A new perspective on the quercetin paradox in male reproductive dysfunction

Dietary bioflavonoids represent a large class of polyphenolic compounds found in most plants. A significant number of flavonoids are reported to have beneficial health effects. Quercetin is one such flavonoid which has been reported to possess strong antioxidant properties. However, as far as male reproduction and fertility are concerned, controversial reports exist in the literature highlighting the antioxidant as well as a prooxidant character of quercetin, leaving much to the researcher's speculation. The present review therefore, aimed at addressing this paradoxical behavior of quercetin by taking into account the in vitro and in vivo studies conducted till date regarding its role in the maintenance of male reproductive potential. From the detailed survey of the published data, it appears that the conflicting biological effects of quercetin might relate to its dose and the redox state of the cell. Thus, the cellular toxicity of quercetin metabolites might overshadow the beneficial effects of its supplementation in subjects having reproductive dysfunction coupled with elevated oxidative stress leading to the paradoxical behavior of the flavonoid.