Table 9

Effect of oral administration of green tea, decaffeinated green tea, or caffeine on UVB-induced complete carcinogenesis

In experiment 1, female SKH-1 mice were treated with UVB (30 mJ/cm2) twice weekly for 40 weeks, and the animals were killed 4 weeks later. Water, tea leaf extracts (1.25 gm tea leaf/100 ml hot water; ∼4 mg tea solids/ml), and caffeine (0.36 mg/ml) were administered as the drinking fluid until the animals were sacrificed. Each value is from 24–30 mice. In experiment 2, female SKH-1 mice were treated with UVB (30 mJ/cm2) twice weekly for 45 weeks. Lyophilized teas (9 mg tea solids/ml) were administered as the drinking fluid. Each value is from 27–30 mice.

ExperimentTreatmentTea solids (mg/ml)Number of keratoacanthomas per mouseNumber of carcinomas per mouse
1Water5.75 ± 1.041.58 ± 0.32
Green tea4.02.21 ± 0.46a0.86 ± 0.23b
Decaf. green tea3.64.58 ± 0.641.66 ± 0.30
Caffeine0.361.81 ± 0.44a1.00 ± 0.20c
Decaf. green tea + caffeine4.02.53 ± 0.43a0.57 ± 0.12a
2Water0.89 ± 0.240.93 ± 0.28
Green tea9.00.29 ± 0.09a0.19 ± 0.09a
Decaf. green tea9.02.37 ± 0.46a1.44 ± 0.24c
  • Values ± SE that are statistically different from the corresponding water group are indicated. (Taken from Ref. 318 .)

  • a P < 0.01.

  • b P < 0.05.

  • c P < 0.10.