Olthof M.R., Hollman P.C., Buijsman M.N., van Amelsvoort J.M., Katan M.B. (2003) Chlorogenic acid, quercetin-3-rutinoside and black tea phenols are extensively metabolized in humans. J Nutr 133:1806-14 PubMed (12771321)

Compound Mean content
Polyphenols, total 4.3 mmol/4 g dry weight