Green tea (Camellia sinensis)
Blood and Urine Levels of Tea Catechins after Ingestion of Different Amounts of Green Tea by Human Volunteers
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The inhibitory activity of tea against tumorigenesis has been demonstrated in many animal models and has been suggested by some epidemiological studies. Such activity has generally been attributed to tea catechins. To understand the bioavailability of tea catechins in humans, we gave 18 individuals different amounts of green tea and measured the time-dependent plasma concentrations and urinary excretion of tea catechins. After taking 1.5, 3.0, and 4.5 g of decaffeinated green tea solids (dissolved in 500 ml of water), the maximum plasma concentration (Cmax) of (-)-epigallocatechin-3-gallate (EGCG) was 326 ng/ml, the Cmax of (-)-epigallocatechin (EGC) was 550 ng/ml, and the Cmax of (-)-epicatechin (EC) was 190 ng/ml. These Cmax values were observed at 1.4-2.4 h after ingestion of the tea preparation. When the dosage was increased from 1.5 to 3.0 g, the Cmax values increased 2.7-3.4-fold, but increasing the dose to 4.5 g did not increase the Cmax values significantly, which suggested a saturation phenomenon. The half-life of EGCG (5.0-5.5 h) seemed to be higher than the half-life of EGC or EC (2.5-3.4 h). EGC and EC, but not EGCG, were excreted in the urine. Over 90% of the total urinary EGC and EC was excreted within 8 h. When the tea dosage was increased, the amount of EGC and EC excretion seemed to increase, but a clear dose-response relationship was not observed. The present study provides basic pharmacokinetic parameters of green tea catechins in humans; these parameters may be used to estimate the levels of these compounds after drinking tea.
1 . Blood and urine levels of tea catechins after 3.0 g green tea extract administration (id=NPDI-F2VDuA)
In Vivo Pharmacokinetics Study
Results
| Sample | Compound measured | Value | Measurement | Study sequence | Additional information | N replicates |
|---|
Experimental Conditions
Single dosing
Healthy volunteers
6
blood samples: 0, 0.5, 2, 4, 8, and 24 h; urine samples: before the dose and during periods of 0-2, 2-6, 6-8, 8-24, and 24-48 h after the dose
Drug or Natural Product Administration
Oral
Beverage preparation was formulated by combining decaffeinated green tea extract solid 3.0 g with 45 g of sucrose, 7.5 g of coffee whitener (Borden 1-22007), and vanilla flavor (Tastmaker Lot SOS 5019). These beverage preparations were reconstituted in 500 mL of hot water.
3.0 g decaffeinated green tea extract
Fasted
Decaffeinated green tea extract was administered after an overnight fast
Single dose
not available
2 . Blood and urine levels of tea catechins after 4.5 g green tea extract administration (id=NPDI-kZAc2A)
In Vivo Pharmacokinetics Study
Results
| Sample | Compound measured | Value | Measurement | Study sequence | Additional information | N replicates |
|---|
Experimental Conditions
Single dosing
Healthy volunteers
6
The subjects refrained from drinking tea for 2 days before the experiment.
blood samples: 0, 0.5, 2, 4, 8, and 24 h; urine samples: before the dose and during periods of 0-2, 2-6, 6-8, 8-24, and 24-48 h after the dose
Drug or Natural Product Administration
Oral
Beverage preparation was formulated by combining decaffeinated green tea extract solid 4.5 g with 45 g of sucrose, 7.5 g of coffee whitener (Borden 1-22007), and vanilla flavor (Tastmaker Lot SOS 5019). These beverage preparations were reconstituted in 500 mL of hot water.
4.5 g decaffeinated green tea extract
Fasted
Decaffeinated green tea extract was administered after an overnight fast
Single dose
not available
3 . Blood and urine levels of tea catechins after 1.5 g green tea extract administration (id=NPDI-ZpUpLQ)
In Vivo Pharmacokinetics Study
Results
| Sample | Compound measured | Value | Measurement | Study sequence | Additional information | N replicates |
|---|
Experimental Conditions
Single dosing
Healthy volunteers
6
The subjects refrained from drinking tea for 2 days before the experiment.
blood samples: 0, 0.5, 2, 4, 8, and 24 h; urine samples: before the dose and during periods of 0-2, 2-6, 6-8, 8-24, and 24-48 h after the dose
Drug or Natural Product Administration
Oral
Beverage preparation was formulated by combining decaffeinated green tea extract solid 1.5 g with 45 g of sucrose, 7.5 g of coffee whitener (Borden 1-22007), and vanilla flavor (Tastmaker Lot SOS 5019). These beverage preparations were reconstituted in 500 mL of hot water.
1.5 g decaffeinated green tea extract
Fasted
Decaffeinated green tea extract was administered after an overnight fast
Single dose
not available