Hippuric acid as a major excretion product associated with black tea consumption

1. Nine habitual tea-drinking volunteers were recruited and asked to follow a low-polyphenol and low-caffeine diet for 6 days and to provide daily 24- h urine samples. On day 1 of the experiment strong black tea brewed under s tandardized conditions was reintroduced to the volunteers' diet. 2. H-1-NMR and HPLC profiling of the urine samples indicated that consumpti on of black tea (6-10 mugs per day) was associated with a significant (p = 0.00017) increase in hippuric acid excretion relative to control, increasin g from 153-512 to 742-1374 mg day(-1). The excretion of substantial amounts of hippuric acid has nor previously been associated with black tea consump tion. 3, For some volunteers. the quantity of benzoic acid processed exceeded the acceptable daily intake (ADI), but this is not considered to constitute an y hazard. 4. ii mass-balance analysis indicated that the necessary quantity of benzoi c acid could not be obtained from the: contents of gallic acid, flavanols, flavonol glycosides and theaflavins in black tea even if 100% transformatio n was obtained, suggesting that the thearubigins (the major and chemically ill-defined polyphenols of black tea) may be an important source.