Some felid diets contain isoflavones but the metabolic capacity of cats towards isoflavones is relatively unknown, despite the understanding that isoflavones have divergent biological potential according to their metabolite end-products. The objective of this study was to determine the plasma metabolites detectable in domestic cats after exposure to two different dietary forms of isoflavones.
Serial blood samples were collected after isoflavone exposure to identify the plasma metabolites of each cat. Genistein was detected in its unconjugated form or as a monosulfate. Daidzein was detected as both a mono- and di-sulfate, as well as in its unconjugated form. Other daidzein metabolites detected included equol mono- and di-sulfate, dihydrodaidzein, and O-desmethylangolensin. No β-glucuronide metabolites of either isoflavone were detected. Equol was produced in markedly fewer cats after ingestion of a soy extract tablet as a single oral bolus compared to cats consuming an isoflavone-containing diet. The detectable metabolites of the isoflavones, genistein and daidzein in domestic cat plasma after dietary ingestion may have been described in the present study for the first time.
The metabolic capacity for isoflavones by domestic cats appears to be efficient, with only minimal proportions of the ingested amount detected in their unconjugated forms. This has implications for the potential of isoflavones to exert physiological activity in the domestic cat when consumed at concentrations representative of dietary intake.
Source: K.M. Whitehouse-Tedd et al., 2013. Isoflavone metabolism in domestic fcats (Felis catus): comparison of plasma metabolites detected after ingestion of two different dietary forms of genistein daidzein. J Anim Sci online January 2013. doi: 10.2527/jas.2011-4812