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Catechin and caffeine content of green tea dietary supplements and correlation with antioxidant capacity.
J Agric Food Chem. 2006 Mar 08; 54(5):1599-603.JA

Abstract

The health benefits associated with tea consumption have resulted in the wide inclusion of green tea extracts in botanical dietary supplements, which are widely consumed as adjuvants for complementary and alternative medicines. Tea contains polyphenols such as catechins or flavan-3-ols including epicatechin, epigallocatechin, epicatechin gallate, and epigallocatechin gallate (EGCG), as well as the alkaloid, caffeine. Polyphenols are antioxidants, and EGCG, due to its high levels, is widely accepted as the major antioxidant in green tea. Therefore, commercial green tea dietary supplements (GTDS) may be chemically standardized to EGCG levels and/or biologically standardized to antioxidant capacity. However, label claims on GTDS may not correlate with actual phytochemical content or antioxidant capacity nor provide information about the presence and levels of caffeine. In the current study, 19 commonly available GTDS were evaluated for catechin and caffeine content (using high-performance liquid chromatography) and for antioxidative activity [using trolox equivalent antioxidant capacity (TEAC) and oxygen radical antioxidant capacity (ORAC) assays]. Product labels varied in the information provided and were inconsistent with actual phytochemical contents. Only seven of the GTDS studied made label claims of caffeine content, 11 made claims of EGCG content, and five specified total polyphenol content. Caffeine, EGCG, and total polyphenol contents in the GTDS varied from 28 to 183, 12-143, and 14-36% tablet or capsule weight, respectively. TEAC and ORAC values for GTDS ranged from 187 to 15340 and from 166 to 13690 mumol Trolox/g for tablet or capsule, respectively. The antioxidant activities for GTDS determined by TEAC and ORAC were well-correlated with each other and with the total polyphenol content. Reliable labeling information and standardized manufacturing practices, based on both chemical standardization and biological assays, are recommended for the quality control of botanical dietary supplements.

Authors+Show Affiliations

Seeram NP
Center for Human Nutrition, David Geffen School of Medicine, University of California, Los Angeles, California 90095, USA. nseeram@mednet.ucla.edu
Henning SM
No affiliation info available
Niu Y
No affiliation info available
Lee R
No affiliation info available
Scheuller HS
No affiliation info available
Heber D
No affiliation info available

MeSH

AntioxidantsCaffeineCamellia sinensisCatechinChromansDietary SupplementsFlavonoidsPhenolsPlant LeavesPolyphenolsReactive Oxygen Species

Pub Type(s)

Journal Article

Language

eng

PubMed ID

16506807

Citation

Seeram, Navindra P., et al. "Catechin and Caffeine Content of Green Tea Dietary Supplements and Correlation With Antioxidant Capacity." Journal of Agricultural and Food Chemistry, vol. 54, no. 5, 2006, pp. 1599-603.
Seeram NP, Henning SM, Niu Y, et al. Catechin and caffeine content of green tea dietary supplements and correlation with antioxidant capacity. J Agric Food Chem. 2006;54(5):1599-603.
Seeram, N. P., Henning, S. M., Niu, Y., Lee, R., Scheuller, H. S., & Heber, D. (2006). Catechin and caffeine content of green tea dietary supplements and correlation with antioxidant capacity. Journal of Agricultural and Food Chemistry, 54(5), 1599-603.
Seeram NP, et al. Catechin and Caffeine Content of Green Tea Dietary Supplements and Correlation With Antioxidant Capacity. J Agric Food Chem. 2006 Mar 8;54(5):1599-603. PubMed PMID: 16506807.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Catechin and caffeine content of green tea dietary supplements and correlation with antioxidant capacity. AU - Seeram,Navindra P, AU - Henning,Susanne M, AU - Niu,Yantao, AU - Lee,Rupo, AU - Scheuller,H Samuel, AU - Heber,David, PY - 2006/3/2/pubmed PY - 2006/5/9/medline PY - 2006/3/2/entrez SP - 1599 EP - 603 JF - Journal of agricultural and food chemistry JO - J Agric Food Chem VL - 54 IS - 5 N2 - The health benefits associated with tea consumption have resulted in the wide inclusion of green tea extracts in botanical dietary supplements, which are widely consumed as adjuvants for complementary and alternative medicines. Tea contains polyphenols such as catechins or flavan-3-ols including epicatechin, epigallocatechin, epicatechin gallate, and epigallocatechin gallate (EGCG), as well as the alkaloid, caffeine. Polyphenols are antioxidants, and EGCG, due to its high levels, is widely accepted as the major antioxidant in green tea. Therefore, commercial green tea dietary supplements (GTDS) may be chemically standardized to EGCG levels and/or biologically standardized to antioxidant capacity. However, label claims on GTDS may not correlate with actual phytochemical content or antioxidant capacity nor provide information about the presence and levels of caffeine. In the current study, 19 commonly available GTDS were evaluated for catechin and caffeine content (using high-performance liquid chromatography) and for antioxidative activity [using trolox equivalent antioxidant capacity (TEAC) and oxygen radical antioxidant capacity (ORAC) assays]. Product labels varied in the information provided and were inconsistent with actual phytochemical contents. Only seven of the GTDS studied made label claims of caffeine content, 11 made claims of EGCG content, and five specified total polyphenol content. Caffeine, EGCG, and total polyphenol contents in the GTDS varied from 28 to 183, 12-143, and 14-36% tablet or capsule weight, respectively. TEAC and ORAC values for GTDS ranged from 187 to 15340 and from 166 to 13690 mumol Trolox/g for tablet or capsule, respectively. The antioxidant activities for GTDS determined by TEAC and ORAC were well-correlated with each other and with the total polyphenol content. Reliable labeling information and standardized manufacturing practices, based on both chemical standardization and biological assays, are recommended for the quality control of botanical dietary supplements. SN - 0021-8561 UR - https://www.unboundmedicine.com/medline/citation/16506807/Catechin_and_caffeine_content_of_green_tea_dietary_supplements_and_correlation_with_antioxidant_capacity_ DB - PRIME DP - Unbound Medicine ER -