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

Abstract

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 4 of the experiment strong black tea brewed under standardized conditions was re-introduced to the volunteers' diet. 2. 1H-NMR and HPLC profiling of the urine samples indicated that consumption of black tea (6-10 mugs per day) was associated with a significant (p = 0.00017) increase in hippuric acid excretion relative to control, increasing from 153-512 to 742-1374 mg day(-1). The excretion of substantial amounts of hippuric acid has not previously been associated with black tea consumption. 3. For some volunteers, the quantity of benzoic acid processed exceeded the acceptable daily intake (ADI), but this is not considered to constitute any hazard. 4. A mass-balance analysis indicated that the necessary quantity of benzoic acid could not be obtained from the contents of gallic acid, flavanols, flavonol glycosides and theaflavins in black tea even if 100% transformation was obtained, suggesting that the thearubigins (the major and chemically ill-defined polyphenols of black tea) may be an important source.

In Vitro Bioconversion of Polyphenols from Black Tea and Red Wine/Grape Juice by Human Intestinal Microbiota Displays Strong Interindividual Variability

“…This is in line with earlier indications that β-oxidation of dietary flavonoids only occurs in host tissues (25). In vivo, 3-phenylpropionic acid is known to be absorbed by the host, usually converted to benzoic acid, conjugated with glycine to hippuric acid that is finally excreted in urine (26). In comparison, hydroxylated phenylacetic acids are not further metabolized after absorption or methylated in the liver before their urinary excretion (23).…”

The Use of a Novel Ferulic Acid Esterase from Lactobacillus acidophilus K1 for the Release of Phenolic Acids from Brewer's Spent Grain

“…Due to the limited degradation in the intestines, simple phenolic acids can exhibit antioxidant activity in vivo 14 . A considerable content of phenolic acids was found in blood and in urine after the consumption of different foods 7,10,11 . It must be emphasized that the more complex phenolic compounds are broadly consumed and exert strong antioxidant activities in vitro but they are easily degraded in the gastrointestinal tract 29,52,53 .…”

Phenolic acids from malt are efficient acetylcholinesterase and butyrylcholinesterase inhibitors

“…After in vivo absorption, phenolic acids are transformed only to a limited extent in comparison to more complex phenolic compounds (73)(74)(75)(76)81). Polyphenols are easily degraded to simple phenolic compounds, yielding phenolic acids that are absorbed into the blood circulation system (79,80,(83)(84)(85).…”