Your Fertility Friend – Soy

If you’ve been eating soyfoods like soymilk and tofu for a while now, or even if you’ve recently introduced soy to your diet, you may be wondering about the impact of it on your fertility. You may have even seen or heard studies claiming negatives impacts. Well, we’ve done some research and we found that consuming whole soyfoods doesn’t negatively affect your health!

In a 1993 study, women living in a controlled environment for two months had an average increase of two and a half days in the length of time between menstrual periods when they ate soy, which attests to the powerful effect phytoestrogens can have on a woman’s body.

This type of evidence has led a few scientists to wonder if eating large amounts of soy can lower fertility, but most authorities, including Mark Messina, Ph.D., author of The Simple Soybean and Your Health, points out that Chinese and Japanese women have no trouble with fertility levels, despite daily high soy intake. Kenneth Setchell, Ph.D., professor of Pediatrics at Children’s Hospital and Medical Center in Cincinnati says that, though soy lengthens the cycle, it does not prevent ovulation and there is still a normal menstrual cycle.

There is also some evidence that eating soy can enhance fertility in men. The isoflavone genistein may be used to treat male sterility because it affects blood levels of LH [luteinizing hormone], needed for normal sperm production. Soybeans are also high in zinc, a mineral used by the body in the formation of many hormones and which also functions as an antioxidant. Zinc deficiency has been shown to affect reproduction in animals.

A more recent review reported in The American Journal of Clinical Nutrition states that reproductive and developmental toxicity studies did not find significant variations in fertility from soy phytoestrogens consumption in healthy couples, indicating that normal intake of soy is basically harmless to your fertility and hence your chances of becoming pregnant or maintaining a pregnancy.

Most recently, a study presented October 19, 2005, at the annual meeting of the American Society for Reproductive Medicine, “Eating a diet rich in soy or taking soy supplements probably won’t harm a woman’s fertility.” Researchers found female monkeys who took soy supplements containing twice the level of the plant estrogens eaten by Asian women for a year did not experience any negative changes in their menstrual cycle or ovarian function that might affect fertility. The study was by Kaplan, J. “High Isoflavone Soy Protein Does not Alter Menstrual Cyclicity or Ovarian Function in Fully Mature, Premenopausal Monkeys.”

“Our results suggest that a high-soy diet probably won’t compromise fertility in women. But our results confirmed earlier findings that fertility may be affected by stress levels,” lead researcher Jay Kaplan, of Wake Forest Baptist, said in a prepared statement.