Soy

Soy causes miscarriage and infertility in mice

Female mice were treated with genistein, the primary phytoestrogen in soy, on Neonatal Days 1-5 at doses of 0.5, 5, or 50 mg/kg per day. Soy-treated mice had prolonged menstrual cycles with a dose- and age-related increase in severity of abnormal cycles. Females treated with 0.5 mg/kg genistein or 5 mg/kg genistein bred at 2, 4, and 6 mo showed statistically significant decreases in the number of live pups over time with increasing dose; at 6 mo, 60% of the females in the 0.5 mg/kg genistein group and 40% in the 5 mg/kg group delivered live pups compared with 100% of controls. Mice treated with 50 mg/kg did not deliver live pups. At 2 mo, >60% of the mice treated with 50 mg/kg genistein were fertile as determined by uterine implantation sites, but pregnancy was not maintained; miscarriage was characterized by fewer, smaller implantation sites and increased reabsorptions. Mice treated with lower doses of soy had increased numbers of corpora lutea compared with controls, while mice treated with the highest dose had decreased numbers; however, superovulation with eCG/hCG yielded similar numbers of oocytes as controls. Serum levels of progesterone, estrogen, and testosterone were similar between soy treated and control mice when measured before puberty and during pregnancy. In summary, neonatal treatment with soy caused abnormal menstrual cycles, altered ovarian function, early reproductive senescence, and subfertility/infertility at environmentally relevant doses.

http://www.ncbi.nlm.nih.gov/pubmed/15930323

Soy increased follicular phase by 1.46 days and menstrual cycle by 3.52 days

Sixty-eight consecutively recruited, premenopausal, omnivorous women of all races and ethnicities between the ages of 25 years and 55 years were admitted to the study and randomized to an experimental group supplemented with soy protein (40 mg genistein per day) or to a control group that consumed a placebo for a 12-week period. Those women in the experimental group who were consuming soy had their mean menstrual cycle length increased by 3.52 days compared with a mean decrease of 0.06 days for women in the placebo group from baseline to the third menstrual cycle (from 26.27 to 29.81 days vs. 27.82 to 27.55 days). In addition, women who were taking soy had their mean follicular phase increase by 1.46 days compared with a mean increase of 0.14 days for women who were taking the placebo (from 11.79 to 13.62 days vs. 13.19 to 13.07 days).

http://findarticles.com/p/articles/mi_m0FDN/is_3_7/ai_88823876/

Soy decreases LH, FSH, estrogen, free T3 and DHEAS

Isoflavones were consumed in soy protein powders and provided relative to body weight (control diet, 10; low isoflavone diet, 64; high isoflavone diet, 128 mg/day) for three menstrual cycles plus 9 days in a randomized cross-over design. During the last 6 weeks of each diet period, plasma was collected every other day for analysis of estrogens, progesterone, LH, and FSH. Diet effects were assessed during each of four distinctly defined menstrual cycle phases. Plasma from the early follicular phase was analyzed for androgens, cortisol, thyroid hormones, insulin, prolactin, and sex hormone-binding globulin. The low isoflavone diet decreased LH and FSH levels during the periovulatory phase. The high isoflavone diet decreased free T3 and dehydroepiandrosterone sulfate levels during the early follicular phase and estrone levels during the midfollicular phase. No other significant changes were observed in hormone concentrations or in the length of the menstrual cycle, follicular phase, or luteal phase.

http://jcem.endojournals.org/cgi/content/full/84/1/192

Soy decreases luteal estrogen levels by 9.3%

Soy intervention was associated with a statistically significant reduction in serum luteal estrogen level (-9.3%, P < 0.05), but there were no significant changes in follicular phase estrogen, follicular or luteal phase progesterone, sex hormone-binding globulin or menstrual cycle length.

http://www.ncbi.nlm.nih.gov/pmc/articles/PMC2363237/pdf/82-6691218a.pdf

Soy decreases estrogen by 23% and 27% and lengthened menstrual cycle by 2 days

Premenopausal Japanese women were randomly assigned to receive either a soymilk-supplemented diet or a normal (control) diet. The women in the soymilk-supplemented group were asked to consume about 400 mL of soymilk (containing about 109 mg of isoflavones) daily during a study period that involved three consecutive menstrual cycles. At the end of the study period, estrone and estradiol levels were decreased by 23% and 27%, respectively, in the soymilk-supplemented group and were increased by 0.6% and 4%, respectively, in the control group. The changes for each hormone between the two groups were not statistically significantly different. In the soymilk-supplemented group, menstrual cycle length was increased by nearly 2 days, and, in the control group, it was decreased by approximately 1 day, a difference that was not statistically significant.

http://jnci.oxfordjournals.org/content/90/23/1830.full.pdf

Soy increased the length of follicular phase and lowered LH and FSH

Soy protein (60 g containing 45 mg isoflavones) given daily for 1 mo significantly increased follicular phase length and/or delayed menstruation. Midcycle surges of luteinizing hormone and follicle-stimulating hormone were significantly suppressed during dietary intervention with soy protein. Plasma estradiol concentrations increased in the follicular phase and cholesterol concentrations decreased 9.6%.

http://www.ajcn.org/cgi/reprint/60/3/333.pdf