Polycystic Ovarian Syndrome and Soy

Soybeans contain isoflavones, chemicals that are similar to estrogen. These are widely thought to be the active ingredients in soy, although there is substantial evidence that other constituents may be equally or more important.

The quality of the soy being consumed is extremely important. Some claim that as much as 90% of the soy being grown in the United States is "genetically modified organisms" or GMOs. This means the seeds of these crops have been modified in a laboratory in such a way to alter their natural state. The implications of such GMOs is not yet known, but it is speculated that having been modified, consuming too much of these products can have a negative effect on one's health.

Soy has been said to possibly help with hormone regulation for those with PCOS.

Read more details about Soy.

Safety Issues

Studies in animals have found soy essentially nontoxic. ¹ And it is reassuring to note that researchers found no evidence of ill effects when they gave healthy postmenopausal women 900 mg of soy isoflavones a day for 84 consecutive days. ² However, soy or its isoflavones could conceivably have some potentially harmful effects in certain specific situations.

Soy appears to have numerous potential effects involving the thyroid gland. When given to individuals with impaired thyroid function , soy products have been observed to reduce absorption of thyroid medication. ^{3 4 5 6 7 8 9 10 11 12 13 14 15 16} In addition, some evidence hints that soy isoflavones may directly inhibit the function of the thyroid gland, although this inhibition may only be significant in individuals who are deficient in iodine. ¹⁷ However, to make matters even more confusing, studies of healthy humans and animals given soy isoflavones or other soy products have generally found that soy either had no effect on thyroid hormone levels or actually increased levels. ¹⁸ The bottom line: In view of soy’s complex effects regarding the thyroid, individuals with impaired thyroid function should not take large amounts of soy products except under the supervision of a physician.

One study found that soy products may decrease testosterone levels in men. ¹⁹ This could conceivably cause problems for men with infertility or erectile dysfunction .

Soy may reduce the absorption of the nutrients zinc, iron, and calcium. ^{20 21 22 23} To avoid absorption problems, you should probably take these minerals at least 2 hours apart from eating soy.

Other concerns relate to the estrogenic properties of soy isoflavones. For example, while soy is thought to reduce the risk of developing breast cancer, it is possible that soy might not be safe for women who have already had breast cancer. In addition, there are concerns that intensive use of soy products by pregnant women could exert a hormonal effect that impacts unborn fetuses. Finally, fears have been expressed by some experts that soy might interfere with the action of oral contraceptives . However, one study of 36 women found reassuring results. ²⁴ For more information on these and other safety issues regarding the isoflavones in soy, see the full Isoflavones article.

One observational study raised concerns that soy might impair mental function. ²⁵ However, observational studies are highly unreliable by nature, and experts do not consider this a serious issue. ²⁶ Additionally, a number of studies looking at cognitive improvement have found that soy or soy isoflavones either have no effect on mental function, or perhaps minimally improve it. ²⁷

Interactions You Should Know About

If you are taking:

• Zinc , iron , or calcium supplements: It may be best to eat soy at a different time of day to avoid absorption problems.

• Thyroid hormone : You should consult your physician before increasing your intake of soy products.