Sure enough, there is good research out there to indicate that the catechin most often talked about in green tea -- EGCG -- interferes with platelet aggregation. Near as I can tell, the studies so far are all about stirring the EGCG into platelets in test tubes (as opposed to human-based studies), but there are plenty of studies out there with similar findings.
There are a few studies that suggest other catechins in green tea may have the opposite effect, but that's a newer line of research and the results don't seem to be as well established.
I found some anecdotal reports from folks who think green tea lowered their platelet counts, but couldn't find any science on that aspect. Instead the documented problem seems to be that the EGCG interferes with the signals that tell platelets to stick together and clot.
Some of the other catechins in green tea seem to have the opposite effect of EGCG, but the research on that is thinner.
Based on all that, if I had really low platelets and bleeding or bruising problems, I'd be very careful about green tea.
Thanks for the heads up tytd!
Greg, 59, dx MDS RCMD Int-1 03/10, 8+ & Dup1(q21q31). NIH Campath 11/2010. Non-responder. Tiny telomeres. TERT mutation. Danazol at NIH 12/11. TX independent 7/12. Pancreatitis 4/15. 15% blasts 4/16. DX RAEB-2. Beginning Vidaza to prep for MUD STC. Check out my blog at www.greghankins.com