Vitex agnus-castus (VAC) — commonly called just Vitex, but also called Chaste Tree, Chasteberry, or Monk's Pepper — is a native of the Mediterranean region. Refer to Vitex for other species in the genus.
Vitex, also a traditional plant in Africa, is a little-known fruit plant that has potential to improve nutrition, boost food security, foster rural development and support sustainable landcare.
The leaves and tender stem growth of the upper 10 cm (4 inches), along with the flowers and ripening seeds, are harvested for medicinal purposes. The berries are harvested by gently rubbing the berries loose from the stem. The leaves, flowers, and/or berries may be consumed as a decoction, traditional tincture, cider vinegar tincture, syrup, elixir, or simply eaten straight off the plant as a medicinal food.
The berries are considered a tonic herb for both the male and female reproductive systems. The leaves are believed to have the same effect but to a lesser degree.
This plant is commonly called monk's pepper because it was originally used as anti-libido medicine by monks to aid their attempts to remain celibate. It is believed to be an anaphrodisiac, hence the name chaste tree.
Clinical studies have shown its beneficial effects in the management of premenstrual stress syndrome (PMS). and infertility. The use of extracts of the plant is recommended in Germany.
Its mechanism of action is not well known. A study has found that treatment with higher doses of Vitex Agnus-castus caused a slight "reduction" of prolactin levels, whereas lower doses caused a slight "increase" as compared to doses of "placebo". A decrease of prolactin will influence levels of follicle-stimulating hormone (FSH) and estrogen in women; and testosterone in men.
It is used in some supplements for male bodybuilders as a secondary component because of its effects on testosterone levels.