Green Tea Dietary Supplements Research Articles

Content of Caffeine and Catechins Measured in Multi-ingredient Dietary Supplements Containing Green Tea: Association with Label Claims and Proprietary Blends

Abstract Objectives Multi-ingredient dietary supplements (DSs) containing green tea (GT) were analyzed for their phytochemical content (seven catechins and caffeine) as part of a Dietary Supplement Ingredient Database project. The label information required by FDA is the weight of the GT extract or leaf powder, unless it is part of a proprietary blend (only the blend weight needed). Any information about the concentration of GT phytochemicals is voluntary. We assessed the accuracy of the mandatory and voluntary portions of labels and the effect of proprietary blends on the phytochemical content. Methods Two lots of 37 GT DSs, estimated to contain ≥40 mg/serving of GT, were purchased in a variety of market channels. Samples were sent for analysis to two experienced laboratories. Means and standard errors for the analytically measured content of epigallocatechin gallate (EGCG; the most prevalent catechin), the summed content of the catechins (total catechins, TC), and caffeine were derived for each DS and compared to label information. Results The measured content of EGCG, TC, and caffeine showed wide ranges (0 (not detected) - 442, 0–711, and 0–982 mg/day, respectively). DSs with concentration claims for EGCG and caffeine (32% and 43%, respectively) had higher content per serving compared to DSs without such information (P < 0.05). Most DSs with voluntary claims for EGCG, TC or caffeine content (74%) had actual content within ± 20% of the labels. The catechin content was not significantly different in DSs with GT amounts listed on the label (n = 20) compared with DSs listing GT as part of a proprietary blend (n = 17). However, DSs with GT in a blend had significantly more caffeine than those with a label claim for GT amount (means (SE) per day 197 (63) vs. 49 (18), respectively; P = 0.037). Conclusions The actual content of GT constituents such as EGCG, TC and caffeine in multi-ingredient GT DSs varied depending on the labeling formats. DSs with a voluntary label claim for EGCG had significantly higher EGCG content than those with only the required claims. DSs with GT listed as a part of a blend had significantly higher levels of caffeine than products with labeled GT amounts. More complete label information would be beneficial both for consumers and for researchers who track phytochemical intakes and their associations with health outcomes. Funding Sources NIH/ODS and USDA/ARS.

Disintegration and Dissolution Testing of Green Tea Dietary Supplements: Application and Evaluation of United States Pharmacopeial Standards

Approved performance quality tests are lacking in the United States Pharmacopeia (USP) for dietary supplements (DSs) containing green tea extracts. We evaluated the applicability of USP <2040 > general chapter protocols for disintegration and dissolution testing of botanicals to GT DSs. Of 28 single-ingredient GT DSs tested in 2 to 4 lots, 9 (32.1%) always passed the disintegration test, 8 (28.6%) always failed, and 11 (39.3%) showed inconsistent results. Of 34 multi-ingredient DSs tested in 2 lots, 21 (61.8%) passed and 8 (23.5%) failed in both lots, and 5 (14.7%) exhibited inconsistent performance. When stronger destructive forces were applied (disk added), all of the capsules that had failed initially, but not the tablets, passed. In dissolution testing, for the release of epigallocatechin-3-gallate (EGCG), only 6 of 20 single-ingredient DSs passed. Unexpectedly, with the addition of pepsin (prescribed by USP), only one additional DS passed. These results raise concerns that EGCG was not released properly from GT DS dosage forms. However, the general USP protocols may be inadequate for this botanical. More biorelevant destructive forces may be needed to break down capsules and tablets strengthened by the EGCG’s interaction with shell material and to overcome the inhibition of digestive enzymes by EGCG.

Measurement of Epigallocatechin Gallate (EGCG) and Caffeine Content of 32 Green Tea Dietary Supplements for the Dietary Supplement Ingredient Database (DSID)

According to the 2007–10 NHANES, 7.5% of the US population reports botanical dietary supplement (DS) use. The DSID provides analytically‐derived estimates of the ingredient contents of DS. Commonly consumed and frequently studied, green tea (GT) DS were chosen as the first botanical DS for the DSID botanical initiative. The most abundant GT constituents are the catechins, especially EGCG, and caffeine. Our goal was to evaluate methods of analysis for individual catechins, caffeine and other GT constituents of interest, decipher patterns in constituent content labeling, and examine relationships between label claims and measured phytochemical constituent content.Current labeling regulations require information on the amount of each botanical or botanical extract present in a DS. Claims about the concentration of naturally occurring phytochemical constituents of the botanicals or botanical extracts in the products are not mandatory. For researchers to more accurately estimate phytochemical intake from DS, the content of these constituents should be measured.DS that contained GT as the only or primary botanical were selected for analysis in order to minimize interferences from sources of the same phytochemicals in non‐GT ingredients. Two lots of 32 DS purchased in various market channels and in a variety of forms (27 capsules, 2 liquids, 1 tablet, 1 softgel, 1 powder) were sent for analysis to 3 laboratories. Quality control results from all three laboratories showed good agreement with certified values for GT Standard Reference Materials®, indicating that methods employed by the laboratories can produce reliable and consistent data.As required, all 32 DS listed the weight of GT leaf/extract on the label, but a wide range (0.5–309.5 mg/serving) of EGCG content was found for the most common GT content claim (500 mg per serving, n=9). Eighteen of 32 DS voluntarily listed EGCG content on the label. Twelve products had only 1 listed source of EGCG, and amounts of EGCG in 9 of 12 were within ± 20% of label claim. The remaining 6 DS claimed an additional botanical source of EGCG but lacked information for its EGCG content. ANOVA indicated that the measured EGCG amount (mg/serving) in DS without EGCG label claims was significantly different from EGCG measured in DS with an EGCG claim on the label (for both single and two GT EGCG sources; 60 ± 53, 216 ± 146 and 141 ± 41, mean ± SD, respectively; p&lt;0.05). The measured amount of EGCG in the latter two DS groups was not significantly different (p&gt;0.05).The caffeine content (mg/serving) measured in DS without caffeine label claims (n=25) was lower than in DS with such claims (n=7) (means: 30 and 14, medians: 36 and 5, respectively; Kolmogorov‐Smirnov test, p = 0.02).Thus, different label formats for GT DS may differ in their predictive strength for analytical constituent content. Labels that provide only the amount of GT leaf or extract may not permit accurate estimates of GT phytochemical constituents and are thus less informative for phytochemical intake estimates from DS.Support or Funding InformationFunding: ARS/USDA &amp; ODS/NIH Y1CN501006

Characterization of the Major Components in Different Green Tea Dietary Supplements using HPLC and Multivariate Statistical Analysis

Aim Green tea dietary supplements are sold all over the world, and consumers are buying record amounts of green tea products every year. However, the qualities of the products are poorly controlled, which may not only varies the benefit but also hurt the costumer. The purpose of this paper is to compare the contents of the major components in different Green tea supplements. Main Methods A normalized extraction is used to extract green tea products. UPLC- MS/MS and co-elution with standard compounds were employed to identify the major components. An HPLC method is used to quantify the identified components in different supplements. PCA and HCA were used to evaluate the variability of these products. Key Findings The quality of green tea supplements was determined based on the recommended daily dose. Eallocatechin, epigallocatechin, caffeine, epicatechin, epigallocatechin-3-gallate, gallocatechin gallate, and epicatechin-3-gallate were identified as the major components in 12 different green tea supplements purchased from local store or internet. Quantitative analysis results showed that the contents of these components were highly variable across products. Hierarchical cluster analysis (HCA) and principal component analysis (PCA) analysis revealed the 12 products used in this study can be divided into four groups based on the contents of the major components per daily dose. Significance This study suggested that the quality of different green tea supplements are highly variable, which most likely could lead to variable biological effects. Standardization of green tea supplement is necessary to derive more consistent potential benefits.

Content Variation of Catechin Markers, Total Phenolics and Caffeine in Green Tea Dietary Supplements

ABSTRACTGreen tea (Camellia sinensis) preparations are among the top selling products in the United States dietary supplements market. Numerous manufacturers claim different levels of specific catechin markers in their products while many others use total phenolic concentration instead, or not at all. Limited quality control results have been published for green tea dietary supplements over the past seven years. Thus, the goal of this work was to correlate determined levels of phenolics, catechins, and caffeine with manufacturer label claims for selected dietary supplement products (26 total) purchased in the United States. The Folin-Ciocalteu (FC) method was used to determine the total phenolic content while reversed-phase (RP) HPLC was used to quantify the major catechins: epicatechin (EC), epigallocatechin (EGC), epicatechin gallate (ECG), epigallocatechin gallate (EGCG). The developed HPLC method was validated for accuracy and precision. It utilized a C8 column with gradient elution of acetonitrile in 0.1% aqueous formic acid over 11 min total run time. Peak detection was performed at 280 nm. Caffeine was also included in the HPLC method as another non-phenolic alkaloid marker commonly found in green tea. Both methods showed a good correlation between the content of catechins and polyphenolic compounds in the selected products. The ranges of total catechins and polyphenol concentrations were 3.8–70.2% and 3.6–95.8%, respectively, while that of caffeine was 0.8–11.2%. The selected products displayed a wide range of marker levels. A lack of conformity in disclosing the actual levels of marker compounds was also noticed in the labeling of many products.

A Non-targeted Approach to Chemical Discrimination Between Green Tea Dietary Supplements and Green Tea Leaves by HPLC/MS

Green tea-based dietary supplements (GTDSs) have gained popularity in the U.S. market in recent years. This study evaluated the phytochemical composition difference of GTDS in comparison with green tea leaves using an HPLC/MS fingerprinting technique coupled with chemometric analysis. Five components that are most responsible for class separation among samples were identified as (-) epicatechin gallate, strictinin, trigalloylglucose, quercetin-3-O-glucosyl-rhamnosylglucoside, and kaempferol-3-O-galactosyl-rhamnosylglucoside, according to the accurate mass measurements and MS/MS data. The similarity coefficients between the GTDSs in solid form with green tea were 0.55 to 0.91, while for the GTDSs in liquid form they were 0.12 to 0.89, which suggested that chemical composition variance across the GTDSs was significant. Flavonol aglycone concentrations were higher in GTDSs than in tea leaves, indicating the degradation of flavonol glycosides or the oxidation of catechin during the manufacturing and storage processes. In some GTDS samples, compounds were identified that were on the label. The results demonstrate the urgency of QC for GTDS products.

An LC-ESI/MS method for determining theanine in green tea dietary supplements

Theanine is the major amino acid present in Camellia sinensis or green tea. A method for determining theanine in its native state using liquid chromatography with positive-mode electrospray ionization mass spectrometric detection was developed. Quantitation of theanine was achieved using theanine-[(2)H(5)] as an internal standard. This approach was utilized on different green tea matrix materials that are commonly used as dietary supplements including powdered plant leaves, a powdered plant leaf extract, and an oral dosage form that contains green tea. The theanine response was linear over several orders of magnitude, and excellent measurement precision was obtained for all three materials using the developed method.

Hepatotoxicity of high oral dose (−)-epigallocatechin-3-gallate in mice

The tea polyphenol (−)-epigallocatechin-3-gallate (EGCG) has been studied for chronic disease preventive effects, and is marketed as part of many dietary supplements. However, case-reports have associated the use of green tea-based supplements with liver toxicity. We studied the hepatotoxic effects of high dose EGCG in male CF-1 mice. A single dose of EGCG (1500 mg/kg, i.g.) increased plasma alanine aminotransferase (ALT) by 138-fold and reduced survival by 85%. Once-daily dosing with EGCG increased hepatotoxic response. Plasma ALT levels were increased 184-fold following two once-daily doses of 750 mg/kg, i.g. EGCG. Moderate to severe hepatic necrosis was observed following treatment with EGCG. EGCG hepatotoxicity was associated with oxidative stress including increased hepatic lipid peroxidation (5-fold increase), plasma 8-isoprostane (9.5-fold increase) and increased hepatic metallothionein and γ-histone 2AX protein expression. EGCG also increased plasma interleukin-6 and monocyte chemoattractant protein-1. Our results indicate that higher bolus doses of EGCG are hepatotoxic to mice. Further studies on the dose-dependent hepatotoxic effects of EGCG and the underlying mechanisms are important given the increasing use of green tea dietary supplements, which may deliver much higher plasma and tissue concentrations of EGCG than tea beverages.

HPLC Analysis of Catechins, Theaflavins, and Alkaloids in Commercial Teas and Green Tea Dietary Supplements: Comparison of Water and 80% Ethanol/Water Extracts

ABSTRACT: To help meet the needs of consumers, producers of dietary tea supplements, and researchers for information on health‐promoting tea compounds, we compared the following conditions for the extraction of tea leaves and green tea‐containing dietary supplements: 80% ethanol/water at 60 °C for 15 min and boiled water for 5 min. The following 7 catechins, 4 theaflavins, and 3 alkaloids were separated in a 70‐min single HPLC analysis: (−)‐epigallocatechin, (−)‐catechin, (+)‐epicatechin, (−)‐epigallocatechin‐3‐gallate, (−)–gallocatechin‐3‐gallate, (−)‐epicatechin‐3‐gallate, (−)‐catechin‐3‐gallate, theaflavin, theaflavin‐3‐gallate, theaflavin‐3′‐gallate, theaflavin‐3,3′‐digallate, caffeine, theobromine, and theophylline. The following ranges of concentrations of flavonoids (catechins plus theaflavins) in the tea leaves extracted with 80% ethanol were observed (in mg/g): in 32 black teas, 19.8 to 115.1; in 24 green teas, 12.3 to 136.3; in 14 specialty teas, 4.9 to 118.5; in 7 herbal teas, 0 to 46.0. Total alkaloids in all teas ranged from 0 to 32.6 mg/g. Significantly greater amounts of flavonoids were extracted from the tea leaves with aqueous ethanol than with boiled water. Levels of tea catechins in 10 capsules sold as dietary supplements were about 50 to 75% lower than the amounts listed on the labels. Catechin content of 4 commercial green tea extracts ranged from 96 to 696 mg/g. The results make it possible to maximize the extraction of tea compounds to better relate the flavonoid and alkaloid content of teas and dietary tea supplements to their health‐promoting effects.

Catechin and Caffeine Content of Green Tea Dietary Supplements and Correlation with Antioxidant Capacity

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.