On the other hand, green tea did not reduce the serum level of DHT, but instead tended to increase it (P = 0.076) (Fig. 2Citation D), and we found that green tea treatment did not inhibit tumor growth (Fig. 1Citation A). Green tea contained more EGCG than black tea (Table 1)Citation , and studies have shown that EGCG inhibits the activity of 5{alpha}-reductase (38Citation ). These results derived from our animal model suggest that, although EGCG may be a potent antitumor agent in green tea and inhibit 5{alpha}-reducatase activity, green tea contains other constituents that may counteract EGCG’s antitumor activity, in part by counteracting its modulation of 5{alpha}-reducatase activity. Further research is required to identify these constituents and study their effects and/or their interactions with other components on prostate cancer. Our results demonstrate the importance of evaluating the benefit of whole tea products, rather than just isolated tea catechins or EGCG, on prostate cancer prevention because other tea constituents may play important roles.
Green tea combined with SPC reduced total testosterone and DHT levels (Fig. 2Citation A, B), suggesting that interactive modulation of androgen levels is one of the important mechanisms for the synergistic prevention of prostate cancer progression by the soy/green tea combination. This study supports the use of appropriate combinations of bioactive dietary agents, such as soy and tea, as effective nutritional regimens for prostate cancer prevention and treatment.