Most antiandrogens inhibit DHT. DHT is connected to testosterone.  shows a beneficial effect on prostate cancer which can be caused by DHT. However, according to  garlic also increases testosterone.
What are the effects of garlic on Dihydrotestosterone (DHT) or 5α-dihydrotestosterone? Can it be used as an antiandrogen?
 Hsing AW, Chokkalingam AP, Gao YT, et al. Allium vegetables and risk of prostate cancer: A population-based study. Journal of the National Cancer Institute 2002; 94(21):1648–1651.
 Oi, Y; Imafuku, M; Shishido, C; Kominato, Y; Nishimura, S; Iwai, K (Aug 2001). "Garlic supplementation increases testicular testosterone and decreases plasma corticosterone in rats fed a high protein diet". The Journal of nutrition 131 (8): 2150–6.