Black Tea Brew Research Articles

Effects of different brewing conditions on acrylamide levels in Turkish black tea and health risk assessment

In this study, the effects of different brewing parameters (brewing method, teapot spout shape, brewing time, brewing water temperature) on acrylamide levels in black tea were investigated. Then, the level of acrylamide exposure from black tea consumption was evaluated in terms of carcinogenic and non-carcinogenic health risks. The average acrylamide level of all black tea samples brewed with 24 different methods was 53.2±17.1 µg/L. There was no significant difference in acrylamide levels (median) between brewing parameters except for the brewing water temperature value (p < 0.01). Individuals aged 15 years and over living in Türkiye were found to have an acrylamide exposure level in the range of 0.06−0.27 µg/kg bw/day. Consumption of brewed black tea according to different brewing parameters in light, normal and over-brewed forms was found to be safe in terms of non-carcinogenic health risks. However, acrylamide exposure levels indicate the presence of potential and significant health risks in terms of carcinogenic risks considering similar consumption patterns. When all the data are evaluated together, in order to reduce the acrylamide exposure level and potential health risks of acrylamide, black tea should be brewed with water at 95 ℃ and over-brewed tea consumption should be avoided.

The levels of heavy metal, acrylamide, nitrate, nitrite, N-nitrosamine compounds in brewed black tea and health risk assessment: Türkiye

The levels of heavy metal, acrylamide, nitrate, nitrite, N-nitrosamine compounds in brewed black tea and health risk assessment: Türkiye

Impact of Grape Seed Powder and Black Tea Brew on Lipid Digestion-An In Vitro Co-Digestion Study with Real Foods.

Effects of two foods with bioactive constituents (black tea brew, BTB and grape seed powder, GSP) on lipid digestibility was studied. Lipolysis inhibitory effect of these foods was examined using two test foods (cream and baked beef) with highly different fatty acid (FA) composition. Digestion simulations were performed either using both gastric and pancreatic lipase, or only with pancreatic lipase according to the Infogest protocol. Lipid digestibility was assessed based on the bioaccessible FAs. Results showed the triacylglycerols containing short- and medium-chain FAs (SCFA and MCFA) are non-preferred substrates for pancreatic lipase; however, this is not characteristic for GL. Our findings suggest that both GSP and BTB primarily affect the lipolysis of SCFAs and MCFAs, because the dispreference of pancreatic lipase towards these substrates was further enhanced as a result of co-digestion. Interestingly, GSP and BTB similarly resulted in significant decrease in lipolysis for cream (containing milk fat having a diverse FA profile), whereas they were ineffective in influencing the digestion of beef fat, having simpler FA profile. It highlights that the characteristics of the dietary fat source of a meal can be a key determinant on the observed extent of lipolysis when co-digested with foods with bioactive constituents.

Effect of brewing method on quality parameters and antioxidant capacity of black tea

Introduction: The traditional method for brewing tea in Turkey involves use of a two-vessel apparatus known as a “caydanlik.” The caydanlik allows for tea to be brewed for a longer time than typical brewing methods and involves introducing boiling water to tea leaves and steeping them in a teapot as the temperature declines over 15 minutes. In comparison, the typical tea brewing method used in other parts of the world involves steeping tea leaves in a single vessel teapot for 5 minutes. This study evaluated the effects of these two methods of brewing using two brands of tea. Results: Results of this experiment indicate that use of the caydanlik and the accompanying longer brewing time significantly changed key quality parameters and increased the antioxidant capacity of the brewed black tea beverage. Use of the caydanlik method resulted in significantly higher (P &lt; 0.05) theaflavins, thearubigins, theabrownins, and total polyphenols in the resultant tea than in tea brewed in a traditional teapot. Additionally, analysis of color values of the brewed tea indicated the L and b-values were significantly (P &lt; 0.05) lower in the caydanlik brewed tea while a and hue values were significantly higher (P &lt; 0.05). However, chroma values were not significantly different (P &lt; 0.05) between the two methods. Conclusions: In addition to influencing color, flavor and aroma, the brewing method also influenced the functional properties of prepared black tea. Use of the traditional two-vessel caydanlik for tea preparation increased concentrations of beneficial functional components in the tea.Keywords: Black tea, Caydanlik, Brewing, Camelia sinensis, ORAC, Total Phenolic Content

Investigation on the production of bioethanol from black tea waste biomass in the seawater-based system

The present study is aimed to utilize the seawater-based system for the production of bioethanol from black tea waste generated after the first brewing to reduce the consumption of freshwater in bioethanol industries. Two yeast isolates (Zygosaccharomyces bailii MTCC 8177 and Brettanomyces claussenii MTCC 7801) from kombucha black tea were evaluated for the ethanol production due to their growing capability in black tea brew as well as in seawater. The results revealed that the boiling process releases higher fermentable sugars from black tea waste than the other pretreatment methods studied. Among the two yeasts (Zygosaccharomyces bailii and Brettanomyces claussenii) studied for bioethanol production in the seawater-based medium, immobilized cells of Z. bailii had six-fold greater yield than the free cells. In the case of B. claussenii cells, there was no significant difference in ethanol yield between the free and immobilized cells on glucose fermentation.

Modelling and simulation of a moving interface problem: freeze drying of black tea extract

The moving interface separates the material that is subjected to the freeze drying process as dried and frozen. Therefore, the accurate modeling the moving interface reduces the process time and energy consumption by improving the heat and mass transfer predictions during the process. To describe the dynamic behavior of the drying stages of the freeze-drying, a case study of brewed black tea extract in storage trays including moving interface was modeled that the heat and mass transfer equations were solved using orthogonal collocation method based on Jacobian polynomial approximation. Transport parameters and physical properties describing the freeze drying of black tea extract were evaluated by fitting the experimental data using Levenberg–Marquardt algorithm. Experimental results showed good agreement with the theoretical predictions.

In vitro anti-hyaluronidase activity of Sri Lankan low grown orthodox orange pekoe grade black tea (Camellia sinensis L.)

ABSTRACT Objective To access the anti-hyaluronidase activity of Sri Lankan low grown orthodox orange pekoe (OP) grade black tea with a view to develop an anti-aging skin formulation. Methods Five concentrations (0.125, 0.250, 0.500, 1.000 and 2.000 mg/mL) of black tea brew (BTB) were made using a freeze dried sample of Sri Lankan low grown orthodox OP grade black tea which was prepared according to international organization for standardization specification. Epigallocatechin gallate (EGCG) was used as the reference agent (concentrations tested: 0.012, 0.025, 0.050, 0.100 and 0.200 mg/mL). Anti-hyaluronidase activity of BTB and EGCG in vitro were ascertained spectrometrically using hyaluronic acid (from rooster comb) and bovine testicular hyaluronidase. Results The results revealed that BTB had moderate [IC 50 =(1.09±0.12) mg/mL] and dose dependent ( r 2 =0.94) anti-hyaluronidase activity. EGCG also exhibited dose dependent ( r 2 =0.93, P 50 =(0.09±0.00) mg/mL] to BTB. Conclusions Sri Lankan low grown orthodox OP grade black tea has promising anti-hyaluronidase activity in vitro and has the potential to be used as an anti-aging cosmaceutical. In addition, it may prove useful as a beverage in the management of allergy, some joint diseases and envenomation.

Minerals and trace elements in traditional foods of rural areas of Lhasa Prefecture, Tibet Autonomous Region (P.R. China)

Traditional foods play a major role in the diet of rural people living in the Tibet Autonomous Region of the People's Republic of China. Because these foods are mainly derived from local agriculture as well as artisanal production, their mineral composition may show significant discrepancies when compared with food composition data. This study aims at providing relevant data on the mineral composition of the main Tibetan foods. Sixteen different foodstuffs were sampled, including water, concentrated brewed black tea, chang, tsampa, wheat flour, dried cheese, dried yak meat, dried mutton, blood sausage, dried wild peaches, dried Chinese radish, and dried nettles. They were analyzed by inductively coupled plasma mass spectrometry (ICP-MS) for 19 minerals: Na, K, P, Ca, Mg, Fe, Zn, Mn, Cu, Ni, Se, Mo, Al, As, Cr, Co, Cd, Pb, and V. The validity of the results was ensured by the use of standard reference materials. A statistical comparison of the mean mineral contents of the analyzed foods against food composition data from the China Food Composition (CFC) table was carried out. It revealed significant discrepancies, emphasizing the importance of food analysis for nutritional assessment in Tibet autonomous region. To the best of our knowledge, the mineral compositions of some traditional Tibetan foods are here reported for the first time.

&lt;i&gt;In vitro&lt;/i&gt; Antiglycation and Cross-Link Breaking Activities of Sri Lankan Low-Grown Orthodox Orange Pekoe Grade Black Tea (&lt;i&gt;Camellia sinensis&lt;/i&gt; L)

Purpose: To investigate the antiglycation and cross-link breaking activities of Sri Lankan low-grown orthodox Orange Pekoe grade black tea (Camellia sinensis L) Methods: Five concentrations (6.25, 12.5, 25.0, 50.0 or 100.0 µg/ml) of Black tea brew (BTB) were made using Sri Lankan low-grown Orange Pekoe (O.P.) grade tea. Antiglycation and advanced glycation end products (AGEs) cross-link breaking activities of BTB as well as the antiglycation activity of rutin were determined in vitro on bovine serum albumin/glucose system using fluorescence spectroscopy. Results: BTB induced significant (p<0.05) antiglycation activity (IC50, 19.04 ± 5.18 µg/ml) and AGEs cross-link breaking activities (IC50, 82.89 ± 3.44 µg/ml). These effects were dose-dependent. Further, the antiglycation activity of BTB was comparable to rutin, a well-known antiglycation agent (IC50, 21.88 ± 2.82 µg/ml). Conclusion: These results show that Sri Lankan low-grown O.P. grade black tea possesses both antiglycation and AGEs cross-link breaking activities in vitro and thus provides scientific justification for the use of black tea in Sri Lankan indigenous medicine for the management of diabetic complications.

Oral diuretic activity of Sri Lankan low grown orange pekoe grade black tea (Camellia sinensis l.) In rats..

In Sri Lankan ethnomedicine, black tea is claimed to be a diuretic. However, the grade of the tea is not specified. The aim of this study was to investigate the diuretic potential of Sri Lankan low grown orthodox whole leaf grade black tea ( Camellia sinensis (L) O. Kuntz ; Family: Theaceae) using Orange Pekoe (O.P.) grade tea. Different doses of black tea brew (BTB) of O.P. grade tea [111 mg/kg (equivalent to 0.75 cups, N=7), 223 mg/kg (equivalent to 1.5 cups, N= 15), 446 mg/kg (equivalent to 3 cups, N=15) and 1339 mg/kg (equivalent to 9 cups, N=12)] or water (control, N=16) or Furosemide (reference drug, N=15) were orally administered to previously starved (18h) but subsequently hydrated (15 ml of isotonic saline) rats and their cumulative urine output was monitored at hourly intervals for 6h. The results showed moderate (compared to Furosemide), dose dependent diuretic activity. The onset of the diuretic activity was very rapid (within 1h) with an equally rapid peak dieresis (1-2h), but with a short duration of action (up to 2h). EC 50 value for the diuretic action was 509.18 mg/kg. The diuretic action was accompanied with significant (P<0.05) increase in urinary Na + (Natiuresis), K + (Kaliuresis), pH, glomerular filtration rate (GFR) (in terms of creatinine clearance), aldosterone secretion index, thiazide diuretic index, intra and extra cellular pH regulatory index and urinary alkali index, whilst the carbonic anhydrase inhibition index was significantly reduced. In contrast, urinary Cl - , and HCO 3 - levels, total dissolved solids, conductivity, density, and specific gravity remained unaltered. Overall, the results suggest that, Sri Lankan low grown O.P. grade black tea has moderate diuretic activity mediated via multiple mechanisms.

Sri Lankan orange pekoe grade black tea impairs anxiety

There is an unmet need for the development of new herbal pharmaceuticals as anxiolytics. In this context, the present study, investigated the anxiolytic potential of warm black tea brew/ infusion (BTB) of Sri Lankan low grown orthodox Orange Pekoe (O.P.) grade tea made from Camellia sinensis (L) O. Kruntz (Theaceae). This was tested in rats using three models of anxiety (hole-board, neophobic suppression of eating and drinking tests). Different doses [223 mg/kg (equivalent to 1.5 cups), 446 mg/kg (equivalent to 3 cups) and 1339 mg/kg (equivalent to 9 cups)] or water was orally administered to rats (N = 6-10/group) and anxiolytic effects were determined after 1h. The results showed that BTB possesses dose-dependent anxiolytic action with quick onset (1h). This anxiolytic action of BTB was not accompanied with undesirable side effects: muscle relaxation, motor in co-ordination or sedation. In addition, BTB produced no overt signs of toxicity. BTB induced significant increase in the number of entries, time spent in open arms, % open arm entries and % time on open arms and reduced the time spent in closed arms when tested in elevated plus maze model. This suggest that main mode of anxiolytic action of BTB is GABAergic. It is also suggested that, serotoninergic and dopaminergic mechanisms also play a part in mediating anxiolytic action. It is concluded that, O.P. grade Sri Lankan black tea has oral anxiolytic action as claimed in Sri Lankan traditional medicine and consumption of at least 3 cups of BTB may be useful to impair ‘day to day’ anxiety.

A natural theaflavins preparation inhibits HIV-1 infection by targeting the entry step: Potential applications for preventing HIV-1 infection

Theaflavins are the major components of tea polyphenols in brewed black tea. We previously reported that theaflavin derivatives, such as TF3, inhibited HIV-1 entry by targeting gp41. However, it is difficult to purify the individual theaflavins and the purified compounds are highly unstable. To develop theaflavins as affordable anti-HIV-1 microbide for preventing HIV sexual transmission, we intended to use an economic natural preparation containing 90% of theaflavins (TFmix). Its antiviral activity against HIV-1 strains was evaluated in vitro using p24 production and luciferase assays. The mechanism by which TFmix inhibits HIV-1 infection was investigated using time-of-addition, cell-cell fusion and biophysical assays. The data suggested TFmix exhibited potent anti-HIV-1 activity on lab-adapted and primary HIV-1 strains with IC 50 less than 1.20 μM. It also effectively inhibited infection by T-20 resistant HIV-1 strains. The mechanism studies suggest that TFmix mainly inhibit the HIV-1 entry by targeting gp41 since it is effective in inhibiting gp41 six-helix bundle (6-HB) formation and HIV-1 envelope protein-mediated cell-cell fusion. TFmix could also inhibit HIV-1 reverse transcriptase (RT) activity, but the IC 50 is about 8-fold higher than that for inhibiting gp41 6-HB formation, suggesting RT is not a major target for TFmix. In conclusion, TFmix is an economic natural product preparation containing high content of theaflavins with potent anti-HIV-1 activity by targeting the viral entry step through the disruption of gp41 6-HB core structure. It has a potential to be developed as a safe and affordable topical microbicide for preventing sexual transmission of HIV.

Effect of Brewed Black Tea as Adjust Treatment in Severity of Infants' Conjunctivitis

Material & Methods: This was a randomized clinical trial study in the Pediatric Clinic of Amir Kabir Hospital in Arak, Iran. A total of 110 infants were randomized into 2 treatment groups who received either brewed black tea add ophthalmic erythromycin ointment 1% with sulfastamid drop 10% (group A)TDS or just antibiotics (group B) for 7 days. In group A, before used of antibiotics sticky eyelids were wiped with sterile cotton of brewed black tea and in control group just antibiotics were applied. Severity of conjunctivitis at first, 3th and 7th days during treatment and duration of disease were determined. Results: At first day of prescribing strategies, group A severity of infants' conjunctivitis were mild in12/7 %( 7), moderate 32/7 %( 18) and sever 54/5 %( 30). In just antibiotics were 18/2 %( 10), 30/9%(17), 50/9 %( 28) respectively. Difference wasn't significant. At 3rd day, in group A 74/5 %( 41) of infants were cured, in 25/5%( 14), severity were mild. In control group, 9/1 %( 5) cured, mild were 21/8 (12), moderate 47/3 %( 26) and sever 21/8 %( 12). Differences was significant (P=0/001). At 7th days, in group A 100 %( 55), in just antibiotics 34/5 %( 19) were cured. Mild severity of conjunctivitis were 45/5 %( 25) and moderate were 20 %( 11), in control group. Conclusion: Brewed black tea adds antibiotics reduced severity of infants' conjunctivitis and duration of treatment. It seems it is safe; effectiveness, accessible and cost benefit for adjust treatment of this disease.

Effects of Sri Lankan Black Tea (Camellia sinensis L.) on Pregnancy of Rats

The aim of this study was to demonstrate the potential effects of black tea brew of Camellia sinensis using Sri Lankan high grown dust grade no. 1 tea on pregnancy outcome of rats when exposed during early (days 1-7), mid (days 8-14) and late (days 15-21) pregnancy of rats. Different doses of black tea brew (mg/ml/day) was orally administered daily during this period to separate groups of rats (n = 6/group): 84 (equivalent to 1.5 cups), 167 (3 cups), 501 (9 cups), and 1336 (24 cups). The results showed that black tea brew did not significantly (P > 0.05) change the pregnancy outcome (in terms of quantal pregnancy, number of uterine implants, number of viable implants, implantation index, pre-implantation loss, post-implantation loss, gestation index, number of pups born, litter index, live birth index and viability index) and pre- (in terms of length of the implants/foetus, gestation length, cranial length, cranial diameter and tail length of pups) and postnatal (in terms of time taken to open eyes, eruption of incisors and appearance of fur) development. Furthermore, black tea brew did not induce gross morphological birth abnormalities. If the results are applicable to women, it is concluded that even heavy consumption of black tea brew during pregnancy may not be harmful for pregnancy outcome.

Gastroprotective activity of Camellia sinensis black tea brew in rats

This study examined the gastroprotective potential of a black tea brew (BTB) of Camellia sinensis Linn. O. Kuntze (Theaceae) using Sri Lankan high grown Dust grade No: 1 tea in a rat ethanol-induced gastric lesion model. Three oral doses of BTB (84, 167, or 501 mg/mL) were used in evaluation of the gastroprotective activity. The results showed a strong dose dependent and significant (p < 0.05) gastroprotective activity (in terms of number, length, and area of hemorrhagic lesions). The gastroprotective activity of BTB was superior to that of the reference drug cimetidine. The high dose of BTB (only dose tested) also offered gastroprotection in rat indomethacin- and serotonin-induced gastric lesion models. Intraperitoneal treatment of BTB and oral treatment of BTB following decaffeination suppressed its gastroprotective potential. However, indomethacin pretreatment did not reduce the gastroprotective potential of BTB in the ethanol-induced gastric lesion model. BTB also increased the gastric mucus content (by Alcian blue test), thickness of the gastric mucus layer (by histopathology), pH of the gastric contents, and possibly the gastric mucosal blood flow, and reduced the gastric acid output of the stomach. BTB also had antihistamine (by wheal test) and antioxidant activity (by the DPPH method) and impaired the gastric transit (by charcoal plug test). It is concluded that BTB of C. sinensis possesses strong oral gastroprotective action, which is mediated via multiple mechanisms. The results also justify the claim made by Sri Lankan traditional practitioners that BTB of C. sinensis has gastroprotective action.

Effect of black tea brew of Camellia sinensis on sexual competence of male rats

Aim In Sri Lankan traditional medicine black tea brew (BTB) of Camellia sinensis (L.) O. Kuntze (Theaceae) is claimed to have male sexual stimulant activity. As this claim is not scientifically tested and proven, this study was undertaken to evaluate the effects of BTB on male sexual competence. Material and methods Different doses of BTB made from Sri Lankan high grown dust grade no 1 tea (84, 167 and 501 mg/ml) or water were orally administered to separate groups of rats ( n = 9 per group) and 3 h later their sexual behaviour were monitored (for 15 min) using receptive females. Results The overall results showed that BTB possesses marked aphrodisiac activity (in terms of prolongation of latency of ejaculation shortening of mount- and intromission latencies and elevation of serum testosterone level). The aphrodisiac action had a rapid onset and appears to be mediated via inhibition of anxiety and elevation of serum testosterone level. Further, this aphrodisiac action was not associated with impairment of other sexual parameters like libido, sexual motivation, sexual arousal, sexual vigour or penile erection. BTB was also nontoxic (in terms of overt signs, liver and renal toxicity). Conclusions It is concluded that BTB can function as a quick acting, safe, oral aphrodisiac which may also be useful in certain forms of sexual inadequacies such as premature ejaculation and impaired libido and other sexual functions.

Influence of milk and sugar on antioxidant potential of black tea

Black tea is often consumed with milk and sugar. It is still unknown with certainty whether addition of milk and (or) sugar affects its antioxidant activity. The present study is aimed to investigate the effect on antioxidant and radical scavenging activities of black tea on addition of milk and sugar. Four types of black tea brew samples are prepared, viz., plain black tea (B), black tea with sugar (BS), black tea with milk (BM) and black tea with milk and sugar (BMS). The freeze-dried solids of all the brew samples are evaluated for their biological activities. The radical scavenging and antioxidant activities are estimated using the 1,1-diphenyl-2-picrylhydrazyl (DPPH) and β-carotene-linoleic acid model systems, respectively. It is observed that radical scavenging activity of B was highest followed by BS and BMS. BM shows lowest activity. The antioxidant activity of black tea enhances and stabilizes with milk or sugar. The total polyphenol content is also determined and found to be higher in black tea sample compared to other samples. Both activities are compared with that of butylated hydroxy anisole (BHA) as a standard antioxidant and found to be less in all cases.

Mineral analysis of ten types of commercially available tea

Many herbal infusions (teas) are being studied for their impact on health, yet little research has examined their mineral content. The purpose of this study was to determine the mineral content of 10 commercially available dry teas and the infusions produced from them. Herbal infusions studied included commercial blends of peppermint, Echinacea, red clover, Siberian ginseng, dandelion, red raspberry leaf, blueberry leaf and green tea. None of the infusions was a good source of Ca, Mg, P, K, Na, Cu, Fe, Mn, or Zn in a single serving. Extraction rates (excluding Siberian ginseng) were for K (71%), P (43%), Mg (38%), Na (34%), Ca (18%), Cu (33%), Fe (6%), Mn (24%) and Zn (35%). K levels were high enough that 3.5 cups of dandelion infusion and 4.5 cups of Echinacea infusion provide a good source (10% Daily Value). By comparison, standard reference levels for both brewed black tea and coffee indicate these beverages contain several times as much K as dandelion and Echinacea infusions. These data suggest that these infusions will not interfere with low Na diets.

Black Tea Represents a Major Source of Dietary Phenolics Among Regular Tea Drinkers

The phenolic composition and antioxidant activities [TEAC, ORAC, FRAP] of consumer brews (1 tea bag in 230 ml for 1 min) of seven different brands of black tea from the British market were investigated. The main phenolic compounds identified were epigallocatechin gallate, four theaflavins, as well as epicatechin gallate, theogallin (tentative assignment), quercetin-3-rutinoside and 4-caffeoyl quinic acid. Thearubigins represented an estimated 75-82% of the total phenolics. Further, polyphenol fractions were in decreasing order theaflavins, flavan-3-ols, flavonols, gallic acids and hydroxycinnamates. On average, a cup of a consumer brew of black tea is providing polyphenols at the level of 262 mg GAE/serving, of which 65 mg were assigned to individual polyphenols. The antioxidant activity of black tea preparations is higher than that of most reported dietary agents on a daily basis. Correlations were observed between the antioxidant activities and the sum of all quantified polyphenols by HPLC analysis as well as with the total phenolics. Treatment of the black tea brew with simulated gastric juice resulted in a significant increase of the identified theaflavins implying a partial cleavage of thearubigins in the environment of the gastric lumen. Therefore, black tea can be considered to be a rich source of polyphenols and/or antioxidants.

Pharmacokinetics of Gallic Acid and Its Relative Bioavailability from Tea in Healthy Humans

Gallic acid (GA), a food component that is especially abundant in tea, is an antimutagenic, anticarcinogenic and anti-inflammatory agent. We conducted a study using acidum gallicum tablets that contained 10% GA and 90% glucose and a black tea brew that contained 93% of its GA in free form to determine the pharmacokinetics and relative bioavailability of GA in healthy humans. After the administration of a single oral dose of acidum gallicum tablets or tea (each containing 0.3 mmol GA) to 10 volunteers, plasma and urine samples were collected over various time intervals. Concentrations of GA and its metabolite, 4-O-methylgallic acid (4OMGA), were determined, and the pharmacokinetic parameters were calculated. GA from both the tablets and tea was rapidly absorbed and eliminated with mean half-lives of 1.19 +/- 0.07 and 1.06 +/- 0.06 h and mean maximum concentrations of 1.83 +/- 0.16 and 2.09 +/- 0.22 micromol/L (plasma), respectively. After oral administration of the tablets and black tea, 36.4 +/- 4.5 and 39.6 +/- 5.1% of the GA dose were extracted in urine as GA and 4OMGA, respectively. The relative bioavailability of GA from tea compared with that from the tablets was 1.06 +/- 0.26, showing that GA is as available from drinking tea as it is from swallowing tablets of GA.