Is There a Link Between Soy and Fertility?

Fertility and soy, a perfect match?

It is not easy to decipher the possible link between fertility and soy foods and whether there is a positive, negative, or no influence on the consumption of dietary soy and an individual's fertility health.

There have been small studies and case reports to support all three.

What We Do Know

Let's establish what we do know: Soy is an isoflavone. This is a plant component that has antioxidant and estrogenic activity. Since isoflavones have a similar structure to estrogen, they get the name “phyto” or plant estrogen.

The estrogenic activity can be agonist (exciting) or antagonist (blocking). This important dual function is what is typically absent from the discussion around soy as an estrogen substitute. 

This estrogen-blocking activity can be so significant that we would recommend soy products even to women who have had breast cancer, to lower their chance of the cancer returning.

Soy and Female Fertility

Most of the negative information about soy is due to presumed estrogen action and does not take into account the fact that soy products act on different estrogen receptors that decrease the harmful effects of estrogen.

The literature is highly supportive of soy food consumption and its association with a lower risk of breast, prostate, ovarian, uterine cancers, and decreased incidence of osteoporosis and bone fractures.

Soy consumption has been shown to increase positive outcomes in women going through fertility treatments.

Soy and Sperm

One study did show a lower sperm concentration in men eating more soy products, but the same study showed higher semen volume with a total sperm concentration unchanged.

To date, research shows that soy consumption has not been harmful to men’s overall sperm quality.

The Bottom Line

Soy products have high antioxidant activity, which is beneficial for overall health. More research is needed, and the last words on soy’s effects have not been spoken.

For the time being the overall benefits appear to outweigh any risks and enjoying soy food, especially in an unprocessed state should be encouraged in moderation.

Author

Dr. Richard Schmidt Richard J. Schmidt, MD, FACOG, is the medical director and laboratory program director at NOVA IVF. He is passionate about delivering compassionate, patient-centered fertility care to his patients, resulting in thousands of babies and recognition as one of the nation's Top Doctors.