Statements in which the resource exists as a subject.
PredicateObject
rdf:type
lifeskim:mentions
pubmed:issue
3
pubmed:dateCreated
2009-10-14
pubmed:abstractText
Green tea catechins (GTC) have been shown to inhibit the activities of enzymes involved in folate uptake. Hence, regular green tea drinkers may be at risk of impaired folate status. The present experiments aimed at studying the impact of dietary GTC on folate concentrations and metabolism. In a human pilot study (parallel design) healthy men consumed for 3 weeks 6 capsules (approximately 670 mg GTC) per day (2 capsules with each principal meal) containing aqueous extracts of the leaves of Camellia sinensis (n=17) or placebo (n=16). No differences in plasma folate concentrations were observed between treatments. We further fed groups of 10 male rats diets fortified with 0, 0.05, 0.5, 1, or 5 g GTC/kg for 6 weeks. Only at the highest intake, GTC significantly decreased serum 5-methyl-tetrahydrofolate concentrations in rats, while mRNA concentrations of reduced folate carrier, proton-coupled folate transporter/heme carrier protein 1, and dihydrofolate reductase (DHFR) remained unchanged in intestinal mucosa. Using an in vitro enzyme activity assay, we observed a time- and dose-dependent inhibition of DHFR activity by epigallocatechin gallate and a green tea extract. Our data suggest that regular green tea consumption is unlikely to impair folate status in healthy males, despite the DHFR inhibitory activity of GTC.
pubmed:language
eng
pubmed:journal
pubmed:citationSubset
IM
pubmed:chemical
pubmed:status
MEDLINE
pubmed:month
Sep
pubmed:issn
1899-1505
pubmed:author
pubmed:issnType
Electronic
pubmed:volume
60
pubmed:owner
NLM
pubmed:authorsComplete
Y
pubmed:pagination
103-8
pubmed:meshHeading
pubmed-meshheading:19826188-Adolescent, pubmed-meshheading:19826188-Adult, pubmed-meshheading:19826188-Animals, pubmed-meshheading:19826188-Camellia sinensis, pubmed-meshheading:19826188-Catechin, pubmed-meshheading:19826188-Chromatography, High Pressure Liquid, pubmed-meshheading:19826188-Diet, pubmed-meshheading:19826188-Dose-Response Relationship, Drug, pubmed-meshheading:19826188-Double-Blind Method, pubmed-meshheading:19826188-Folic Acid, pubmed-meshheading:19826188-Folic Acid Antagonists, pubmed-meshheading:19826188-Humans, pubmed-meshheading:19826188-Male, pubmed-meshheading:19826188-Middle Aged, pubmed-meshheading:19826188-Pilot Projects, pubmed-meshheading:19826188-Plant Extracts, pubmed-meshheading:19826188-Questionnaires, pubmed-meshheading:19826188-Rats, pubmed-meshheading:19826188-Rats, Wistar, pubmed-meshheading:19826188-Tetrahydrofolate Dehydrogenase, pubmed-meshheading:19826188-Young Adult
pubmed:year
2009
pubmed:articleTitle
Greeen tea extracts lower serum folates in rats at very high dietary concentrations only and do not affect plasma folates in a human pilot study.
pubmed:affiliation
Institute of Human Nutrition and Food Science, Christian Albrechts University, Kiel, Germany.
pubmed:publicationType
Journal Article, Randomized Controlled Trial, Research Support, Non-U.S. Gov't