Swanson Premium-Full Spectrum Chasteberry Fruit, also known as Vitex agnus-castus, has a long history of use by women during their periods. If you re a woman who goes through the same battle every month, be prepared for more pain control. Research suggests that it has progesterone-like effects, which may explain its support for women s health. Because of this activity, Chasteberry is recommended for various PMS problems, including mood, body tenderness, and water balance.