Could the isoflavones in soy infant formula cause long-term reproductive problems or infertility for human infants?
Dr. Kenneth Setchell from the Children’s Hospital Medical Center, Cincinnati, USA, first reported that soy infant formulas contained high levels of naturally occurring isoflavones1, confirming observations made 13 years ago2. Despite these high levels, there have never been any case reports in the medical and scientific literature that isoflavones cause later infertility in human infants. Recent questions regarding the levels of isoflavones in soy-based infant formulas have been raised. The negative effects of extremely high doses of isoflavones on the fertility and development in animals such as sheep3 and cheetah4 have been known for many years and extensively investigated. In these cases, blood levels were 100-500 times higher than what we see in infants fed soy infant formula. However, there are large species differences in how phytoestrogens are handled, and in their effects. Animals such as monkeys5, rats6, mares and cattle7 do not experience reproductive problems when fed a diet
