Study #1: Quercetin’s Fertility Effects On Female Mice
In a 2014 paper called ‘Effects of dietary quercetin on female fertility in mice: implication of transglutaminase 2’ by Beazley & Nurminskaya (full report) researchers found a jaw-dropping 81% reduction in viable offsprings birthed from middle aged mice when the mice were dosed with quercetin at a daily dose of just 5 mg/kg body weight.
There was also a less pronounced decrease of 14% in the number of offspring of the female mice in their prime reproductive months (2-6 months).
The researchers tracked two metrics for the two treatment groups for both of the age brackets: litters per dam & pups per litter. Here is that data for the two age brackets:
This is extremely troubling when looking at the prevalence of high dose quercetin supplementing.
Also concerning is the huge 104% increase in the ovary weight in the querectin treated animals:
“Our study shows for the first time that dietary quercetin can cause reduced reproductive potential in female mice”
“In conclusion, our data support the proposition that some activities of quercetin and its metabolites may overshadow the beneficial effects of its supplementation in females of reproductive age, calling for further analysis of the clinical data to relate our findings in mice to humans”
Study #2: Quercetin’s Fertility Effects On Male Mice
In another study called ‘Quercetin impairs the reproductive potential of male mice’ by Ranawat et al (full report):
“Quercetin increased the generation of reactive oxygen species and lipid peroxidation in the testis with concomitant decrease in sperm count and motility in a dose-dependent manner.”
“Germ cell kinetic study revealed significant loss of various germ cell populations with increasing dose of quercetin.”
Look at the massive 99.9% reduction in the total motile count (a key indicator of male fertility) at 20 mg/kg quercetin:
“The present in vivo study is an extension of our previous in vitro work wherein it was found that quercetin impaired human normal sperm motility and viability (Khanduja et al., 2001). Concomitant with the results obtained in our previous study, the present study also showed a decrease in sperm motility and concentration and altered testicular histomorphology with increasing dose of quercetin.”
“We found that quercetin affects the motility of spermatozoa and that all spermatozoa were rendered immotile at higher concentrations.”
“The previous in vitro studies reported that quercetin had inhibitory effects on membrane-bound Ca2+ -ATPase, a key enzyme involved in the regulation of sperm motility (Breitbart et al., 1985; Khanduja et al., 2001). The decreased activity of this enzyme results in Ca2+ accumulation in the cells, which in turn causes blockade of the motility apparatus and a concomitant fall in motility (Breitbart et al., 1985).”
“The histomorphology demonstrated alterations in testicular morphology such as epithelial vacuolisation and atrophy in the groups exposed to quercetin. Also, a dose-dependent increase in the extent of damage caused by the bioflavonoid was observed in our mouse model.”
“It was observed that the lumen diameter increased and germ cell height decreased with increasing doses, suggestive of thinning of the germinal epithelium and disintegration of germ cells caused by the bioflavonoid.”
“The quantitative analysis of various germ cell populations revealed a decrease in the proportion of germ cells with increasing doses of quercetin, thereby highlighting extensive damage caused by the compound.”
“The testicular morphology in the high-dose group was indicative of regressive changes in the germinal epithelium and is caused by destruction and loss of the inter-cellular bridges that are essential for the process of spermatogenesis, spermiogenesis and synchronisation of germ cell maturation (Holstein & Eckmann, 1986).”
“Quercetin impairs spermatogenesis not only by acting directly on the germ cells as a pro-oxidant, but also might be directly affecting the Sertoli cell structure and functions.”
