Some herbal estrogen blockers include wild nettle root, chrysin, maca and grape seed, according to Healthline. These herbs work by blocking estrogen and increasing testosterone levels.
Grape seed extract blocks aromatase, the enzyme that converts androgen into estrogen, according to a study published in Cancer Research. The herb was effective in slowing tumor growth in breast cancer.
Chrysin similarly works as an aromatase inhibitor, according to Healthline. It is a compound occurring naturally in plants, such as passion flowers and geraniums. Some studies have reported reduced estrogen levels with chrysin treatments; however, no human studies have increased testosterone levels with the herb.