An interventional study of Green tea and green coffee extract tablets in Diet, Food, and Nutrition and Dietary Supplements, sponsored by MRC Human Nutrition Research. Completed at 1 site in United Kingdom. Open to participants aged 18 Years to 45 Years, including healthy volunteers. Per ClinicalTrials.gov, last updated 2017-08-21.
Sponsored by MRC Human Nutrition Research · Not applicable, Interventional, and Basic science
There is little information on the dietary intake, absorption, metabolism and bioavailability (degree to which a substance becomes available to the target tissues upon administration) of polyphenols (natural substances present in a variety of foods) in human participants.
This study assessed the bioavailability in healthy participants of polyphenols from 2 supplements containing green tea and green coffee extracts.
Eleven participants were recruited and their habitual diet was assessed to estimate polyphenol intake. After completing a 24-hour urine collection, participants were given six green tea extract and three green coffee extract tablets, which they took daily for a period of 8 weeks. No tablets were taken during the last 4 weeks of the study. Further 24-hour urines were collected at 2, 4, 8 and 12 weeks.
Participants were required to attend HNR (medical laboratory) the day after each 24hour urine collection. At these visits, they were asked to bring along their urine collections, completed documents (urine collection sheet, checklist for tablet intake/side effects) and any remaining supplements, which were used to assess tablet compliance.
The investigators identified and quantified the amount of polyphenols in the supplement tablets as well as the amount of polyphenols and their metabolites in urine. The investigators then evaluated polyphenol bioavailability from the relationship between their dietary intake and urinary output.
Evidence from this research could inform future intervention studies by providing data on the bioavailability of green tea and coffee polyphenols, and on the individual differences related to phenolic intake.
This is the only study on the registry with MRC Human Nutrition Research as lead sponsor.
Counted across the registry records on this site, refreshed daily.
Go through the criteria one by one — yes, no or not sure — and take the list to your doctor or the study team. Kept in this browser only.
Exclusion Criteria:
1. Tablets: participants were required to take 6 green tea and 3 green coffee extract tablets daily for a period of 8 weeks. No tablets were taken during the last 4 weeks of the study. Randomly chosen tablets were analysed to quantify their polyphenol content. 2. Urine collections: Several urine collections were required during the supplementation period in order have sufficient time points to estimate the plateau of the concentration of green tea and coffee polyphenols excreted in the urine to then be able to determine their bioavailability. There was a total of five 24-hour urine collections (at week 0 -before supplementation-, 2, 4, 8, and 12 -4 weeks after finishing the supplementation period). 3. Completion of study documents: Participants were provided with urine collection sheets, polyphenol questionnaires, checklists to record polyphenol tablet intake, and detailed instructions.
Change from baseline phenolic metabolites in urine at 2 weeks
Assessment of the profile of metabolites coming from green tea and green coffee phytochemicals in urine
Time frame: Week 0 -before supplementation- and week 2
Change from baseline phenolic metabolites in urine at 4 weeks
Assessment of the profile of metabolites coming from green tea and green coffee
Time frame: Week 0 -before supplementation- and week 4
Change from baseline phenolic metabolites in urine at 8 weeks
Assessment of the profile of metabolites coming from green tea and green coffee
Time frame: Week 0 -before supplementation- and week 8
Change from baseline phenolic metabolites in urine at 12 weeks
Assessment of the profile of metabolites coming from green tea and green coffee
Time frame: Week 0 -before supplementation- and week 12 -4 weeks after finishing the supplementation period-
Phenolic compounds in tablets
Quantification of the tablet polyphenol content
Time frame: Through study completion, an average of 3 months
Plan to share: No
No publications or documents are linked to this record.
Ran from Apr 2013 to primary completion in Oct 2013, 6 months.
How these figures are worked out, and which studies are left out of them.
This study is completed, as verified in Aug 2017. You cannot join it, but the record below documents what was studied.
Get an email when the registry record changes — status, dates, results — or when someone posts here.
Sign in to followQuestions and observations about this study, from anyone following it. Not medical advice, and not a channel to the study team — their contact details are on the registry record.
Sign in to join the discussion. Reading takes no account; posting does. You choose a display name, and a pseudonym is the default.
Nothing here yet. If you are running this trial, taking part in it, or weighing whether to, this is the place to say so.