Soy isoflavones have been purported to help induce ovulation in women experiencing non-ovulatory or irregular ovulation cycles. While there is insufficient evidence to prove or disprove their usefulness toward that end, some research indicates that high doses of isoflavone-rich soy protein can interfere with the natural mid-cycle surges of luteinizing hormone and follicle-stimulating hormone, thus potentially interfering with fertility.
Understanding Soy Isoflavones
Isoflavones are a type of phytoestrogens -- plant-derived micronutrients that exhibit estrogenic activity on the human body, notes an article published on the Linus Pauling Institute website. While isoflavones are found in legumes, grains and vegetables, the richest sources of isoflavones in the human diet are soybeans and other foods that contain soy products. Phytogestrogens have the ability to bind to estrogen receptors throughout the body, such as in the heart, brain and liver, the report explains. When they bind to the estrogen receptors, they mimic the effect of estrogen in some tissues while blocking the effects in others. Research to determine the extent to which soy isoflavones mimic or inhibit the effects of estrogen in different tissues remains inconclusive.
Fertility and Soy Isoflavones
Clomiphene citrate -- a fertility drug -- acts as an estrogen blocker in the hypothalamus. It can be used to manipulate a menstrual cycle by triggering ovulation in anovulatory (non-ovulating) cycles or by regulating irregular ovulation, according to an article on the website of the American Society for Reproductive Medicine. Some speculate that soy isoflavones can be used in the same way. Because soy isoflavones can both mimic and block estrogen, however, some may mimic estrogen -- convincing the body that there is an abundant supply and decreasing rather than increasing production. Soy isoflavones may also decrease the production of follicle-stimulating hormone and luteinizing hormone, both of which are involved in ovulation, according to a meta-analysis in the journal "Human Reproduction Update."
Soy products and soy isoflavones appear to be safe when consumed as part of a regular diet. Speak with your health care provider, however, before using soy isoflavone supplements or large amounts of dietary soy isoflavones to aid in fertility. For women who ovulate regularly, soy isoflavones will not improve the likelihood of conceiving and may interfere with fertility.
Supplementing With Soy Isoflavones
Licensed acupuncturist Jill Blakeway says that if you use a soy isoflavone supplement to increase the likelihood of ovulation, you should start with 80 to 200 mg per day. Blakeway told the BabyCenter that such a supplement should be taken only for either of two five-day stretches during your menstrual cycle: days 3 through 7 or days 5 through 9. The dosage, she said, should be maintained at the same level for each of the five days.