Tags

Type your tag names separated by a space and hit enter

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.
J Physiol Pharmacol. 2009 Sep; 60(3):103-8.JP

Abstract

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.

Authors+Show Affiliations

Institute of Human Nutrition and Food Science, Christian Albrechts University, Kiel, Germany.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article
Randomized Controlled Trial
Research Support, Non-U.S. Gov't

Language

eng

PubMed ID

19826188

Citation

Augustin, K, et al. "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." Journal of Physiology and Pharmacology : an Official Journal of the Polish Physiological Society, vol. 60, no. 3, 2009, pp. 103-8.
Augustin K, Frank J, Augustin S, et al. 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. J Physiol Pharmacol. 2009;60(3):103-8.
Augustin, K., Frank, J., Augustin, S., Langguth, P., Ohrvik, V., Witthoft, C. M., Rimbach, G., & Wolffram, S. (2009). 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. Journal of Physiology and Pharmacology : an Official Journal of the Polish Physiological Society, 60(3), 103-8.
Augustin K, et al. 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. J Physiol Pharmacol. 2009;60(3):103-8. PubMed PMID: 19826188.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - 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. AU - Augustin,K, AU - Frank,J, AU - Augustin,S, AU - Langguth,P, AU - Ohrvik,V, AU - Witthoft,C M, AU - Rimbach,G, AU - Wolffram,S, PY - 2008/06/24/received PY - 2009/07/15/accepted PY - 2009/10/15/entrez PY - 2009/10/15/pubmed PY - 2010/3/31/medline SP - 103 EP - 8 JF - Journal of physiology and pharmacology : an official journal of the Polish Physiological Society JO - J. Physiol. Pharmacol. VL - 60 IS - 3 N2 - 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. SN - 1899-1505 UR - https://www.unboundmedicine.com/medline/citation/19826188/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_ L2 - http://www.jpp.krakow.pl/journal/archive/09_09/pdf/103_09_09_article.pdf DB - PRIME DP - Unbound Medicine ER -