Aromatase is the bodily process of converting androgens, with the exception of dihydrotestosterone (DHT), into estrogens.
It so happens that aromatase enzymes occur in tissue where Estrogen Receptors alpha (α) and beta (β) are present. This cellular tissue includes: ovaries, corpus luteum, uterus, breast, adrenal glands, liver, skin, muscle, bone and fatty tissue. The capability for androgen conversion into estrogen in granulosa cells within the ovaries is very important for reproductive health.
Herbs that have properties as aromatase inhibitors include: ginkgo biloba, mint, garlic, clover, bay leaf, pueraria and legumes. Phytohormones among many plants that have aromatase inhibitor properties include: naringenin, hersperetin, eriodictyol, biochanin A, stilbene and lignans. Many of these herbs downregulate aromatase capacity, when used in large amounts.
Sensitization of aromatase capacity
Mint is an aromtase inhibitor that reduces estrogen conversion capacity when used in large amounts. This is expected for other aromatase inhibitors. In small amounts, however, mint upregulates aromatase capacity. It is possible that small amounts of other aromatase inhibitors upregulate aromatase enzymes.
Because aromatase capacity of granulosa cells is important for health, mint, clover and pueraria should be used in minimal amounts.
DHT is a strong hormone that desensitizes steroid receptors. It is known that DHT downregulates androgen receptors, so it is likely it also downregulates estrogen receptors as well. Surprisingly, androgens, including DHT, resensitize aromatase enzymes in mammals (unlike in birds and in fish).
Several phytohormones inhibit DHT, but herbs that contain these phytohormones are not always good for female health. Herbs that are diuertic, that raise LH, that desensitize estrogen receptors, that desensitize aromatase or have a reputation for causing hot flashes are not suitable for reducing potent effects of androgen symptoms.
5α-dihydrotestosterone (5α-DHT) neutralization
DHT cannot be converted into estrogens, because its molecular structure is saturated.
However, 5α-DHT can react with the phytohormone equol, canceling out the potent androgenic hormone, 5α-dihydrotestosterone. Equol, however, doesn't generally bind to 5β-dihydrotestosterone (5β-DHT). Equol, which comes in two forms r-equol and s-equol, is a metabolite of daidzein and genistein. Daidzein and genistein are found in legumes. The selective androgen modular (SAM) equol can also be found in cabbage. Corn is another source of either daidzein, genistein or equol. Unfortunately, equol reduces aromatase capacity when used in large amounts, and it has negligible effect when used in small amounts.
DHT can be converted into βdiol, an androgen with estrogenic properties, through neural cells. The conversion of DHT into βdiol is not considered aromatase.
- Modulation of Aromatase by Phytoestrogens. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4699002/.
- Equol an isoflavonoid: potential for improved prostate health, in vitro and in vivo evidence. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3032666/.
- Equol inhibits growth, induces atresia, and inhibits steroidogenesis of mouse antral follicles in vitro. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4779678/.
- Androgens upregulate cyp19a1b (aromatase B) gene expression in the brain of zebrafish (Danio rerio) through estrogen receptors. https://www.ncbi.nlm.nih.gov/pubmed/19129512.