贞节树(Vitex agnus-castus) 来自贞节树的提取物，如果你是个补剂老手，你可能会知道贞节树传统上是一种“女性“补剂，因为它可以减轻经前综合症和其他月经失调的症状。贞节树的主要成分是牡荆甙（agnuside），它可以减少催乳素的产生。尽管催乳素被认为是一种雌性激素，象雌醇一样，但男性也含有一些。当你睡觉的时候，催乳素水平升高。大量的催乳素会减少睾酮产生。补充贞节树可以保证你的睾酮水平不会被阻止。
剂量：购买每份含200-400mg贞节树提取物的产品。睡前服用，连续服用4-6周，然后停4-6周，交替循环。

http://www.super-nutrition.net/ShowArticle.asp?ArticleID=457

google来的

Scientific studies
     One of the most cited studies of the pharmacological effects of Vitex was carried out by Haller at the University of Gottingen in the early 1960s. Female Guinea pigs were given Vitex tincture orally at normal to high dose for 90 days.³ At the end of this time the animals were examined for any changes in organ structure or weight. It was concluded that at normal doses Vitex clearly demonstrated a decrease of oestrogen effects and an increase of progesterone effects. This effect was mediated through the pituitary gland: Follicle Stimulating Hormone secretion was decreased and Lutenizing Hormone and Prolactin secretion were increased. Consistent with this hypothesis, corpus luteal development and glandular proliferation in breast tissue were enhanced and follicular development and uterine weight were slightly decreased.

http://www.positivehealth.com/permit/Articles/Herbal/atkin23.htm

看样子，可能有刺激pituitary gland（脑垂体）的作用，或许跟这个有关？