The soy component genistein has been found to disrupt the normal development of ovaries in female mice, although a similar effect in humans has yet to be proven.The new study, conducted by researchers at the National Institute of Environmental Health Sciences (NIEHS) in the US, together with the Syracuse University, adds to a mounting body of evidence linking genstein to reproductive problems. Female mice that were injected with genistein during the first five days of their life were found to have reduced fertility, or to be totally infertile, according to the study, which was published in the January issue of Biology of Reproduction. The latest findings follow previous research by the NIEHS that showed that mice given genistein immediately after birth had irregular menstrual cycles, problems with ovulation, and problems with fertility as they reached adulthood. The scientists now say that these reproductive problems are partly a result of alterations to the ovaries during early development caused by the soy component. The newly born mice that received high doses of genistein were found to have a high percentage of oocytes- or egg cells- remaining in clusters, which means these were less likely to be fertilized. However, the study also points out that although newborn mice treated with genistein have multi-oocyte follicles (MOFs), and egg cells derived from these have a reduced fertilization rate, there is no proof that this is the case in humans. In other words, it is still unclear if genistein has an effect on human egg cells.
