Summary of points:
Estrogen is a hormone that serves as a chemical messenger in the body. For women, it helps control their menstrual cycle, breast growth, maintain healthy bones and a healthy heart. From puberty to menopause, the ovaries produce estrogen. In addition to estrogen the ovaries also produce progesterone, that works in counterbalance with estrogen during the menstrual cycle.
The balance between estrogen and progesterone can be upset by many factors and this imbalance becomes more pronounced during the five-year or so period of bodily transition before full menopause, called “peri-menopause.” During this period, estrogen and progesterone levels in the body can fluctuate unpredictably (in both excess "dominance" or in deficiency) until ultimately declining. These fluctuations cause a variety of uncomfortable symptoms, such as hot flashes, night sweats, vaginal dryness and vaginal thinness. Women may also notice decreased libido, a decrease in arousal and orgasmic response, fatigue, weight gain, joint pains, mood swings, sleep disturbance, and hair loss. It also marks the beginning stages of an increased risk of heart disease and osteoporosis. Once menopause sets in, the ovaries no longer make estrogen or progesterone. Instead, body fat becomes the primary source for estrogen and the adrenal glands the source of low levels of progesterone, however this can be blocked in adrenal exhaustion.
Despite the increased sales in phytoestrogen products in recent years, especially those containing soya phytoestrogens, many have reported that the positive effects are too slow or only very mild. This is because some phytoestrogens work better than others. Recent scientific studies have shown that the most potent and safe phytoestrogen found in nature comes from a tropical rain forest plant in Southeast Asia called Pueraria mirifica. This herb has been used for centuries by both women and men in Thailand. The key ingredient in Pueraria mirifica is a unique phytoestrogen named miroestrol. Miroestrol is similar to the safest human estrogen estriol. Miroestrol is 3000 times stronger than the estrogenic activity exhibited by soy isoflavones (genistein). In addition to miroestrol, Pueraria mirifica contains substantial amounts of other phytoestrogens including daidzein, genistein, puerarin, and mirificin. When miroestrol enters an estrogen receptor it modulates the effect on the receptor, either increasing its effects when the estrogenic activity is low or diluting its effects if the receptor estrogenic activity is high.
Because of this, Pueraria mirifica is considered an estrogen balancer in both estrogen deficiency and estrogen dominance. What is important to understand is that the phytoestrogens such as miroestrol help to balance or modulate the estrogen receptor. If the estrogen levels are too high (estrogen dominance) then the phytoestrogen can protect the receptor from overstimulation and if the estrogen levels are too low then the phytoestrogen will exert estrogenic activity without actually increasing the amount of estrogen in your body.