Soy Infant Formulas Get Clean Bill of Reproductive Health
The researchers also looked for differences in cancer rates between the two formula groups, but none were found. A possible explanation is that the study group is still relatively young (aged 20-34) and, therefore, participants are less likely to have developed cancer.
Janice M. Bahr, PhD, a scientist who studies the effect of plant-based estrogen-like compounds (called phytoestrogens) in animals tells WebMD that concerns about the effects of phytoestrogens first arose when Australian ranchers noticed that female sheep that grazed on a type of clover found to be high in isoflavones became infertile, and that male sheep had difficulty urinating due to enlarged prostate glands, also from exposure to estrogen-like chemicals.
People would have to eat diets that are much higher in soy than normal to get high levels of exposure to large isoflavones, says Bahr, professor of animal sciences, physiology, and molecular and integrative physiology at the University of Illinois at Champaign-Urbana.
"But there are now all these health food stores that are carrying isoflavone capsules. No one really knows how much is in there, because unless you know the purification process, you really don't know how much you're taking. But the levels can be quite high, so that people who are taking the isoflavone extract in a capsule or as a food additive could be ingesting very high levels of phytoestrogens," Bahr cautions. "It's interesting, because none of these [supplements] have been evaluated by the FDA, so any companies who are producing and marketing them do not have to respond to any rigorous regulation."