Anise does not directly raise your body’s estrogen levels, but it contains compounds that mimic estrogen by binding to the same receptors. This means anise acts like a weak form of estrogen in the body, which is why it has been used for centuries to address estrogen-related conditions like menstrual irregularities, menopausal symptoms, and low milk supply. The distinction matters: anise produces estrogen-like effects without necessarily changing the amount of estrogen circulating in your blood.
How Anise Mimics Estrogen
The key compound in anise is anethole, a molecule found in the plant’s essential oil. Anethole is classified as a phytoestrogen, meaning it’s a plant-derived substance whose shape closely resembles the human hormone estradiol. All phytoestrogens share a structural feature: two hydroxyl groups positioned about 10 angstroms apart, which is the same spacing found in estradiol. This allows them to dock with estrogen receptors in your cells and trigger some of the same biological responses that estrogen would.
In vitro testing using a human placenta model ranked anethole as one of the most estrogenic plant molecules tested. But early researchers noticed something interesting. Anethole itself may not be the strongest player. The actual heavy lifters appear to be dianethole and photoanethole, which are polymers (essentially larger molecules built from anethole units). These polymers seem to carry more potent estrogenic activity than anethole alone.
This estrogenic activity is far weaker than pharmaceutical estrogen or what your ovaries produce. Phytoestrogens generally bind to estrogen receptors with much less strength than your body’s own hormones, which is why they’re sometimes described as having a modulating effect rather than a powerful hormonal one.
What the Clinical Evidence Shows
The most direct clinical evidence comes from studies on menopausal hot flashes. In a trial of postmenopausal women taking anise capsules, hot flash frequency dropped from about 4.2 episodes before treatment to 1.06 episodes by the end of four weeks. Hot flash severity scores fell even more dramatically, from 56.2 down to 14.4 over the same period. Both changes were statistically significant. These results are consistent with what you’d expect from a compound acting on estrogen receptors, since hot flashes are driven by declining estrogen levels during menopause.
However, no published human trials have measured actual serum estrogen levels before and after anise supplementation. The evidence we have shows that anise produces effects that look like increased estrogen activity (fewer hot flashes, changes in milk production), but this likely reflects receptor-level activity rather than a true rise in circulating estrogen.
Anise and Breast Milk Production
Anise has a long history as a galactagogue, a substance believed to boost breast milk supply. Some clinical data supports a modest effect. In one trial, mothers of preterm infants who took 2 grams of dried anise three times daily for a week pumped more milk and spent more time expressing than mothers who received a placebo or no treatment. The difference in milk volume between groups grew larger with each passing day.
Interestingly, a separate trial using a tea blend containing anise (along with fennel, goat’s rue, and other herbs) found that while the tea group produced more milk, there was no difference in prolactin levels between groups at seven days. Prolactin is the primary hormone responsible for milk production, so the mechanism behind anise’s effect on lactation remains unclear. It may involve estrogen receptor activity in breast tissue rather than a straightforward hormonal increase.
Anise Seed vs. Star Anise
These are two completely different plants that happen to share a similar flavor compound. Anise seed comes from Pimpinella anisum, a flowering plant in the carrot family. Star anise comes from Illicium verum, an evergreen tree native to East Asia. Both contain anethole as their dominant flavor and aroma compound, which means both have estrogenic properties through the same mechanism. Fennel is a third plant in this group, also rich in anethole. If you’re concerned about estrogenic effects, the source of anethole matters less than the amount you’re consuming.
Who Should Be Cautious
Because anise acts like estrogen in the body, it poses a real concern for people with hormone-sensitive conditions. If you have a history of breast cancer, uterine cancer, ovarian cancer, endometriosis, or uterine fibroids, anise in supplement form could theoretically worsen these conditions by stimulating estrogen receptors in affected tissues.
The interaction with cancer treatment is worth particular attention. Both anise and star anise appear on cautionary lists for patients taking tamoxifen or aromatase inhibitors, two common breast cancer medications that work by blocking estrogen activity. Anise’s estrogen-mimicking effects could work against these drugs. The key caveat: this concern applies to concentrated doses like supplements and extracts, not the small amounts of anise found in food. A pinch of anise in your cookie recipe or a cup of anise tea is not the same as taking anise capsules daily.
For people taking birth control pills or hormone replacement therapy, anise supplements could theoretically add to the overall estrogenic load your body is processing, though this interaction hasn’t been studied directly in clinical trials.
The Practical Takeaway
Anise doesn’t increase the estrogen your body produces. What it does is introduce plant compounds that activate estrogen receptors, creating effects that resemble a mild boost in estrogen activity. For someone dealing with menopausal symptoms, this can be genuinely helpful. For someone with a hormone-sensitive condition, it’s a reason to avoid concentrated anise products. The amount in ordinary cooking and occasional tea drinking is generally considered too small to produce meaningful hormonal effects in either direction.