of the studies was evaluated by two independent reviewers. The evidence in total was compared with the Bradford Hill [1] and Stroke Therapy Academic Industry Roundtable (STAIR)1Abbreviations Used: STAIR, Stroke Therapy Academic Industry Roundtable; EGCG, epigallocatechin gallate; MCAO, middle cerebral artery occlusion; SHRSP rats, Sprague–Dawley or Wistar rats, Mongolian gerbil, ddY mice, or spontaneously hypertensive stroke-prone rats ity-assessment criteria [2]. s arch of epidemiologic publications revealed 7 cohort studies on flavonoid intake and stroke and 7 cohort studies and 3 case control studies on tea and stroke. In studies of tea there was a consistent protective effect. However, the epidemiologic research on flavonoids and stroke was much less consistent. Eleven animal experiments were identified that examined tea or tea components and stroke relevant sequelae, eight of which reported on infarct volume. All studies demonstrated reduced infarct volumes in animals exposed either to tea extracts, theanine or tea catechins prior to or shortly after reperfusion. sions criteria of causality are largely met in the case of tea and stroke. A high level of consistency across preclinical studies, of the effect of tea components as single agents effective in reducing stroke volume after middle cerebral artery occlusion, is noted in all rodent models (rat, mouse, and gerbil). Reductions in infarct volume are seen with both tea extracts consumed orally and tea components introduced intra-peritoneally. Observational epidemiology supports this finding in man for tea – the studies are consistent across countries and type of tea and the relative risks are moderately strong. That is not the case for the body of evidence on flavonoid intakes and stroke.