Effect of a phytoestrogen food supplement on reproductive health in normal males

Abstract

Animal studies and human intervention trials have demonstrated the cancer chemopreventive properties of plant phytoestrogens, and phytoestrogen supplements are now widely available 'over-the-counter'. However, consumption of phytoestrogen-rich diets can cause impaired fertility and reproductive tract disorders in some animals and the apparent decline in human sperm quality over recent decades may be related to increased exposure to environmental endocrine disruptors. The present study determines the effects of a short-term phytoestrogen supplement on semen quality and serum sex steroid and gonadotrophin levels in human males. Healthy volunteers took a supplement containing 40 mg of isoflavones daily for 2 months and donated blood and semen samples monthly for 2 months before and 4 months after supplementation. Semen samples were analysed for ejaculate volume, sperm concentration, total sperm count, motility and morphology. Blood samples were analysed for sex hormone and gonadotrophin levels and phytoestrogen concentrations, and testicular volume was measured using an orchidometer. The phytoestrogen supplement increased plasma genistein and daidzein concentrations to approx. 1 microM and 0.5 microM respectively; yet, there was no observable effect on endocrine measurements, testicular volume or semen parameters over the study period. This is the first study to examine the effects of a phytoestrogen supplement on reproductive health in males. We conclude that the phytoestrogen dose consumed had no effect on semen quality.

Occupational and Lifestyle Exposures on Male Infertility: A Mini Review

“…Evidence coming from animal models [102] and human studies has shown that increasing levels of phytoestrogens intake can disrupt both the normal development [103] and the function of the male reproductive system [80]. However, we have found only one report in which adult males were given phytoestrogen supplements (isoflavone) and only for a short period of time (20 days) without finding an effect on semen quality [104].…”

Xenopus laevis is a potential alternative model animal species to study reproductive toxicity of phytoestrogens

“…Simultaneously, some authors reported that there are no significant effects of phytoestrogens in rodents (Roberts et al, 2000;Mitchell et al, 2001;Lamartiniere et al, 2002). One of the explanations for these inconsistent results is that commercial rodent diets all contain high and variable levels of abundant phytoestrogens, which could affect results of studies on reproductive toxicity of test phytoestrogens (Odum et al, 2001;Stroheker et al, 2003;Naciff et al, 2004;Thigpen et al, 2004).…”

Soy, phytoestrogens and their impact on reproductive health

“…A report from Mitchell et al limited to only 14 individuals, showed no influence on semen quality or sexual hormones in young males orally consuming 40 mg/day of soy-isoflavones (i.e. genistein, daidzein, glycitein), for 2 months (Mitchell et al, 2001). To add more confusion, an in vitro study showed that low concentrations of genistein (1, 10 and 100 nM) caused an accelerated capacitation and acrosome loss in human spermatozoa (Fraser et al, 2006).…”